International travel and health Module 2: Environmental health risks
International travel and health Module 2: Environmental health risks International travel and health. Module 2. Environmental health risks (International travel and health) ISBN 978-92-4-009360-7 (electronic version) ISBN 978-92-4-009361-4 (print version) © World Health Organization 2024 Some rights reserved. This work is available under the Creative Commons Attribution-NonCommercial-ShareAlike 3.0 IGO licence (CC BY-NC-SA 3.0 IGO; https://creativecommons.org/licenses/by-nc-sa/3.0/igo). Under the terms of this licence, you may copy, redistribute and adapt the work for non-commercial purposes, provided the work is appropriately cited, as indicated below. In any use of this work, there should be no suggestion that WHO endorses any specific organization, products or services. The use of the WHO logo is not permitted. If you adapt the work, then you must license your work under the same or equivalent Creative Commons licence. 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The mention of specific companies or of certain manufacturers’ products does not imply that they are endorsed or recommended by WHO in preference to others of a similar nature that are not mentioned. Errors and omissions excepted, the names of proprietary products are distinguished by initial capital letters. All reasonable precautions have been taken by WHO to verify the information contained in this publication. However, the published material is being distributed without warranty of any kind, either expressed or implied. The responsibility for the interpretation and use of the material lies with the reader. In no event shall WHO be liable for damages arising from its use. Cover photo: Credit: WHO/Petra Hongell Boy jumping off a pontoon into the sea. iii Contents Foreword iv Acknowledgements v Contributors v Declaration of interest vii Module 2: Environmental health risks 1 1. Heat 1 1.1 Overview 1 1.2 Health effects 1 1.3 Protective measures 2 2. Ultraviolet radiation 5 2.1 Overview 5 2.2 Health effects 5 2.3 Protective measures 6 3. Air pollution 8 3.1 Exposure to high levels of air pollution 9 3.2 Precautions for travellers in highly polluted areas 10 4. Safe food, safe water and diarrhoeal diseases 14 4.1 Water and health 14 4.2 Foodborne illness 14 4.3 Diarrhoeal diseases 14 5. Recreational waters 18 6. Zoonoses 20 6.1 Prevention 20 7. Vector-borne diseases 22 7.1 Vectors 22 7.2 Vector-borne diseases 22 7.3 Vector-borne diseases, according to their vector 22 7.4 Protection against vectors 24 iv Foreword Depending on the health profile of the traveller, the type of travel to be undertaken, and the place of transit and destination, travellers may face various health risks during travel. The International travel and health is an update of International travel and health (2012) and serves as an entry point for other World Health Organization (WHO) publications that provide further information. Its primary target audience is travel health practitioners and travel health professionals who provide health advice to travellers on appropriate precautions to be taken to minimize any travel-related health risks in unfamiliar environments, before, during and after travel. The guidance may also be useful to health authorities who intend to support travel health professionals in their jurisdiction or develop health advice for their population. It may also be of interest to travellers who wish to obtain such information for themselves as well as those working in the travel industry, such as agents and organizers, airlines and shipping companies. Module 2: Travellers often experience abrupt and dramatic changes in environmental conditions, which may have detrimental effects on their health and well-being. Travel may involve major changes in altitude, temperature and humidity, and exposure to microbes, animals and insects. The negative impact of sudden changes in the environment can be minimized by taking simple precautions. vAcknowledgements The World Health Organization would like to express its gratitude for the collaborative efforts of all those involved in making this process efficient, trustworthy and transparent. Contributors This module was updated by the following contributors: WHO headquarters staff Dr Bernadette Abela, Neglected Tropical Diseases/Public Health, Vector Control and Environment Dr Stéphane De La Rocque, Human Animal Interface for IHR, Health Security Preparedness Dr Pierre Formenty, Health Emergency Interventions/High Impact Epidemics Dr Qudsia Huda, Disaster Risk Management and Resilience, Health Security Preparedness Dr Anais Legand, Health Emergency Interventions/High Impact Epidemics Dr David Meddings, Social Determinants of Health/Healthier Populations Dr Kate Medlicott, Water, Sanitation, Hygiene and Health Environment, Climate Change and Health Dr Simone Moraes Raszl, Multisectoral Action in Food Systems, Nutrition and Food Safety Dr Peter Olumese, Diagnostics, Medicine and Resistance, Global Malaria Programme Dr Samantha Pegoraro, Environment, Climate Change and Health Dr Ingrid Rabe, Emerging Diseases and Zoonoses, Epidemic and Pandemic Preparedness and Prevention Dr Ankur Rakesh, Disaster Risk Management and Resilience, Health Security and Preparedness Dr Diana Rojas Alvarez, Emerging diseases and Zoonoses/Epidemic and Pandemic Preparedness and Prevention Dr Raman Velayudhan, Neglected Tropical Diseases/Public Health, Vector Control and Environment Dr Emilie Van Deventer, Environment, Climate Change and Health Dr David Williams, Access to Medicines and Health Products, Vaccines and Immunization Devices Assessment vi WHO Regional Office for Europe Dr Pierpaolo Mudu, Environment, Climate Change and Health/Air Quality and Health/Living and Working Environments External contributors Contributing members of the International Travel and Health (ITH) Editorial Peer Review Group (EPRG) Dr Bhawana Amatya Consultant General Practitioner Travel Medicine Specialist Site Director, Kathmandu GeoSentinel Site CIWEC Hospital and Travel Medicine Centre Kathmandu Nepal Dr Andrea Boggild Medical Director Division of Infectious Diseases Department of Medicine Toronto General Hospital and University of Toronto Canada Dr Sarah Borwein General Practitioner, Travel Medicine Practitioner Former GeoSentinel Site Director Hong Kong Beacon Medical Centre China, Hong Kong SAR Ms Lindsay Lee Wheelchair-using frequent traveller, Data Analyst United States of America Dr Kokou Nouwame Alinon Principal Technical Officer Division of Surveillance and Disease Intelligence Africa Centres for Disease Control and Prevention Addis Ababa Ethiopia Dr Dipti Patel Director National Travel Health Network and Centre United Kingdom of Great Britain and Northern Ireland vii Professor Patricia Schlagenhauf Epidemiology, Biostatistics and Prevention Institute Department of Public and Global Health WHO Collaborating Centre for Travellers’ Health University of Zurich Switzerland Declaration of interest All external contributors of the International Travel and Health Editorial Peer Review Group (EPRG) completed a WHO declaration of interests form in accordance with WHO policy for experts. The declarations of interest and the results of a web-based search for each member were reviewed by the WHO staff. No conflict of interest was declared by any of the EPRG members. Credit: WHO/Ala Kheir A child washes their hands during a cholera awareness raising activity for internally displaced people (IDPs) at Barakat School in Wad Madani on 22 October 2023. The school is now a host centre for 85 internally displaced families from Khartoum. 1. Heat 1 Module 2: Environmental health risks Travellers often experience abrupt and dramatic changes in environmental conditions, which may have detrimental effects on their health and well-being. Travel may involve major changes in altitude, temperature and humidity, and exposure to microbes, animals and insects. The negative impact of sudden changes in the environment can be minimized by taking simple precautions. 1. Heat 1.1 Overview A heatwave is a marked unusual period of hot weather over a region persisting for at least two consecutive days during the hot period of the year based on local climatological conditions, with thermal conditions recorded above given thresholds (World Meteorological Office, 2020). As a consequence of climate change, the frequency and intensity of heatwaves is expected to continue rising in almost all regions of the world. Therefore, travellers should consider that dangerous high temperatures can be experienced in almost all regions of the world during the summer months. The health impact of a heatwave depends on the intensity and duration of the high temperatures, the acclimatization and adaptation of the population, and their preparedness to face it. However, various measures could help people and communities to better prepare to face high-temperature events and ameliorate negative effects on health and well-being. 1.2 Health effects 1.2.1 Direct effects of heatwave exposure Exposure to heat can cause severe symptoms, such as heat exhaustion, heat stress and heat stroke. These can present as faintness, dry and warm skin due to the inability of the body to adapt to high temperatures, swelling in the lower limbs, heat rash on the neck, cramps, headache, irritability, lethargy and weakness. In extreme cases, heat can also cause severe dehydration, acute cerebrovascular accidents and contributes to thrombogenesis (blood clots). Ultimately, extreme high temperatures can lead to death. 