Dengue Outbreak 2000 in Bangladesh: From Speculation to Reality and Exercises by
Emran Bin Yunus*, A Mannan Bangali, M Ataul Huq Mahmood, M Mushfiqur Rahman, A R Chowdhury and K R Talukder Dengue Study Group, Disease Control Directorate, Directorate General of Health Services Mohakhali, Bangladesh
Abstract An outbreak of DF/DHF occurred in three major cities and 17 other towns of Bangladesh in June 2000. The total number of cases recorded was 5551: DF 4385 (98.9%) and DHF 1166 (21.1%), with 93 deaths (1.6%). In 1996-97, a well-designed hospital-based descriptive study revealed evidence of dengue infection in a significant proportion of febrile cases (13.7%) with three serotypes of the dengue virus (DEN-1, DEN-2 and DEN-3) where the secondary infection pattern outnumbered the primary type. These findings confirmed the continuation of transmission and the potential for future outbreaks. An entomological survey in the same city revealed the presence of the vector Aedes aegypti with a Bretaeu index of 18.2% during this period. When the outbreak became a reality, initially the people, the medical profession and the control programme implementers were in a state of confusion due to the lack of knowledge, skill and attitude necessary for its containment. Soon the National Control Programme developed appropriate plans of action and instruments of operation in collaboration with WHO to tackle the situation in all spheres with successful operationalization. The outcome was the development of national guidelines for the clinical management of dengue syndrome, training of doctors, reorientation of specialists, entomological mapping, documentation of cases, operational studies for testing case definitions and collection of sero-evidences as well as empowering the community to ensure their appropriate participation for prevention and control. Besides successes there were failures too. Keywords: Dengue outbreak, case management, entomological assessment, lessons learnt.
Introduction Dengue is a common communicable infectious disease of which the frequency is next only to malaria globally(1). The new pattern of dengue, dengue haemorrhagic * For correspondence: emran@spnetctg.com
fever (DHF), appeared in Thailand in the 1950s and almost invaded all the countries in the South-East Asian Region. It has now become a public health problem of great concern. Outbreaks of DF and DHF have now become a regular cyclical phenomenon
Dengue Bulletin – Vol 25, 2001
15
Dengue Outbreak 2000 in Bangladesh: From Speculation to Reality and Exercises
with increasing incidence, morbidity and mortality in almost all the countries surrounding Bangladesh which have similar socio-economic, climatic and geographical features. Bangladesh was thought to be free from dengue except some sporadic reports of incidence since 1965(2). As a result the people, the medical profession and the disease control programme were not acquainted with and aware about dengue in any of its different aspects like diagnosis, management, prevention and control. The dengue outbreak of 2000 changed the notion and other attributes related to dengue. The evidence of dengue infection was confirmed earlier by a well-designed descriptive study done in 1996-97 that was sponsored by the Integrated Control of Vector-Borne Diseases (ICOVED) Project of the Directorate-General of Health Services in collaboration with WHO(3). Besides confirming the presence of dengue, the study also unveiled some evidence of the future outbreak potential. In 2000 a major outbreak occurred in Bangladesh, mostly in three large cities with reports also coming in from 17 other towns. During this outbreak many clinical and public health exercises were performed, documentation was recorded and measures were taken to prepare for the future along with developing some scientific activities.
