WHO Regional Office for Europe update on avian influenza A(H7N9) virus: situation update 1, 23 April 2013

WHO Regional Office for Europe update on avian influenza A (H7N9) virus Situation update 1: 23 April 2013 Address requests about publications of the WHO Regional Office for Europe to: Publications WHO Regional Office for Europe UN City, Marmorvej 51 DK-2100 Copenhagen Ø, Denmark Alternatively, complete an online request form for documentation, health information, or for permission to quote or translate, on the Regional Office web site (http://www.euro.who.int/pubrequest). © World Health Organization 2013 All rights reserved. The Regional Office for Europe of the World Health Organization welcomes requests for permission to reproduce or translate its publications, in part or in full. 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Situation update 1: 23 April 2013 page 1 CONTENTS Page 1) Situation update ...................................................................................................... 2  2) WHO risk assessment as of 13 April 2013 .................................................................. 6  3) Recommendations ................................................................................................... 6  4) Key references and guidance .................................................................................... 8  Situation update 1: 23 April 2013 page 2 This update summarizes the available information and recommendations made by WHO about human infections with avian influenza A(H7N9) virus in China for Member States of the WHO European Region. WHO/Europe is coordinating its activities related to this outbreak with the European Commission, the European Centre for Disease Prevention and Control (ECDC), the EuroFlu network (www.euroflu.org) and the Community Network of Reference Laboratories for Human Influenza in Europe (CNRL). As of 23 April 2013, this update will be posted every Tuesday in English and (with a possible slight delay for translation) in Russian and will include:  a situation update;  latest WHO risk assessment (this week as of 13 April 2013);  recommendations; and  key references and guidance. 1) Situation update On 31 March 2013, the health authorities of China notified WHO of three laboratory-confirmed human cases of avian influenza A(H7N9) virus infection. These cases reported from China are the first known cases of human infection with A(H7N9). Since that time China has continued to report new human cases. As of 23 April 2013, 108 laboratory confirmed human cases with A(H7N9) virus including 22 fatalities in China have been reported from four provinces (Anhui, Henan, Jiangsu and Zhejiang) and two municipalities (Beijing and Shanghai). The following map, table of confirmed cases and epidemiological curve were published by WHO headquarters in the weekly report Number of confirmed human cases for avian influenza A(H7N9) reported to WHO as of 16 April 2013.1 1 www.who.int/influenza/human_animal_interface/influenza_h7n9/Data_Reports/en/index.html, accessed  22 April 2013  WHO/Europe emphasizes the need for Member States to maintain the capacity to detect any unusual health event, including those that may be associated with a new subtype of influenza A which should be notified to WHO in accordance with the International Health Regulations (2005). Human health and animal health sectors should maintain close and systematic interactions for timely exchange of information and to conduct joint risk assessments for the prevention and control of zoonotic diseases, as necessary. This work should be done under the relevant components of multi-hazard plans for preparedness and response to public health events. Situation update 1: 23 April 2013 page 3   Situation update 1: 23 April 2013 page 4   See also: Disease Outbreak News, WHO headquarters, www.who.int/csr/don/en/index.html    Infections with avian influenza A(H7N9) virus and epidemiology  Although these cases reported from China are the first known cases of human infection with an avian influenza A(H7N9) virus, this virus is one subgroup among the larger group of influenza A(H7) viruses which have previously been reported to cause sporadic human infections associated with poultry outbreaks. These infections in humans have mainly resulted in mild disease (e.g. conjunctivitis and mild upper respiratory symptoms). In contrast, many of the reported cases of human infection with avian influenza A(H7N9) virus have resulted in severe disease and deaths. The source of infection and the mode of transmission for the A(H7N9) virus are currently unknown. Small clusters that may indicate limited human-to-human transmission have been detected, but there is no evidence of sustained, efficient human-to-human transmission. As of 21 April 2013, more than 1000 close contacts of confirmed cases and health care workers providing care for patients infected with A(H7N9) have been monitored by public health authorities for infection and have not developed clinical disease. This virus has now also been isolated from poultry (including ducks and pigeons) in live bird markets in some areas of China. National and international human and animal health authorities are working hard to determine the source of infection. This work is complicated by the fact that so far this virus has not been associated with reports of severe disease in poultry and appears to be a low pathogenicity avian influenza (LPAI) virus.2 Investigations are ongoing to determine if any animal reservoir of this virus exists, including other domestic and wild bird species, and mammalian species such as swine. 