1.2.2 Exacerbation of pre-existing health conditions due to heatwaves People with chronic conditions who take daily medications are at a greater risk of complications and death during a heatwave, especially older people and children. Prolonged exposure to periods of high temperature exacerbates other comorbidities like respiratory, cardiovascular, metabolic and renal diseases (Cheng et al, 2019; Moon, 2021; Lee et al, 2019). Furthermore, short periods of exposure to heatwaves can lead to public health emergencies and can impact on the lives, livelihoods and health of populations especially the most vulnerable (Boyle et al. 2010; Margolis , 2021). 2International travel and health | Module 2: Environmental health risks Multiple vulnerabilities increase the risk of health impacts: The less abled, pregnant, or already infirm The poor, displaced, and homeless Children & the elderly Athletes Outdoor & manual workers Source: Heat and health [key facts]. Geneva: World Health Organization; 2018 (https://www.who.int/news-room/fact- sheets/detail/climate-change-heat-and-health). 1.2.3 Indirect effects of heatwaves Heatwaves exacerbate and magnify the effects, intensity and severity of various other hazards such as wildfires, droughts, cyclones, urban heat islands and poor air quality. People travelling to places with a high risk of heatwaves should be aware of the related climate events that can take place during or after the high-heat days or season. Direct Impacts Impact on health services Increased risk of accidents Increased transmission of Potential disruption of infrastructure: Accelerated death from: Heat illness Hospitalization Health Impacts of Exposure to Extreme heat • Increased ambulance call-outs and slower response times • Drowning • Food and waterborne diseases • Power • Respiratory disease • Respiratory disease • Diabetes mellitus • Renal disease • Stroke • Mental health conditions • Cardiovascular disease • Other chronic disease (mental health, renal disease) • Heat cramps • Dehydration • Heat stroke • Water • Transport • Productivity • Marine algal blooms • Work-related accidents • Injuries and poisonings • Increased number of hospital admissions • Response times • Storage of medicines Indirect Impacts Source: Heat and health [key facts]. Geneva: World Health Organization; 2018 (https://www.who.int/news-room/ fact-sheets/detail/climate-change-heat-and-health). 1.3 Protective measures Reactions to heat depend on each person’s ability to adapt, and serious effects can appear suddenly. Therefore, it is important to pay attention to the alerts and recommendations of local authorities. In addition, it is crucial to be aware of the local conditions through liaising with the local community and knowing about the heat-resilient infrastructure for seeking shelter. Travel health facilities should keep records of countries and regions with a high risk for seasonal heatwave events to enable them to advise travellers accordingly. Although avoiding these areas is not always possible, it is important to reduce exposure to heat at the hottest 1. Heat 3 time of the day and during the days on which extreme temperatures have been predicted. Other basic recommendations for travellers are to map out in advance possible climate shelters they can seek, to stay hydrated, to wear sunscreen with a high SPF and to wear climate-appropriate garments, including hats and sunglasses. As mentioned above, it is also important for travel health practitioners and travellers to acknowledge the probability of related climate events, such as cyclones, droughts and wildfires and to prepare for them. Simple actions that the public could take to minimize the adverse health impacts of heatwaves are depicted in the infographics. Throughout a HEATWAVE, keep yourself cool and hydreated Drink water regularly. Avoid alcohol and too much caffeine and sugar Eat small meals and eat more often Wear light, loose-fitting clothes Wear a hat or cap and sunglasses. Take cool showers or baths If you feel unwell during a HEATWAVE Get help if you feel dizzy, weak, anxious or have intense thirst and headache Move to a cool place as soon as possible Drink some water to rehydrate Keep medicines below 25°C or in the refigerator Infographic: Throughout a heatwave, keep yourself cool and hydrated Infographic: If you feel unwell during a heatwave Throughout a HEATWAVE, try to keep out of heat Stay in the shade Avoid going outside during the hottest time of the day Avoid strenuous physical activities if you can Do not leave children or animals in parked vehicles During a HEATWAVE help others who suffer from the heat Take a first-aid course to learn how to treat heat emergencies and other emergencies Check on family, friends, and neighbours who spend much of their time alone. Elderly or sick people living alone should be visited at least daily. Infographic: Throughout a heatwave, try to keep out of heat Infographic: During a heatwave, help others who suffer from the heat 4International travel and health | Module 2: Environmental health risks References • Boyle C, Mudd G, Mihelcic JR, Anastas P, Collins T et al. (2010). Delivering sustainable infrastructure that supports the urban built environment. Environ Sci Technol. 44,13:4836–40 (https://pubs.acs.org/doi/10.1021/es903749d). • Cheng J, Xu Z, Bambrick H, Prescott V, Wang N, Zhang Y, et al. (2019). Cardiorespiratory effects of heatwaves: A systematic review and meta-analysis of global epidemiological evidence. Environ Res. 177:108610. doi: 10.1016/j.envres.2019.108610. Epub 2019 Jul 26. PMID: 31376629. • Lee WS, Kim WS, Lim YH, Hong YC. (2019). High temperatures and kidney disease morbidity: A systematic review and meta-analysis. J Prev Med Public Health. 52:1–13. doi: 10.3961/jpmph.18.149. Epub 2018 Nov 20. PMID: 30742756; PMCID: PMC6378387. • Margolis HG (2021). Heat waves and rising temperatures: Human health impacts and the determinants of vulnerability. In: Pinkerton KE, Rom WN (eds) Climate change and global public health. Cham: Humana (https://doi.org/10.1007/978-3-030-54746-2_7). • Moon J. (2021). The effect of the heatwave on the morbidity and mortality of diabetes patients; a meta-analysis for the era of the climate crisis. Environ Res. 195:110762. doi: 10.1016/j.envres.2021.110762. Epub 2021 Jan 27. PMID: 33515577. • WMO (2023). Guidelines on the definition and characterization of extreme weather and climate events Geneva: World Meteorological Office; 2023 (https://library.wmo.int/ records/item/58396-guidelines-on-the-definition-and-characterization-of-extreme- weather-and-climate-events) Further information • Heat and health (2018). [fact sheet]. Geneva: World Health Organization (https://www. who.int/news-room/fact-sheets/detail/climate-change-heat-and-health). • World Health Organization. Regional Office for Europe (2011). Public health advice on preventing health effects of heat: new and updated information for different audiences. Copenhagen: World Health Organization. Regional Office for Europe (https://apps.who.int/iris/handle/10665/341580). • Heatwaves [health topic]. Geneva: World Health Organization (https://www.who.int/ health-topics/heatwaves#tab=tab_2). Credit: WHO/Adele Sarkozi Heatwaves across Europe are affecting the health and livelihoods of millions of people. In 2022 in the WHO European Region, extreme heat claimed more than 60 000 lives, and by 2050 this could rise to 120 000 heat-related deaths every year. Climate change is increasing the risk of heatwaves, and extreme heat in the summer months is becoming the norm, not the exception. 2. Ultraviolet radiation 5 2. Ultraviolet radiation 2.1 Overview Ultraviolet (UV) radiation covers the wavelength range of 100–400 nm, which is a higher frequency and lower wavelength than visible light. UV radiation comes naturally from the sun, but it can also be created by artificial sources used in industry, commerce and recreation. The UV wavelengths are divided into three bands: • UVA (315–400 nm) • UVB (280–315 nm) • UVC (100–280 nm) As sunlight passes through the atmosphere, all UVC and approximately 90% of UVB radiation is absorbed by ozone, water vapour, oxygen and carbon dioxide. UVA radiation is less affected by the atmosphere. Therefore, the UV radiation reaching the Earth’s surface is largely composed of UVA with a small UVB component. The amount of UV radiation from the sun that hits the Earth’s surface depends on several factors, including: • Sun elevation: the higher the sun is in the sky, the higher the UVR level; UVR levels vary with time of day and time of year. • Latitude: the closer to the equator, the higher the UVR levels. • Altitude: UVR levels increase with altitude as the air is thinner at high altitudes and less UVR is absorbed. • Cloud cover: UVR levels are highest under cloudless skies but can be high even with cloud cover. • Ozone: ozone absorbs part of the UVR from the sun. Less ozone means more UVR reaches the Earth’s surface. • Reflection: reflective surfaces, such as water, sand and fresh snow, increase the UVR level. • Climate change, including through variations in ozone and cloud cover, is expected to impact UVR levels at the Earth’s surface. Reductions in the ozone layer due to human-created pollution increase the amount of UVA and UVB that reaches the Earth’s surface. This can impact human health, animals, marine organisms and plant life. In humans, increased UV exposure can cause skin cancers, cataracts and immune system damage. 