paediatric age group with haemagglutination inhibition test (HIT) of paired sera one week apart. Out of the 255 paired samples 35(13.7%) were found to be positive with evidence of more than one serotype of dengue virus, where secondary infection outnumbered the primary. An entomological survey vis-a-vis seorological documentation revealed the presence of the vector Aedes aegypti with a Breteau index of 18.2 (Table 1). Table 1. ICOVED endeavours: Sero-survey and Entomological survey A. Sero-survey in Chittagong Medical College Hospital(3) Total Age Male Positive HIT Primary Secondary Primary/Secondary DEN-1 Serotype DEN-2 Serotype DEN-3 Serotype DEN-4 Serotype DEN-2+DEN-3 Serotypes DEN-2+DEN-4 Serotypes DEN-3+DEN-4 Serotypes Vector House index Container index Breteau index 255 Mean: 7.1 (± 02.8) Years 60.7% 35 (13.7%) 05 (14.3%) 13 (37.1%) 17 (48.6%) 00 (00.0%) 01 (02.9%) 16 (47.7%) 10 (28.6%) 01 (02.9%) 04 (11.4%) 03 (08.6%)
The endeavours of ICOVED The 1995 endeavours of ICOVED included a 'sero-epidemiological study for dengue and dengue haemorrhagic fever, undertaken at the Chittagong Medical College Hospital (CMCH) over a period of about one year during 1996-97 among febrile patients of the 16
B. Entomolocal survey in Chittagong city(4) Aedes aegypti 18.2% 03.4% 18.2 Dengue Bulletin – Vol 25, 2001
Dengue Outbreak 2000 in Bangladesh: From Speculation to Reality and Exercises
The aforementioned ICOVED endeavours confirmed the presence of dengue cases, the vector and a possible continuation of the disease transmission. From these results at that time it was speculated that possibly a big outbreak was likely to occur within a few years.
Clinical pattern of dengue cases(6) During the early part of the outbreak, members of the Malaria Research Group documented the clinical and epidemiological features of haemorrhagic fever cases admitted in the Medical and Paediatrics units of the CMCH during the month of August 2000. A total of 112 (83%) cases in adult Medical and 23 (17%) cases in Paediatrics units were recorded. The categorization of cases as per WHO case definition DF, DHF-I, DHF-II, DHF-III and DHF-IV were 24(21%), 80(71%), 5(5%), 1(1%) and 2(2%) respectively. Seventy-three percent of these were males and the over all case fatality was 2.7%. The mean age (years), duration of illness (days), duration of fever (days), duration of rash (days), rash appearance day (day), afebrile period (days) were 25.4, 8.1, 6, 3.3, 5.5 and 2.0 respectively. The most frequent features were: high fever (100%), severe headache (80%), external bleeding (79%), severe bodyache (64%), red eye (56%), eyeache (34%), altered bowel (33%), cough (30%), and abdominal pain (26%). Tourniquet test was done in 46 cases with positive result in 60%. The frequency of cutaneous bleeding were 64%, haemorrhage 79%, mean platelet count 96900 mm3, PCV 49.1%, total leucocyte 6900mm3 and haemoglobin 12 g/dl. Rapid dengue test was done in 43 cases with overall positivity 74.4%. This documentation revealed that there were more adult than pediatric patients.
The 2000 Outbreak(5) From June 2000 onwards, the spell and the toll of the dengue outbreak began to occur with cases of haemorrhagic fever filling the city hospitals and clinics mostly in Dhaka, Chittagong and Khulna. Cases were reported from 17 other cities as well. The outbreak lasted till December 2000. The total number of cases recorded were 5551: DF 4385 (78.9%), DHF 1166 (21.1%) with 93 (1.6%) deaths (Table 2). The proportion of DHF was less in Dhaka city, and the mortality was found to be less in Dhaka and Chittagong. The reason for this was the later is possibly that better case management facilities were available here than in other cities. The presence of more DF cases in Dhaka was a harbinger of more DHF cases there later. Table 2. Reported cases of DF/DHF from July-December 2000 Cities Dhaka Chittagong Khulna Others: 17 cities Total Total 3964 0771 0428 0388 5551 DF (%) 3383 (85.3) 0473 (61.3) 0259 (60.5) 0270 (66.7) 4385 (78.9) DHF (%) 0581 (14.7) 0298 (38.7) 0169 (39.5) 0118 (33.3) 1166 (21.1) Deaths (%) 51 (01.3) 15 (01.9) 14 (03.3) 13 (03.3) 93 (01.6)
Exercises for management of cases Within the first week of the report of the dengue outbreak the Disease Control 17
Dengue Bulletin – Vol 25, 2001
Dengue Outbreak 2000 in Bangladesh: From Speculation to Reality and Exercises
Directorate initially arranged the collection of WHO guidelines for case management and test-kits for dengue serology and established reporting portals and a set-up for the documentation of cases. This effort was followed by training of doctors and orientation of specialists on dengue case management, formulation of National Guidelines for Clinical Management of Dengue Syndrome by customization of WHO guidelines and attaining a general consensus, entomological survey, plus initiation of clinical and virological documentations. Around 300 doctors were trained, 150 specialists were reoriented and a general national consensus on a uniform system of case definition and management was attained. The help of leading experts on dengue for its clinical and other aspects was ensured as well. All these efforts were collaborated by WHO.