2 http://www.fao.org/avianflu/documents/key_ai/key_book_ch2.htm, accessed 22 April 2013  Situation update 1: 23 April 2013 page 5 Clinical presentation The main clinical feature among most avian influenza A(H7N9) patients has been respiratory disease resulting in severe pneumonia. Symptoms include fever, cough and shortness of breath. Many of the reported patients have required intensive care and mechanical ventilation. Only a few of the cases have reported mild disease. Investigations are ongoing to determine the full spectrum of disease associated with avian influenza A(H7N9) infection. Virology  The virus contains a group of avian influenza virus genes from three different avian influenza viruses. The gene for the haemagglutinin or HA protein belongs to a Eurasian group of H7 avian influenza viruses, but is genetically distinct. The gene for the neuraminidase or NA protein is similar to avian A(H11N9) viruses found in South Korea in 2011, in Hongze, Jiangsu, China in 2010, and in the Czech Republic in 2005. The 6 genes coding for the internal proteins are similar to recent A(H9N2) viruses found in China and South Korea. Influenza A(H9N2) viruses are endemic in birds, including poultry, in Asia and elsewhere. Sequence analyses have shown that the genes of the influenza A(H7N9) viruses show signs of adaption to growth in mammalian species. These adaptations include an ability to bind to mammalian cell receptors, and to grow at temperatures close to normal body temperature of mammals (which is lower than that of birds).3 Treatment  Laboratory tests have shown that avian influenza A(H7N9) viruses are sensitive to the neuraminidase inhibitors class of influenza drugs (oseltamivir and zanamivir), but resistant to the antiviral drugs amantadine and rimantadine. When these drugs are given early in the course of illness, they have been found to be effective against seasonal influenza virus and influenza A(H5N1) virus infection. Treatment should still be initiated >48hrs after symptom onset if the patient has severe disease or is deteriorating. Prevention  No vaccine is currently available, but the viruses from the initial cases have been isolated and characterized with the aim to select candidate viruses for the vaccine. WHO and its partners will continue to characterize available viruses to identify the best candidate viruses to be used should a need for global vaccine production arise. While the source of infection and the mode of transmission have not yet been determined, it is prudent to follow good hygiene practices to prevent infection. For advice on infection prevention, contact with animals and food preparation, see: http://www.who.int/influenza/human_animal_interface/faq_H7N9/en/. Guidance for infection prevention and control in health care settings is available at http://www.who.int/csr/resources/publications/swineflu/WHO_CDS_EPR_2007_6/en/index.html. 3 http://www.euro.who.int/en/what-we-do/health-topics/communicable-diseases/influenza/publications/2013/public- health-relevant-virological-features-of-influenza-ah7n9-causing-human-infection-in-china, accessed 22 April 2013   Situation update 1: 23 April 2013 page 6 2) WHO risk assessment as of 13 April 2013 There are several critical gaps in information at this stage, including lack of knowledge about the animal reservoir(s) in which this virus is likely circulating, the main exposures and routes of transmission for humans and the current extent of spread of the A(H7N9) virus among animal and human populations. The current WHO risk assessment published on 13 April 2013, can be summarized as follows: I. Risk of the occurrence of further cases in the affected areas of China and other areas  The epidemiology of the A(H7N9) virus among animals, including the main reservoirs of infection among  animals and the extent of geographic spread, is not yet established. However, it is likely that most human  A(H7N9) infections so far are associated with contact to infected animals, and further human cases of  infection should be expected.   II. Risk of human‐to‐human transmission  There is no evidence of sustained human‐to‐human transmission. However, the two possible family  clusters suggest that limited human‐to‐human transmission may occur where there is close contact  between cases and other individuals, as occurs in families and, potentially, health care settings.  Moreover, the genetic changes seen among these viruses suggesting adaptation to mammals is of  concern, and further adaptation may occur.  