2.2 Health effects Small amounts of UVR are beneficial to health and play an essential role in the production of vitamin D. However, excessive exposure to UVR is associated with negative health consequences as UVR is carcinogenic to humans. 6International travel and health | Module 2: Environmental health risks 2.2.1 Effects on the skin Acute effects of UVR include DNA damage, sunburn, phototoxic and photoallergic reactions, and suppression of the immune system. Immunosuppression can be considered as a risk factor for cancer and can cause reactivation of viruses (e.g. cold sores on the lip). Chronic effects on skin and lips from UVR exposure include: • cutaneous melanoma: a life-threatening malignant skin cancer; • squamous cell carcinoma (SCC): a malignant cancer, which generally spreads less than melanoma and is less likely to cause death; • basal cell carcinoma (BCC): a slow-growing skin cancer appearing predominantly in older people; and • premature skin ageing: a loss of skin elasticity at a young age with decreased wound healing. Excessive exposure to UVR caused around 1.2 million new cases of non-melanoma skin cancers (SCC and BCC) and 325 000 melanomas of the skin, and 64 000 premature deaths from non-melanoma and 57 000 melanomas of the skin in 2020. 2.2.2 Effects on the eyes Acute effects of UVR include photokeratitis and photoconjunctivitis (inflammation of the cornea and conjunctiva, respectively). These effects are reversible, easily prevented by protective eyewear and are not usually associated with any long-term damage but are painful and might require therapeutic intervention. Chronic effects of UVR include: • cataract (an eye disease where the lens becomes increasingly opaque, resulting in impaired vision and eventual blindness); • pterygium (growth of fleshy tissue which can cover part of the cornea); and • cancer in and around the eye (BCC, SCC and melanoma). UV exposure may also be involved in the development of age-related macular degeneration. Worldwide, it is estimated that 15 million people are blind due to cataracts; of these, some 10% may be due to exposure to UVR. 2.2.3 Vitamin D production UVR in small amounts is essential to good health as it leads to the production of vitamin D in the body. Vitamin D strengthens the bone and musculoskeletal system. People who have very low sun exposure – such as those in institutional care or who are housebound, people with deeply pigmented skin living in high latitudes or those who, for religious or cultural reasons cover their entire body surface when they are outdoors – should consider oral vitamin D supplementation. 2.3 Protective measures Skin cancer is highly preventable. WHO recommends the following measures to protect against excessive exposure to UVR. • Limit time in the midday sun. • Seek shade. 2. Ultraviolet radiation 7 • Wear protective clothing. • Wear a broad-brimmed hat to protect the eyes, face, ears and neck. • Wear wraparound-style sunglasses that provide 99 to 100% protection against UVA and UVB. • Use broad-spectrum sunscreen, which protects against both UVA and UVB radiation, on areas of skin that cannot be covered by clothes. Sun protection is best achieved by seeking shade and wearing clothes rather than applying sunscreens. Sunscreens should not be used as a way of extending the time spent in the sun. • Avoid use of artificial tanning devices. Sunbed use increases the risk of developing skin cancers. Artificial tanning should never be considered as an option to achieve sufficient vitamin D status. Several countries have implemented legislation to ban or restrict the use of sunbeds. Encouraging children to take the simple precautions above will prevent both short-term and long-term damage while still allowing them to enjoy the time they spend outdoors. Simple steps to lower your risk of developing skin and eye diseases: Be aware of the UV index, whereever you are. Download the SunSmart Global UV App Seek shade Wear sun-protective clothing Put on a broad-brimmed hat Slide on sunglasses Apply sunscreen Ultraviolet radiation from the sum causes over 1.5 million skin cancers every year References • Ultraviolet radiation – Overview. [health topic]. Geneva: World Health Organization (https://www.who.int/health-topics/ultraviolet-radiation). • Ultraviolet radiation (2022). [fact sheet] Geneva: World Health Organization (https://www. who.int/news-room/fact-sheets/detail/ultraviolet-radiation). 8International travel and health | Module 2: Environmental health risks 3. Air pollution The vast majority of the population of the planet is exposed to unsafe levels of polluted air, which represents a significant global threat to human and public health. Each year, the combined effects of ambient air pollution and household air pollution are responsible for approximately 7 million premature deaths, mostly in low- and middle-income countries, where hardly any of the cities meet WHO air quality guidelines (World Health Organization, 2021). OUR VITAL ORGANS 36% 34% 27%AIR POLLUTION STROKEHEART DISEASECOPDLUNG CANCER PNEUMONIA AIR POLLUTION AFFECTS OF DEATHS FROM LUNG CANCER OF DEATHS FROM STROKE OF DEATHS FROM HEART DISEASE Air pollution is associated with increased mortality and morbidity, mostly from noncommunicable diseases such as ischaemic heart disease, stroke, chronic obstructive pulmonary disease and lung cancer, but also from acute lower respiratory tract infections such as pneumonia, which mainly affects children living in disadvantaged settings. Furthermore, a growing and consistent body of evidence shows that additional effects of air pollution on health include preterm and low-birthweight, exacerbation and onset of asthma, as well as cognitive and neurological impairment. The impact of air pollution is higher on vulnerable individuals with a low socioeconomic status who are subjected to greater exposure levels and on susceptible individuals with pre-existing health conditions or in specific life stages, for example, older people, newborns, children and pregnant women. Additionally, people who are active or work outdoors or who live near busy roads or industrial areas are at risk of high levels of exposure. Poor air quality affects us all and long-term consequences are the main effects to be considered. However short-term acute effects are more evident as they are responsible for the increase in hospital emergency admissions in a short span of time (for example, during days of unbearable levels of air pollution in cities). This often represents a source of public alarm. Air pollution is a mixture of solid and liquid substances commonly referred to as “particulate matter” (PM) as well as gas. Fine particulate matter (PM2.5) is the most widely used indicator for estimating the health impacts of air pollution. Common sources of air pollution include anthropogenic sources such as heat and power generation, traffic, industry, agriculture, building sector, waste burning as well as non-anthropogenic sources such as desert dust. Another important source is wildfires. These different sources are associated with specific air pollutants. For example, heat and power generation relying on fossil fuels emit sulfur dioxide, nitrogen dioxides and PM. Motor vehicles and traffic-related sources release significant amounts of nitrogen oxides and carbon monoxide. Waste burning emits PM and carcinogens such as dioxins, furans and black carbon. Building sector activities can contribute to increases 3. Air pollution 9 in the levels of PM. Sources emitting nitrogen dioxide are also responsible for the generation of substances that can potentiate global warming substances (for example, ozone and black carbon, which is a component of PM). The tourism industry has a significant impact on both global warming and air pollution emissions, often putting pressure on local environments and communities. WHO recommends specific air quality levels to be respected so as to protect the health of populations. The most recent recommendations were formulated for the following pollutants: PM2.5, PM10, ozone, nitrogen dioxide, sulfur dioxide and carbon monoxide (World Health Organization, 2021). 3.1 Exposure to high levels of air pollution Although long-term effects of air pollution generate the bulk of the burden of disease for public health, it is important for travellers to consider exposure that may occur over a short period in places with high levels of air pollution. The scientific literature suggests that short-term daily exposure to PM2.5, ozone, nitrogen dioxide and sulfur dioxide is associated with several adverse health outcomes and increased emergency hospital admissions due to cardiovascular and respiratory events. For example, ozone, even at low levels, causes inflammation, lung function decline and respiratory symptoms leading to increased medication use by patients with chronic illness. It also leads to hospital admissions and emergency department visits related to exacerbations of asthma and/or chronic obstructive can aggravate respiratory diseases, particularly asthma Well planned public transport, along with safe walking and cycling can: • improve air quality • mitigate climate change • improve physical activity Nitrogen dioxide pollution from traffic, power plants, industry or agriculture 10 International travel and health | Module 2: Environmental health risks pulmonary disease. Beyond its acute toxicity at high concentrations, short-term exposure to carbon monoxide is associated with ischaemic heart disease and other cardiovascular events. Increased mortality from respiratory diseases and asthma attacks requiring emergency care have been related to short-term exposure to nitrogen dioxide and sulfur dioxide. It is also important to be aware that air pollution potentiates the allergenicity of pollen, potentially leading to more severe respiratory symptoms. Acute and chronic diseases exacerbated by air pollution exposure are the same as those known to be responsible for more severe cases of COVID-19. 