In all major cities entomological indices were present in a significant way (Table 3). But proper assessments and implications could not be inferred because of lack of earlier data and absence of critical threshold values.
Continuing activities The National Control Programme has now adopted some activities on a continuing basis. These are: prospective serological survey in hospitals of two major cities plus a study for collecting febrile phase sera of eligible cases for viral isolation and PCR. In both the studies entries of national case definition will be tested in terms of specificity, sensitivity and predictive values in an attempt to choose the early markers for use in national control programme operations besides clinical use. In addition, entomological data collection, training and reorientation of doctors and health-care providers plus community empowering activities are also being continued.
Entomological survey during 2000 outbreak During the 2000 outbreak a comprehensive entomological survey was conducted in major cities of Bangladesh to document the disease pattern and as a requirement for future preparedness. Table 3. Entomological survey data Vector: Aedes aegypti(7) Cities House Index (%) 46 22 40 Container Index (%) 37 13 31 Breteau Index 50 18 42
Discussion Dengue was not a matter of clinical concern or a public health issue till the outbreak of 2000. But there was evidence that dengue was present with outbreak potential. When the outbreak became a reality it changed many attitudes: clinicians’ views and activities; the perception and operational plans of national control programmes; attitudes of civil society and community empowerment; and capacity development. The pattern of the disease emergence in Bangladesh was not different from that in the neighbouring countries as well as the clinical Dengue Bulletin – Vol 25, 2001
Dhaka Chittagong Khulna Others: 17 cities (Mode, Median, Mean)
1.6, 14.5, 20.3
23, 19.9, 19.9
1.6, 18.7, 23.8
18
Dengue Outbreak 2000 in Bangladesh: From Speculation to Reality and Exercises
issues involved except the patients’ age. Though dengue is mostly a paediatric disease, but in this outbreak most cases were adults. This fact was observed earlier also(8). This is possibly because of the absence of cumulative acquired immunity. The dengue outbreak might be considered a blessing in disguise. The most encouraging aspect was the general community’s response to it. Though initially there was panic, accusation and confusion, but for the first time in this country the community gave a tremendous response which is unmatched for any other infectious disease. People from all sections of the society, media, and other professions responded in a very pragmatic way to create and take preventive actions to combat dengue. The role of the public agencies was also relatively prompt and effective. For the first time in the country health agencies were able to disseminate the knowledge, skills and resources to effectively contain the problem. Moreover, health agencies were also able to develop a consensual 'National Guideline for Clinical Management of Dengue Syndrome' in an effort to make the clinical management uniform, effective, user-friendly and costeffective, which was devoid of any confusions and controversies. In other words, an appropriate tool for the early diagnosis and prompt treatment of dengue was made available which was the only effective tool for prevention and control(9). The control programme’s terminology ‘dengue syndrome’ as adopted in the National Guideline to avoid confusion of the overlapping nature of the various manifestations of dengue provided appropriate emphasis on the nature and course of the disease and the measures to be Dengue Bulletin – Vol 25, 2001