III. Risk of international spread   At this time, there is no evidence to indicate international spread of this virus. It is possible that A(H7N9)  could be imported into other countries through infected travellers or animals, who may or may not  display symptoms. However, if the virus cannot sustain human‐to‐human transmission, as appears to be  the current situation, then extensive community spread is unlikely. 4  3) Recommendations WHO/Europe reemphasizes the need for Member States to maintain the capacity to detect any unusual health  event, including those that may be associated with a new subtype of influenza A, in accordance with the  International Health Regulations (2005). Human health and animal health sectors should maintain close and  systematic interactions for timely exchange of information and to conduct joint risk assessments for the   prevention and control of zoonotic diseases, as necessary. This work should be done under the relevant  components of multi‐hazard plans for preparedness and response to public health events.    Member States are encouraged to conduct national risk assessment, and update and implement the relevant  components of multi‐hazard plans for preparedness and response based on available information. A list of relevant  information sources is provided at the end of this document.   4 http://www.who.int/influenza/human_animal_interface/influenza_h7n9/RiskAssessment_H7N9_13Apr13.pdf, accessed 22 April 2013   Situation update 1: 23 April 2013 page 7   WHO does not advise the implementation of special screening at points of entry with regard to this event, nor  does it recommend that any travel or trade restrictions be applied.     Epidemiological and laboratory surveillance     Detailed surveillance guidance will be published by WHO in the near future. In the interim, Member States should  consider the possibility of human infection with A(H7N9) in the following situations:    any case of severe acute respiratory infection (SARI) in a patient that has travelled to an area with  confirmed avian influenza A(H7N9) in the last 7 days or has been in contact with a confirmed case of avian  influenza A(H7N9) during that time;   detection of a SARI cluster with unexplained etiology; or    any case of SARI detected in health care staff working in settings where SARI patients are being cared for.    In any of the above situations, clinical samples should be taken and analysed within the capacity of the national  laboratory system. All specimens that cannot be subtyped for influenza A and those with inconclusive or  unexpected subtyping results should be forwarded, immediately, to the WHO Collaborating Centre for  Reference and Research on Influenza, at the National Institute of Medical Research, London, United Kingdom for  additional testing.5     The investigation should include complete epidemiological and clinical information, for example: clinical signs and  symptoms, date of onset of symptoms, underlying clinical conditions, history of influenza vaccination, history of  treatment with oseltamivir or zanamivir, contact with animals, and history of travel, among others.     Guidance for establishing real‐time RT‐PCR assays for the detection of avian influenza A(H7N9) virus by National  Influenza Centres (NICs) in the WHO European Region has been developed by WHO/Europe in collaboration with  ECDC and the Community Network of Reference Laboratories for Human Influenza in Europe (CNRL) and has been  distributed to NICs. Protocols for real‐time RT‐PCR were published by WHO on 8 April 2013 on the Global Influenza  Programme website.6     Information for the public     Although there is no evidence of ongoing human‐to‐human transmission, it is important to implement the  following measures to prevent transmission of respiratory viruses:    Washing hands to reduce transmission.   Use of “respiratory etiquette” to help prevent transmission of the virus.   5 WHO Collaborating Centre for Reference and Research on Influenza at the National Institute of Medical Research, London, United Kingdomwww.who.int/influenza/gisrs_laboratory/collaborating_centres/list/en/.   6 PCR protocols: http://www.who.int/influenza/gisrs_laboratory/a_h7n9/en/, accessed 22 April 2013   Situation update 1: 23 April 2013 page 8  Individuals with flu‐like symptoms should avoid leaving their homes to go to work or to other public  places and seek medical advice if their condition worsens.     Preventive and control measures in the community should be disseminated in multiple languages to reach all  population groups.    4) Key references and guidance   WHO/Europe and other international organizations provide information about this event through the web sites  listed below. WHO/Europe is working to make key documents available in Russian. As documents become  available in Russian, they will be listed in this update. IHR National Focal Points will continue to receive information  through the Even Information System (EIS).     WHO headquarters   www.who.int/influenza/human_animal_interface/influenza_h7n9/en/index.html     WHO Regional Office for Europe   www.euro.who.int/en/what‐we‐do/health‐topics/A(H7N9)    European Centre for Disease Prevention and Control  http://ecdc.europa.eu/en/healthtopics/avian_influenza/Pages/index.aspx