3.2 Precautions for travellers in highly polluted areas Travellers should acquire information on air quality to be better prepared for their destination, particularly if they have respiratory, cardiovascular or metabolic conditions, and especially when visiting cities with consistently poor air quality. In particular, data on current levels (or on annual mean concentrations, key sources and seasonal variations) of PM2.5 and other pollutants such as nitrogen dioxide, carbon monoxide, ozone and sulfur dioxide should be consulted. Air quality indexes are produced by the governmental authorities in many countries to report daily air quality and alert the public when air pollution is high (World Health Organization, 2020; Cromar & Lazrak, 2023). Individuals with heart and lung conditions are at increased risk of becoming ill and needing treatment. However, only a minority of those who suffer from these conditions are likely to be affected and it is not possible to predict in advance who will be affected. SOURCES OF AIR POLLUTION ARE A GLOBAL CHALLENGE WE MUST TACKLE TOGETHER INDUSTRY & ENERGY SUPPLY DUST AGRICULTURAL PRACTICES HOUSEHOLD ENERGY CLEAN AIR FOR HEALTH WHO Air Quality Guidelines set goals to protect millions of lives from air pollution TRANSPORT WASTE MANAGEMENT 3. Air pollution 11 The health effects of air pollution on travellers is an important matter that needs to be addressed. Although a limited number of studies have been published so far, the results already give cause for concern (Vilcassim, 2019; Vilcassim, Callahan & Zierold, 2021). International travellers should be aware that air pollution affects their health, particularly the most vulnerable groups such as older people, children, pregnant women and people living with chronic conditions. Before travelling Travellers should gather information on the levels of air pollution in the places they plan to visit. They should also be aware that there may be seasonal variations due to human activities (for example, burning of crop residues or increased use of biomass for heating) or related to natural sources (dust storms or wildfires). Travellers with a chronic health condition or older travellers should visit their health practitioner before starting their trip. Adults and children with asthma may notice that they need to increase their use of inhaled reliever medication on days when levels of air pollution are higher than average (Met Office). Travellers with asthma or chronic obstructive pulmonary disease should consult their doctor about travelling with an inhaler, antibiotics or oral steroids. Pregnant women and travellers with newborns or young children should avoid destinations with high levels of air pollution as far as possible (IAMAT, 2020). It is important to keep in mind that there are significant deficits in the coverage of travel health topics online, although COPD websites have the best quality (Rofaiel, Hession & Flaherty, 2021). Authorities responsible for providing travel advice should be encouraged to include information on air quality and its potential health implications as part of their guidelines for users. At the destination • Reduce your exposure: in all cases, common-sense precautions should be adopted for avoiding high levels of exposure to air pollution. • Check the availability of an air quality index and related health recommendations. Be aware that some countries have early warning systems for informing the public about how they can reduce sources of outdoor and indoor air pollution. • For some individuals, the following are important: » Patients who take medication should follow their physician’s recommendations. » Individuals with asthma or other respiratory conditions should be advised not to undertake strenuous exercise when ambient air pollution levels are high (WHO, 2020). “The limited evidence on the impact of air pollution on the short-term beneficial effects of physical activity indicate that these effects may be diminished, although not completely eliminated, in populations with diseases such as cardiovascular and respiratory conditions and also in healthy populations. At similar levels of air pollution, people with pre- existing conditions benefit less from physical activity than healthy individuals. The evidence also suggests that, in the presence of air pollution, patients on medication benefit more from physical activity than people without medication” (WHO, 2020). » Due to a lack of evidence, no definitive recommendations for children, pregnant women, people with illnesses and populations from low- and middle-income countries can be made on physical exertion in destinations where air pollution is above the levels stipulated in the WHO air quality guidelines (WHO, 2020). 12 International travel and health | Module 2: Environmental health risks » Evidence from healthy adult populations in high-income countries supports continued promotion of regular physical activity, even if the air quality does not reach the levels recommended by WHO, as the health benefits of physical activity are maintained. • Although staying indoors and/or reducing physical activity are classic public health precautions for reducing exposure when air pollution is elevated, these may not be possible or even advisable, for everyone. Changing the location, timing and type of outdoor activity can, however, modify and therefore reduce exposure to pollution, as the levels of air pollutants vary both spatially and temporally. The recommendation should include consideration of ozone levels and temperature, especially in warmer climates. • In countries exposed to sand and desert dust storms, which produce high levels of PM, it is important to check short-term air pollution action plans alerting the population to stay indoors and heed advice on taking personal measures to minimize exposure and prevent subsequent short-term health effects. • Wearing a face mask is advisable during acute episodes of air pollution such as during a wildfire, but masks do not fully filter out all pollutants, and in most cases can only reduce exposure to large pollution particles. Face masks need to be worn correctly if they are to reduce exposure. Most face masks do not fit children’s faces. • Behavioural changes made to avoid exposure to air pollution should be properly thought through as they might have unintended consequences such as reducing the benefits of outdoor physical activity and social interaction. • Travellers should be aware of the need reduce their impact on local air pollution, reduce their environmental footprint and support local and sustainable practices (United Nations World Tourism Organization (UNWTO), 2022). References • IAMAT [International Association for Medical Assistance to Travellers] (2020). Air pollution and travel: How to stay safe and reduce your impact [blog] (https://www.iamat.org/blog/ air-pollution-and-travel-how-to-stay-safe-and-reduce-your-impact/). • Met Office. Information on how to use the daily air quality index including additional advice for susceptible individuals [webpage] (https://www.metoffice.gov.uk/weather/ guides/air-quality). • Rofaiel DP, Hession P, Flaherty GT. (2021). Analysis of web-based travel health advice provided to international travellers with chronic medical and psychiatric illnesses. Int J Med Informat. 154:104566 (doi: 10.1016/j.ijmedinf.2021.104566). • UNWTO [United Nations World Tourism Organization]. (2022). Sustainable development. Madrid: United Nations World Tourism Organization (https://www.unwto.org/ sustainable-development). • Vilcassim MR, Thurston GD, Chen LC, Lim CC, Saunders E, Yao Y et al. (2019). Exposure to air pollution is associated with adverse cardiopulmonary health effects in international travellers. J Travel Med. 26:taz032 (https://doi.org/10.1093/jtm/taz032). • Vilcassim MJR, Callahan AE, Zierold KM. (2021). Travelling to polluted cities: a systematic review on the harm of air pollution on international travellers’ health. J Travel Med. 28:taab055 (https://doi.org/10.1093/jtm/taab055). • World Health Organization. (2020). Personal interventions and risk communication on air pollution. Geneva: World Health Organization (https://apps.who.int/iris/ handle/10665/333781). 