taken. This received due endorsement from all concerned. It was due to these efforts that despite the large number of cases the mortality was kept low. But there were failures too. One needs to understand the failures in order to avoid making similar mistakes in the future. As medical professionals we should accept the fact that we failed to respond properly at an appropriate time when the evidences were available a few years back. With the emergence and reporting of the disease we could have easily collected the relevant information, knowledge and skill through the information super highway and other linkages. Our general and specialized bodies could then have developed and disseminated guidelines for disease management as well as documentation tools, templates and linkages promptly. By this we could have easily avoided the management controversies and could have had a strong grip over the situation, not to speak of the trust of the people. Through this basic approach we could also guide the people and government agencies as well to choose and employ the most appropriate measures. In reality the reverse happened. We missed a golden opportunity to clinically document an outbreak afresh in our land. This outbreak gave rise to certain issues which need to be resolved. The first and foremost is to find out the critical threshold of the entomological indices of the vector. The second is: what are the most appropriate measures for control and prevention. For this purpose there is a need to establish appropriate clinical markers and their correlation in terms of specificity, sensitivity and predictive values for early 19
Dengue Outbreak 2000 in Bangladesh: From Speculation to Reality and Exercises
diagnosis and prompt treatment like those developed in Thailand(10). The next issue is appropriate community empowerment and participation. The track record of dengue reveals that it enters a country not to leave. In countries where dengue has emerged as a public health problem, it has remained so, proving thereby that it is not merely a clinical issue. The toll taken by dengue is enormous in all respects and its characteristics are unique in many ways(11). So, from the dengue outbreak in 2000 we need to learn evidence-based lessons(10), consolidate them in proper ways and analyse them in a scientific format to prepare appropriate plans and programmes for effective implementation to combat the infection in the future. Moreover, this should prompt us to be more proactive. In short, the public and the medical profession should be oriented to 'learn to live with dengue' and this orientation process should be coordinated by the National Control Programme through creating awareness and taking action, the first target to be to reduce mortality and the next to reduce morbidity.
3.
Yunus EB, Banu D, Chowdhury MJH, Talukder KR, Bangali AM. Report on ser-epidemiological study of dengue & dengue haemorrhagic fever, ICOVD Project, Directorate General of Health Services, 1998. Knudsen AB. Summary Report on WHO-STC, 20 August - 03 September 1997. Malaria and Parasitic Diseases Control Unit, Directorate General of Health Services & WHO. Dengue Register, Disease Control Directorate, Directorate General of Health Services, Dhaka. Yunus EB, Rahman MR, Hossain MA, Samad R, Faiz MA. Evidence of Dengue from Chittagong. Program Book, Second International Meeting on Tropical Medicine Update, Bangladesh Association for Advancement of Tropical Medicine, Chittagong, 2001. Chowdhury AR. Report on the entomological survey 2000. Malaria and Parasitic Diseases Control Unit, Directorate General of Health Services, Dhaka. Prasittisuk C, Andjaparidze A. Dengue Haemorrhagic Fever Prevention and Control Activities in South-East Asia Region. Dengue Bulletin, 1996, 20: 24-30. Yunus EB (Ed). National Guidelines for Clinical Management of Dengue Syndrome. Malaria and Parasitic Diseases Control Unit, DGHS, MOH, Bangladesh & WHO; Dhaka. First Edition, 2001.
4.
5. 6.
7.
8.
9.
References 1. 2. Gubler DJ. Dengue and dengue haemorrhagic fever. Clin. Microbiol. Rev., 1998, 11:480-96 Aziz MA, Graham R, Gregg MB. 'Dhaka Fever'. Pakistan Journal of Medical Research, 1967, 6: 8392.
10. Kalayanarooj S, Nimmannitya S, Suntayakorn S, Vaughn DW, Nisalak A, Green S, Chansiriwongs V, Rothman A, Ennis FA. Can doctors make an accurate diagnosis of dengue infection at an early stage? Dengue Bulletin, 1999, 23: 19. 11. Graham K. Readers’ Digest, January 2001, 81.
20
Dengue Bulletin – Vol 25, 2001