3. Air pollution 13 • World Health Organization. (2021). WHO global air quality guidelines. Particulate matter (PM2.5 and PM10), ozone, nitrogen dioxide, sulfur dioxide and carbon monoxide. Geneva: World Health Organization (https://apps.who.int/iris/handle/10665/345329). Further information WHO publications: • Ambient (outdoor) air pollution [fact sheet] Geneva: World Health Organization (https:// www.who.int/news-room/fact-sheets/detail/ambient-(outdoor)-air-quality-and-health). • Air pollution: The invisible health threat [online]. Geneva: World Health Organization (https://www.who.int/news-room/feature-stories/detail/air-pollution--the-invisible- health-threat). • Wildfires [online]. Geneva: World Health Organization (https://www.who.int/health- topics/wildfires#tab=tab_1). Others: • Cromar K, Lazrak N. (2023). World Health Organization Regional Office for Europe. Risk communication of ambient air pollution in the WHO European Region: review of air quality indexes and lessons learned. Copenhagen: World Health Organization. Regional Office for Europe (https://apps.who.int/iris/handle/10665/365787). Credit: WHO/Kiana Hayeri On 25 November 2022, a boy plays with a kite on a hillside in Kabul. Air pollution in the city below is clearly visible. 14 International travel and health | Module 2: Environmental health risks 4. Safe food, safe water and diarrhoeal diseases 4.1 Water and health Contaminated water and poor sanitation are linked to transmission of diseases such as cholera, salmonellosis and other diseases that cause diarrhoea and dysentery, hepatitis A, typhoid and polio. Absent, inadequate or inappropriately managed water and sanitation services expose individuals to preventable health risks (WHO, 2023). 4.2 Foodborne illness Unsafe food containing harmful bacteria, viruses, parasites or chemical substances causes more than 200 diseases, with consequences ranging from diarrhoea to cancers. It also creates a vicious cycle of disease and malnutrition, particularly affecting infants, young children, older people and the sick. Foodborne diseases are usually infectious or toxic in nature and caused by bacteria, viruses, parasites or chemical substances entering the body through contaminated food. Some examples of the organisms and the affected foods are listed below. Bacteria: • Salmonella, eggs, poultry and other products of animal origin • Campylobacter: raw milk, raw or undercooked poultry and drinking-water • Enterohaemorrhagic Escherichia coli: unpasteurized milk, undercooked meat and contaminated fresh fruits and vegetables • Listeria: unpasteurized dairy products and various ready-to-eat foods – can grow at refrigeration temperatures • Vibrio cholerae: raw vegetables, and raw or undercooked seafood. Viruses: • Hepatitis A: raw or undercooked seafood or contaminated raw produce. 4.3 Diarrhoeal diseases Diarrhoea is defined as the passage of three or more loose or liquid stools per day (or more frequent passage than is normal for the individual). Frequent passing of formed stools is not diarrhoea, nor is the passing of loose, “pasty” stools by breastfed babies. When diarrhoea contains blood or mucus, it is called dysentery. 4. Safe food, safe water and diarrhoeal diseases 15 Diarrhoea or dysentery are usually a symptom of an infection in the intestinal tract, which can be caused by a variety of bacterial, viral and parasitic organisms. Infection is spread through contaminated food or drinking-water, or from person to person as a result of poor hygiene. Key measures to prevent diarrhoea and dysentery include: • access to safe drinking-water; • use of improved sanitation; • hand washing with soap; • exclusive breastfeeding for the first six months of life; • good personal and food hygiene during food-handling and preparation; • health education about how infections spread; and • being up to date with necessary vaccinations. A WHO guide on safe food for travellers Afghanistan Albania Algeria Andorra Angola Antigua and Barbuda Argentina Armenia Australia Austria Azerbaijan Bahamas Bahrain Bangladesh Barbados Belarus Belgium Belize Benin Bhutan Bolivia Bosnia and Herzegovina Botswana Brazil Brunei Darussalam Bulgaria Burkina Faso Burundi Cambodia Cameroon Canada Cape Verde Central African Republic Chad Chile China Colombia Comoros Congo Cook Islands Costa Rica Côte d’Ivoire Croatia Cuba Cyprus Czech Republic Democratic People’s Republic of Korea Democratic Republic of the Congo Denmark Djibouti Dominica Dominican Republic Ecuador Egypt El Salvador Equatorial Guinea Eritrea Estonia Ethiopia Fiji Finland France Gabon Gambia Georgia Germany Ghana Greece Grenada Guatemala Guinea Guinea-Bissau Guyana Haiti Honduras Hungary Iceland India Indonesia Iran Iraq Ireland Italy Jamaica Japan Jordan Kazakhstan Kenya Kiribati Kuwait Kyrgyzstan Lao People’s Democratic Republic Lebanon Lesotho Liberia Libyan Arab Jamahiriya Lithuania Luxembourg Madagascar Malawi Malaysia Maldives Mali Malta Marshall Mauritania Mauritius Mexico Micronesia Monaco Mongolia Montenegro Morocco Mozambique Myanmar Namibia Nauru Nepal Netherlands New Zealand Nicaragua Niger Nigeria Niue Norway Oman Pakistan Palau Panama Papua New Guinea Paraguay Peru Philippines Poland Portugal Qatar Republic of Korea Republic of Moldova Romania Russian Federation Rwanda Saint Kitts and Nevis Saint Lucia Saint Vincent and the Grenadines Samoa SanMarino Sao Tome and Principe Saudi Arabia Senegal Serbia Seychelles Sierra Leone Singapore Slovakia Slovenia Solomon Islands Somalia South Africa Spain Sri Lanka Sudan Suriname Swaziland Sweden Switzerland Syrian Arab Republic Tajikistan Thailand The former Yugoslav Republic of Macedonia Timor-Leste Togo Tonga Trinidad and Tobago Tunisia Turkey Turkmenistan Tuvalu Uganda Ukraine United Arab Emirates United Kingdom of Great Britain and Northern Ireland United Republic of Tanzania United States of America Uruguay Uzbekistan Vanuatu Venezuela Viet Nam Yemen Zambia Zimbabwe Afghanistan Albania Algeria Andorra Angola Antigua and Barbuda Argentina Armenia Australia Austria Azerbaijan Bahamas Bahrain Bangladesh Barbados Belarus Belgium Belize Benin Bhutan Bolivia Bosnia and Herzegovina Botswana Brazil Brunei Darussalam Bulgaria Burkina Faso Burundi Cambodia Cameroon Canada Cape Verde Central African Republic Chad Chile China Colombia Comoros Congo Cook Islands Costa © W or ld H ea lth O rg an isa tio n, 2 00 7 Afghanistan Albania Algeria Andorra Angola Antigua and Barbuda Argentina Armenia Australia Austria Azerbaijan Bahamas Bahrain Bangladesh Barbados Belarus Belgium Belize Benin Bhutan Bolivia Bosnia and Herzegovina Botswana Brazil Brunei Darussa- lam Bulgaria Burkina Faso Burundi Cambodia Cameroon Canada Cape Verde Central African Republic Chad Chile China Colombia Comoros Congo Cook Islands Costa Rica Côte d’Ivoire Croatia Cuba Cyprus Czech Republic Democratic People’s Republic of Korea Demo- cratic Republic of the Congo Denmark Djibouti Dominica Dominican Republic Ecuador Egypt El Salvador Equatorial Guinea Eritrea Estonia Ethiopia Fiji Finland France Gabon Gambia Georgia Germany Ghana Greece Grenada Guatemala Guinea Guinea-Bissau Guya- na Haiti Honduras Hungary Iceland India Indonesia Iran Iraq Ireland Italy Jamaica Japan Jordan Kazakhstan Kenya Kiribati Kuwait Kyrgyzstan Lao People’s Democratic Republic Lebanon Lesotho Liberia Libyan Arab Jamahiriya Lithuania Luxembourg Madagascar Malawi Malaysia Maldives Mali Malta Marshall Mauritania Mauritius Mexico Micronesia Monaco Mongolia Montenegro Morocco Mozambique Myanmar Namibia Nauru Nepal Netherlands New Zealand Nicaragua Niger Nigeria Niue Norway Oman Pakistan Palau Panama Papua New Guinea Paraguay Peru Philippines Poland Portugal Qatar Republic of Korea Republic of Moldova Romania Russian Federation Rwanda Saint Kitts and Nevis Saint Lucia Saint Vincent and the Grenadines Samoa SanMarino Sao Tome and Principe Saudi Arabia Senegal Ser- bia Seychelles Sierra Leone Singapore Slovakia Slovenia Solomon Islands Somalia South Africa Spain Sri Lanka Sudan Suriname Swaziland Sweden Switzerland Syrian Arab Republic Tajikistan Thailand The former Yugoslav Republic of Macedonia Timor-Leste Togo Tonga Trini- dad and Tobago Tunisia Turkey Turkmenistan Tuvalu Uganda Ukraine United Arab Emirates United Kingdom of Great Britain and Northern Ireland United Republic of Tanzania United States of America Uruguay Uzbekistan Vanuatu Venezuela Viet Nam Yemen Zambia Zimbabwe What to do if you get diarrhoea ? Most diarrhoeal attacks are self-limited and clear up in a few days. Diarrhoea may be accompanied by nausea, vomiting and/ or fever. The important thing is to avoid becoming dehy- drated. Ensure that you always drink sufficient amounts of fluids, particularly when travelling in a hot climate. This is extremely important for children. If the child is restless or irri- table, or shows signs of strong thirst, or has sunken eyes, or dry skin with reduced elasticity, dehydration is already progressing and immediate medical attention should be sought. Should bowel movements be very frequent, very watery or contain blood, or last beyond 3 days you should seek medical help. Where there is no medical help available a complete 3-day course of ciprofloxacin* (500 mg twice a day for adults, 15mg/kg twice a day for children) can be taken. As soon as diarrhoea starts, drink more fluids, such as oral rehydration formula, boiled, treated or bottled water, weak tea, soups or other safe fluids. Avoid any drinks that tend to remove more water from the body, including coffee, overly sweetened drinks, some medicinal teas and alcohol. Age group Amount of fluids or ORS** to drink Children less than 2 years Up to ½ cup after each loose stool Children 2-10 years Up to 1 cup after each loose stool Older children and adults Unlimited amount Contrary to common belief, medicines which reduce bowel movements are not recommended. In children, these preparations should never be used as they may cause intestinal obstruction. * generic name - can be sold under other names ** If ORS are not available, mix 6 teaspoons of sugar plus one level teaspoon of salt in one litre of safe water (“taste of tears”) and drink as indicated in the table. Each day millions of people become ill and thousands die from a preventable foodborne disease The advice given in this leaflet is important for every traveller, and of particular importance for high-risk groups i.e. infants and young children, pregnant women, elderly and immunocompromised individuals, including those with HIV/AIDS; persons in these groups are particularly susceptible to foodborne diseases. Remember: Prevention is better than cure The WHO Five Keys to Safer Food global message is adapted in this guide to specifically address the health concerns associated with travel. The Five Keys to Safer Food global message is available at: www.who.int/foodsafety/consumer/5keys/en This document is published by the Department of Food Safety, Zoonoses and Foodborne Diseases E-mail: foodsafety@who.int Web site: www.who.int/foodsafety A GuidE on SAfE food foR TRAvEllERS How to avoid illnesses caused by unsafe food and drink and what to do if you get diarrhoea Gd_eng_new_list.indd 1 15.08.2007 13:56:02 ISB N: 97 89 24 15 97 66 1 Five keys to safer food This poster has been translated into nearly 90 languages and copies are available at: https:// www.who.int/teams/nutrition-and-food-safety/multisectoral-actions-in-food-systems/five- keys-to-safer-food-poster Reference • Drinking-water (2023). [fact sheet]. Geneva: World Health Organization (https://www.who. int/news-room/fact-sheets/detail/drinking-water). Further information • A guide on safe food for travellers: how to avoid illnesses caused by unsafe food and drink and what to do if you get diarrhoea (2007). Geneva: World Health Organization (https://www.who.int/publications/i/item/9789241597661 and https://apps.who.int/iris/ handle/10665/331265). 16 International travel and health | Module 2: Environmental health risks • Five keys to safer food. [poster]. Geneva: World Health Organization (https://cdn.who. int/media/docs/default-source/infographics-pdf/food-safety/five-keys-to-safer-food. pdf?sfvrsn=1cf1f432_2). Poster in 88 languages (https://www.who.int/teams/nutrition-and-food-safety/ multisectoral-actions-in-food-systems/five-keys-to-safer-food-poster). • Food safety (2022) [fact sheet]. Geneva: World Health Organization (https://www.who.int/ en/news-room/fact-sheets/detail/food-safety). 70°C 5 60 Danger zone! Five keys to safer foo d WHO/SDE/PHE/FOS/01.1 Distribution: General Original: English D es ig n : M ar ily n La n g fe ld . I llu st ra ti o n : J an et P et it p ie rr e Knowledge = PreventionFood SafetyWorld Health Organization Cook thoro ughly ✔ Cook food th oroughly, es pecially mea t, poultry, eg gs and seafo od ✔ Bring foods li ke soups and stews to boi ling to make sure that the y have reach ed 70°C. For m eat and pou ltry, make su re that juice s are clear, n ot pink. Ide ally, use a therm ometer ✔ Reheat cook ed food tho roughly Keep food a t safe temp eratures ✔ Do not leave cooked foo d at room te mperature fo r more than 2 hours ✔ Refrigerate p romptly all c ooked and p erishable foo d (preferably below 5°C) ✔ Keep cooked food piping hot (more t han 60°C) pr ior to serving ✔ Do not store food too lon g even in th e refrigerato r ✔ Do not thaw frozen food at room tem perature Use safe wa ter and raw materials ✔ Use safe wat er or treat it to make it sa fe ✔ Select fresh a nd wholeso me foods ✔ Choose food s processed for safety, su ch as pasteu rized milk ✔ Wash fruits a nd vegetabl es, especially if eaten raw ✔ Do not use fo od beyond i ts expiry dat e Keep clean ✔ Wash your h ands before handling fo od and often during food preparation ✔ Wash your h ands after go ing to the to ilet ✔ Wash and sa nitize all surf aces and eq uipment use d for food p reparation ✔ Protect kitch en areas and food from in sects, pests and other an imals Separate ra w and cook ed ✔ Separate raw meat, poult ry and seafo od from oth er foods ✔ Use separate equipment and utensil s such as kn ives and cut ting boards for handling raw foods ✔ Store food in containers t o avoid cont act between raw and pre pared foods Why? While most m icroorganisms do not cause disease, dang erous microor ganisms are widely found in soil, wate r, animals and people. T hese microor ganisms are carried on h ands, wiping cloths and utensils, espe cially cutting boards and the slightest contact can t ransfer them to food and ca use foodborn e diseases. Why? Microorgani sms can mu ltiply very quickly if fo od is stored at room temperature. By holding a t tempera- tures below 5°C or above 60°C, the growth of mi croorganisms is slowed down or stop ped. Some d angerous microorganism s still grow be low 5°C. Why? Proper cookin g kills almost a ll dangerous microorganism s. Studies have shown that cooking food t o a temperatu re of 70°C can help ensure i t is safe for c onsumption. Foods that r equire speci al attention include mince d meats, rolled roasts, large joints of meat and whole po ultry. Why? Raw materials , including wa ter and ice, may be conta minated with dangerous microorganis ms and chem icals. Toxic chemicals ma y be formed in damaged and mouldy f oods. Care in s election of raw material s and simple measures such as was hing and pe eling may reduce the ris k. Why? Raw food, esp ecially meat, poultry and seafood, and their juices, can contain dangerous m icroorganism s which may be transferred onto other fo ods during food preparat ion and storag e. °C °C 4. Safe food, safe water and diarrhoeal diseases 17 • Food safety (overview). Geneva: World Health Organization (https://www.who.int/health- topics/food-safety#tab=tab_1). • Promoting safe food-handling [webpage]. Geneva: World Health Organization (https:// www.who.int/activities/promoting-safe-food-handling). • Diarrhoeal disease (2017) [key facts]. Geneva: World Health Organization (https://www. who.int/news-room/fact-sheets/detail/diarrhoeal-disease). • Botulism (2023). [key facts]. Geneva: World Health Organization (https://www.who.int/ news-room/fact-sheets/detail/botulism). • Campylobacter (2020). [key facts]. Geneva: World Health Organization (https://www.who. int/news-room/fact-sheets/detail/campylobacter). • Listeriosis (2018). [key facts]. Geneva: World Health Organization (https://www.who.int/ news-room/fact-sheets/detail/listeriosis). • Salmonella (non-typhoidal) (2018). [key facts]. Geneva: World Health Organization (https:// www.who.int/news-room/fact-sheets/detail/salmonella-(non-typhoidal)). • Hepatitis A (2023). [key facts]. Geneva: World Health Organization (https://www.who.int/ news-room/fact-sheets/detail/hepatitis-a). • Cholera – What you need to know (2023). [infographic]. Geneva: World Health Organization (https://www.who.int/multi-media/details/cholera-dyk). • Cholera (2023). [fact sheet]. (https://www.who.int/news-room/fact-sheets/detail/ cholera). • E. coli (2018). [key facts]. Geneva: World Health Organization (https://www.who.int/news- room/fact-sheets/detail/e-coli). • WHO position papers on Typhoid. Geneva: World Health Organization (https://www.who. int/teams/immunization-vaccines-and-biologicals/policies/position-papers/typhoid). Credit: WHO/Sue Price Curry cooking at Ga Me Ga Hotel in Phuentsholing, Bhutan, on 13 August 2023. 18 International travel and health | Module 2: Environmental health risks 5. Recreational waters Use of coastal, estuarine and freshwater recreational environments has significant benefits for health and well-being, including rest, relaxation, exercise, cultural and religious practices and aesthetic pleasure, while also providing substantial local, regional and national economic benefits. Yet, human activity and climate change are impacting the quality and safety of our waters. Popular swimming locations may become contaminated by overflows of untreated sewage, runoff of animal excreta from nearby farms, or algal blooms triggered by high nutrient loads. Stagnant waters can be contaminated by bacteria such as Leptospira, by viruses (for example, hepatitis A and E) or by parasites such as schistosomes, which are the agent of schistosomiasis (bilharzia). Travellers become infected by ingesting water or when larvae penetrate the skin. Some sites may also be affected by chemical pollution from industrial activities or become polluted by beach users themselves through poor sanitation and littering. This contamination erodes the benefits to well-being and the economic potential of the site, as well as potentially causing illness for water users (WHO, 2021 Volume 1). Other potential health risks include drowning, in addition to exposure to sun, heat and cold. Risk factors that are associated with an increased risk of drowning include alcohol use, unfamiliarity with local water risks and features, and leaving infants unsupervised or alone with another child around water (WHO fact sheet: Drowning). References • WHO Guidelines on recreational water quality: Volume 1 coastal and fresh waters (2021). Geneva: World Health Organization (https://iris.who.int/handle/10665/342625). • Drowning [fact sheet]. Geneva: World Health Organization (https://www.who.int/news- room/fact-sheets/detail/drowning). Further information • WHO Guidelines on safe recreational water environments: Volume 2 Swimming pools and similar environments (2006). Geneva: World Health Organization (https://www.who.int/ publications/i/item/9241546808). • WHO (2022). Preventing drowning: Practical guidance for the provision of day-care, basic swimming and water safety skills, and safe rescue and resuscitation training. Geneva: World Health Organization (https://www.who.int/publications/i/item/9789240046726). • WHO (2017). Preventing drowning: an implementation guide. Geneva: World Health Organization (https://www.who.int/publications/i/item/9789241511933). • WHO (2021). Together, we can prevent drowning [video]. Geneva: World Health Organization (https://www.who.int/multi-media/details/liam-neeson-supports-world- drowning-prevention-day-commemoration). 5. Recreational waters 19 • WHO (2021). Global drowning prevention. Geneva: World Health Organization (https:// www.who.int/multi-media/details/global-drowning-prevention). Credit: WHO / Sören Talu Outdoor activities in beautiful Estonia. 20 International travel and health | Module 2: Environmental health risks 6. Zoonoses Zoonoses are diseases that are naturally transmitted from vertebrate animals to humans and vice versa. Zoonotic pathogens may be bacteria, viruses, parasites, fungi or even unconventional agents such as prions, and can be transmitted from animals to humans through direct contact, vectors, food, water or the environment. They represent a major public health problem around the world due to our close relationship with livestock, companion animals and wildlife. Zoonoses can also cause disruptions in the production and trade of animal products for food and other uses. More than six out of every 10 known infectious diseases in people can be spread from animals, and three out of every four new or emerging infectious diseases in people come from animals. Recent examples include severe acute respiratory syndrome (SARS), Middle East respiratory syndrome (MERS), coronavirus disease (COVID-19), avian flu, Ebola virus diseases, monkeypox (Mpox), Crimean-Congo haemorrhagic fever and salmonellosis, to name but a few. Endemic zoonoses such as rabies, taeniasis and echinococcosis are also threats to travellers in many parts of the world. 6.1 Prevention To prevent infection with zoonoses travellers should ensure that they know about: • access to safe food (such as meat, eggs, dairy products and even some vegetables); • access to safe drinking-water; • access to safe waste removal; • protections relating to surface water in the natural environment; • hand washing after contact with animals, and other behavioural adjustments; • the need to be careful in markets selling the meat or by-products of wild animals, which are particularly high risk due to the large number of new or undocumented pathogens known to exist in some wild animal populations; and • being up to date with necessary vaccinations. Further information • Zoonoses. (2015). [webpage]. Geneva: World Health Organization (https://www.who.int/ news-room/facts-in-pictures/detail/neglected-zoonotic-tropical-diseases). • Brucellosis. (2020). [key facts]. Geneva: World Health Organization (https://www.who.int/ news-room/fact-sheets/detail/brucellosis). • Leptospirosis: fact sheet. (2009). Geneva: World Health Organization (https://www.who. int/publications/i/item/B4221). • Waterborne zoonoses: identification, causes and control. (2004). Geneva: World Health Organization (https://www.who.int/publications/i/item/9241562730). 6. Zoonoses 21 • Ebola virus disease. [overview]. Geneva: World Health Organization (https://www.who. int/health-topics/ebola#tab=tab_1). • Lassa fever. [overview]. Geneva: World Health Organization (https://www.who.int/health- topics/lassa-fever). • Marburg virus disease. [overview]. Geneva: World Health Organization (https://www.who. int/health-topics/marburg-virus-disease). • Rift valley fever. [overview]. Geneva: World Health Organization (https://www.who.int/ health-topics/rift-valley-fever). • Guidelines for diagnosing and managing disseminated histoplasmosis among people living with HIV (2020). Geneva: World Health Organization (https://www.who.int/ publications/i/item/9789240006430). • EPI-WIN webinar: Managing plague in the field. 19 April 2023. Geneva: World Health Organization (https://www.who.int/news-room/events/detail/2023/04/19/default- calendar/epi-win-webinar-managing-plague-in-the-field-launch-of-the-who-plague- manual). • Update 86: Managing plague in the field. (2023). Technical document. Geneva: World Health Organization (https://www.who.int/publications/m/item/update-86-managing- plague-in-the-field). • Plague (2022). [key facts]. Geneva: World Health Organization (https://www.who.int/ news-room/fact-sheets/detail/plague). • Rabies. [overview]. Geneva: World Health Organization (https://www.who.int/health- topics/rabies#tab=tab_3). • WHO position papers on Rabies. Geneva: World Health Organization (https://www.who. int/teams/immunization-vaccines-and-biologicals/policies/position-papers/rabies). • Nipah virus infection. [overview]. Geneva: World Health Organization (https://www.who. int/health-topics/nipah-virus-infection#tab=tab_1). • Crimean-Congo haemorrhagic fever. (2022). [key facts]. Geneva: World Health Organization (https://www.who.int/news-room/fact-sheets/detail/crimean-congo- haemorrhagic-fever). Credit: WHO/Quinn Mattingly Vegetables are washed and prepared lunch at a rural home in northern Viet Nam. 22 International travel and health | Module 2: Environmental health risks 7. Vector-borne diseases 7.1 Vectors Vectors are living organisms that can transmit infectious pathogens between humans, or from animals to humans. Many of these vectors are bloodsucking arthropods (insects and ticks), which ingest disease-producing microorganisms during a blood meal from an infected host (human or animal) and later transmit it to a new host, after the pathogen has replicated. Often, once a vector becomes infectious, it is able to transmit the pathogen for the rest of its life during each subsequent bite/blood meal. 7.2 Vector-borne diseases Vector-borne diseases are human illnesses caused by parasites, viruses and bacteria that are transmitted by vectors. Every year there are more than 700 000 deaths from diseases such as malaria, dengue, schistosomiasis, human African trypanosomiasis, leishmaniasis, Chagas disease, yellow fever, Japanese encephalitis and onchocerciasis. The burden of these diseases is highest in tropical and subtropical areas, and they disproportionately affect the poorest populations. Major outbreaks of dengue, malaria, chikungunya, yellow fever and Zika have afflicted populations, claimed lives and overwhelmed health systems in many countries. Diseases such as chikungunya, leishmaniasis and lymphatic filariasis cause chronic suffering, lifelong morbidity, disability and occasional stigmatization. Distribution of vector-borne diseases is determined by a complex set of demographic, environmental and social factors. Global travel and trade, unplanned urbanization and climate change have introduced vector-borne diseases to new countries. 7.3 Vector-borne diseases, according to their vector The table contains a non-exhaustive list of vector-borne diseases, ordered according to the vector by which they are transmitted. The list also includes the type of pathogen that causes the disease in humans. Water plays a key role in the lifecycle of most vectors. Thus, the transmission of many vector- borne diseases is seasonal as there is a relationship between rainfall and the existence of breeding sites. Temperature and relative humidity are also critical factors, limiting the distribution of vectors by altitude and latitude. Travellers are at lower risk of exposure to some vector-borne diseases in urban centres, especially if they sleep in air-conditioned rooms. They may, however, be exposed to the Aedes mosquito vectors of dengue, chikungunya, and Zika viruses which are frequent in urban centres in tropical countries and which bite mostly during the day. Travellers to rural areas 7. Vector-borne diseases 23 Vector Disease caused Type of pathogen Mosquito Aedes Chikungunya Dengue Lymphatic filariasis Rift Valley fever Yellow fever Zika Virus Virus Parasite Virus Virus Virus Anopheles Lymphatic filariasis Malaria Parasite Parasite Culex Japanese encephalitis Lymphatic filariasis West Nile fever Virus Parasite Virus Aquatic snails Schistosomiasis (bilharziasis) Parasite Blackflies Onchocerciasis (river blindness) Parasite Fleas Plague (transmitted from rats to humans) Tungiasis Bacteria Ectoparasite Lice Typhus Louse-borne relapsing fever Bacteria Bacteria Sandflies Leishmaniasis Sandfly fever (phlebotomus fever) Parasite Virus Ticks Crimean-Congo haemorrhagic fever Lyme disease Relapsing fever (borreliosis) Rickettsial diseases (eg: spotted fever and Q fever) Tick-borne encephalitis Tularaemia Virus Bacteria Bacteria Bacteria Virus Bacteria Triatome bugs Chagas disease (American trypanosomiasis) Parasite Tsetse flies Sleeping sickness (African trypanosomiasis) Parasite or to areas with poor hygiene and sanitation are usually at higher risk of exposure to disease vectors, and personal protection is therefore essential. Evening and night-time activities outdoors may increase exposure to malaria vectors. 24 International travel and health | Module 2: Environmental health risks 7.4 Protection against vectors Travellers may protect themselves from mosquitoes and other vectors by the means outlined below. Insect repellents are substances applied to exposed skin or to clothing to prevent human/vector contact. Repellents should be used in strict accordance with the manufacturers’ instructions and the dosage must not be exceeded, especially for young children and pregnant women. The active ingredient in a repellent repels insects but does not kill them. Travellers should choose a repellent containing DEET (N,N-diethyl-3- methylbenzamide), IR3535 (3-[N-acetyl-N-butyl]-aminopropionic acid ethyl ester) or icaridin (1-piperidinecarboxylic acid, 2-(2-hydroxyethyl)-1-methylpropylester). Insect repellents should be applied to provide protection at times when insects are biting. Care must be taken to avoid the repellent coming into contact with mucous membranes; insect repellents should not be sprayed on the face, applied to the eyelids or lips, or applied to sensitive, sunburned or damaged skin or deep skin folds. Always wash the hands after applying the repellent. Repeated applications may be required every 3–4 hours, especially in hot and humid climates when sweating may be profuse. Mosquito nets are excellent means of personal protection while sleeping. Nets can be used either with or without insecticide treatment. However, treated nets are much more effective. Pretreated nets may be commercially available. Nets should be strong and have a mesh size no larger than 1.5 mm. The net should be tucked in under the mattress, after ensuring that it is not torn and that there are no mosquitoes inside. Nets for hammocks are available, as are nets for cots and small beds. Mosquito coils are the best-known example of insecticide vaporizer, usually with a synthetic pyrethroid as the active ingredient. A more sophisticated product, which requires electricity, is an insecticide mat that is placed on an electrically heated grid, causing the insecticide to vaporize. Battery-operated vaporizers are also available. Such devices can also be used during the daytime if necessary. Aerosol sprays intended to kill flying insects are effective for quick knockdown and killing. Indoor sleeping areas should be sprayed before bedtime. Treating a room with an insecticide spray will help to free it from insects, but the effect may be short-lived. Spraying before bedtime, combined with the use of a vaporizer or a mosquito net is recommended. Aerosol sprays intended for crawling insects (e.g. cockroaches and ants) should be sprayed on surfaces where these insects walk. Protective clothing can help at times of the day when vectors are active. The thickness of the material is critical. Insect repellent applied to clothing is effective for longer than it may be on the skin. Extra protection is provided by treating clothing with permethrin or etofenprox to prevent mosquitoes from biting through clothing. In tick- and flea-infested areas, the feet should be protected by appropriate footwear and by tucking long trousers into the socks. Such measures are further enhanced by application of repellents to the clothing. • Travellers camping in tents should use a combination of mosquito repellents and screens. The mesh size of tent screens often exceeds 1.5 mm, meaning that special mosquito screens are necessary. • Screening of windows, doors and eaves reduces exposure to flying insects. Accommodation with these features should be sought where available. • Air-conditioning is a highly effective means of keeping mosquitoes and other insects out of a room as long as the room has no gaps around windows or doors. In air- conditioned hotels, other precautions are not necessary indoors. 7. Vector-borne diseases 25 DENGUE and severe dengue DENGUE Flu-like illness SEVERE DENGUE Life-threatening complications Fastest spreading, epidemic-prone infectious diseases of actual burden in Asia Causes BILLION US $ in economic loss Estimated 390 MILLION dengue virus infections / year KILLS one person every 12 minutes Leading cause of death in children Threatens 4 BILLION people in 128 countries Virus transmitted through the bite of infected FEMALE Aedes MOSQUITOES Bite during the DAY Breed in STAGNANT WATER in artificial containers High FEVER > 40°C / 104°F Severe headache Pain behind the eyes Nausea and vomiting Swollen glands / rash on the body Muscle, joint pains and chills Hospitalization required for symptoms of severe dengue NO specific tratment for infection MOSQUITO BITE PREVENTION Screening of windows and doors – home and office APPLY MOSQUITO REPELLENT and use personal protective measures (aerosols, coils, mats etc) as per label instructions Wear LIGHT COLOURED clothing and, long-sleeved shirts and trousers Medication can be taken to control symptoms Warning signs of SEVERE DENGUE include severe bleeding and respiratory distress SIGNS and SYMPTOMS MOSQUITO PROLIFERATION CONTROL REMOVE/AVOID all stagnant water COVER all water tanks Live in URBAN ENVIRONMENTS in and around houses HOW DO PEOPLE GET INFECTED? 70% Mosquito-borne VIRAL infection leading to: 26 International travel and health | Module 2: Environmental health risks Further information • Vector-borne diseases (2020). [key facts]. Geneva: World Health Organization (https:// www.who.int/news-room/fact-sheets/detail/vector-borne-diseases). • Chikungunya (2022). [key facts]. Geneva: World Health Organization (https://www.who. int/news-room/fact-sheets/detail/chikungunya). • Zika virus (2022). [key facts]. Geneva: World Health Organization (https://www.who.int/ news-room/fact-sheets/detail/zika-virus). • Zika virus disease [overview]. Geneva: World Health Organization (https://www.who.int/ health-topics/zika-virus-disease#tab=tab_1). • Will I catch Zika if I travel? [poster]. Geneva: World Health Organization (https:// cdn.who.int/media/images/default-source/infographics/zika/zika-will-i-catch-zika. jpg?sfvrsn=6e42280f_1). • Dengue and severe dengue (2023). [key facts]. Geneva: World Health Organization (https://www.who.int/news-room/fact-sheets/detail/dengue-and-severe-dengue). • Crimean-Congo haemorrhagic fever (2023). [key facts]. Geneva: World Health Organization (https://www.who.int/news-room/fact-sheets/detail/crimean-congo- haemorrhagic-fever). • Rift Valley fever. [overview]. Geneva: World Health Organization (https://www.who.int/ health-topics/rift-valley-fever • Yellow fever (2023). [key facts]. Geneva: World Health Organization (https://www.who.int/ news-room/fact-sheets/detail/yellow-fever). • Yellow fever [overview]. Geneva: World Health Organization (https://www.who.int/health- topics/yellow-fever#tab=tab_1). • WHO position papers on Yellow fever. Geneva: World Health Organization (https://www. who.int/teams/immunization-vaccines-and-biologicals/policies/position-papers/yellow- fever). • Japanese encephalitis (2019). [key facts]. Geneva: World Health Organization (https:// www.who.int/news-room/fact-sheets/detail/japanese-encephalitis). • WHO position papers on Japanese encephalitis. Geneva: World Health Organization (https://www.who.int/teams/immunization-vaccines-and-biologicals/policies/position- papers/japanese-encephalitis). • Leishmaniasis (2023). [key facts]. Geneva: World Health Organization (https://www.who. int/news-room/fact-sheets/detail/leishmaniasis). • Lymphatic filariasis (2023). [key facts]. Geneva: World Health Organization (https://www. who.int/news-room/fact-sheets/detail/lymphatic-filariasis). • Malaria (2023). [key facts]. Geneva: World Health Organization (https://www.who.int/ news-room/fact-sheets/detail/malaria). • Malaria [overview]. Geneva: World Health Organization(https://www.who.int/health- topics/malaria#tab=tab_1). • International travel and health. Chapter 7 – malaria (2020 update). Geneva: World Health Organization (https://cdn.who.int/media/docs/default-source/travel-and- health/9789241580472-eng-chapter-7.pdf?sfvrsn=8be7067_13). • Onchocerciasis (2022). [key facts]. Geneva: World Health Organization (https://www.who. int/news-room/fact-sheets/detail/onchocerciasis). 7. Vector-borne diseases 27 • Chagas disease (American tripanosomiasis) [overview]. Geneva: World Health Organization (https://www.who.int/health-topics/chagas-disease#tab=tab_1). • Human African trypanosomiasis (sleeping sickness) [overview]. Geneva: World Health Organization (https://www.who.int/health-topics/human-african- trypanosomiasis#tab=tab_1). • Trypanosomiasis, human African (sleeping sickness) (2023). [key facts]. (https://www. who.int/news-room/fact-sheets/detail/trypanosomiasis-human-african-(sleeping- sickness). • Plague (2022). [key facts]. Geneva: World Health Organization (https://www.who.int/ news-room/fact-sheets/detail/plague). Malaria in United Republic of Tanzania – 1993 A young boy lies under a mosquito net in Namwa Wala village. Bednets impregnated with insecticide have been shown to reduce malaria deaths. Villagers here also impregnate reed mats and hang them on the walls to help kill mosquitos. Country: United Republic of Tanzania Date created: 1993 Credit: WHO / TDR / Andy Crump Copyright notice: © WHO / TDR / Andy Crump Reference: HQ78349