Short Note
Dengue Fever/Dengue Haemorrhagic Fever in Chandigarh (North India) R.K. Rathoa , B. Mishraa, S. Kumara and S. Varmab a
Department of Virology, Postgraduate Institute of Medical Education and Research, Chandigarh-160012, India
b
Department of Internal Medicine, Postgraduate Institute of Medical Education and Research, Chandigarh-160012, India
Dengue fever (DF) is currently the most important mosquito-borne arboviral infection of humans. The dengue virus, with its four serotypes, has established endemicity in most tropical and subtropical regions, putting approximately 2.5 billion people at risk globally. [1,2] The outbreaks of dengue haemorrhagic fever/dengue shock syndrome (DHF/DSS) have occurred in several places in India[3] such as Delhi,[4] Ludhiana,[5] Tamil Nadu[6] and Maharashtra.[7] We investigated the outbreaks of DF/DHF that occurred during 1996 and 1999 in Chandigarh (north India). Acute-phase blood samples of 338 clinically suspected DF/DHF patients were tested for dengue-specific IgG antibodies using dengue blot assay (Genelabs Diagnostics, Singapore) and for IgM antibodies using µcapture ELISA (Pan-Bio, Australia) during 1996 and 1999. Fifty samples were also tested for dengue antibodies by the haemagglutination inhibition (HI) test using the antigen extracted from the infected mouse brain (DENV-2 prototype) following the method described by Lenette et al.[8] Dengue virus antigen was detected in adult female Aedes aegypti mosquitoes by head squash preparation by indirect immunofluorescence test using prototype DENV-2 polyclonal hyperimmune
serum raised in rabbit (in-house standardized) and anti-rabbit IgG-FITC conjugate (Sigma Aldrich, USA). Of the total of 338 patients, 50 patients were investigated during the outbreak in 1996 and 288 in 1999. The male to female ratio was 2.3:1. Children less than 10 years of age constituted 17.6% of the total number of patients, while 20.4%, 29.3% and 18.8% patients were in the age groups of 11-20, 2130 and 31-40 years respectively. Denguespecific IgM and IgG was found positive in 46.7% (158/338) and 73.6% (198/269) patients respectively. The year-wise dengue IgM and IgG positivity is shown in Table 1. The number of DF/DHF patients showing primary and secondary immune response is shown in Table 2. Dengue virus antigen was demonstrated in Aedes aegypti mosquito. The HI antibodies to dengue virus were found at >1:80 titre in all patients, whereas the titre of antibodies to Japanese encephalitis virus and West Nile virus was ≤10 in all patients. One of the largest outbreaks in north India occurred in Delhi and adjoining areas in 1996.[4] The outbreak lasted from September to November. DF/DHF reappeared within three years in a cyclical trend with a greater
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DF/DHF in Chandigarh, India
Table 1: Serological diagnosis in patients of clinically suspected DF/DHF in 1996 and 1999 Year 1996 1999 Total Dengue IgG antibodies Tested 50 219 269 Positive 43 (86.0%) 155 (70.8%) 198 (73.6%) Dengue IgM antibodies Tested 50 288 338 Positive 38 (76.0%) 120 (41.7%) 158 (46.7%)
Table 2: Primary and secondary immune responses in patients of DF/DHF (n=269) Groups Dengue antibody No. of patients (%) in the year 1996 I II III IV Total IgM+ve, IgG-ve IgM+ve, IgG+ve IgM-ve, IgG+ve IgM-ve, IgG-ve 3 (6.0) 33 (66.0) 11 (22.0) 3 (6.0) 50 1999 12 (5.5) 64 (29.2) 90 (41.1) 53 (24.2) 219 15 (5.6) 97 (36.0) 101 (37.5) 56 (20.8) 269 Total (%)
Primary infection (Group I) = 15/269 (5.6%) Secondary infection (Group II) = 97/269 (36%) Prior exposure to dengue infection (Group III) = 101/269 (37.5%)
propensity (288 vs. 50 patients), indicating an upsurge in the virus transmission in this region. These observations suggested that dengue had established the seasonal and cyclical pattern in this part of the country as had been observed in other South-East Asian Countries.[2] The 1999 epidemic was one of the largest DF/DHF outbreak reported in Chandigarh, which is comparatively a cleaner and more hygienic city. An increase in the population density and increased construction activities as part of urbanization over the years have led to inadequate water supply, leading to construction of overhead water storage
tanks in most houses and also increase in water storage practices. These factors have contributed to the breeding of the prime vector Ae. aegypti throughout the year.
Acknowledgements The authors acknowledge the scientific help rendered by Dr Raminder Grover, former Assistant Professor, Dept. of Virology, P.G.I.M.E.R, Chandigarh, towards the completion of this study.
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DF/DHF in Chandigarh, India
References [1] Gubler DJ. World distribution of dengue, 1996. Dengue Bulletin 1996,20:1-4. [2] Gubler DJ, Clark GG. Dengue/dengue hemorrhagic fever: the emergence of a global health problem. Emerg Infect Dis 1995 AprJun;1(2):55-7. [3] Bandopadhyay S, Jain DC, Datta KK. Reported incidence of dengue/dengue haemorrhagic fever in India 1991-1995. Dengue Bulletin 1996;20:33-34. [4] Dar L, Broor S, Sengupta S, Xess I, Seth P . The first major outbreak of dengue hemorrhagic fever in Delhi, India. Emerg Infect Dis 1999 Jul-Aug;5(4):589-90. [5] Kaur H, Prabhakar H, Mathew P , Marshalla R, Arya M. Dengue hemorrhagic fever outbreak in October-November, 1996 in Ludhiana, Punjab, India. Indian J Med Res 1997 Jul;106:1-3. [6] Victor TJ, Malathi M, Gurusamy D, Desai A, Ravi V, Narayanasamy G, Anuradha L, Rani C, Krishnamurthy P . Dengue fever outbreaks in two villages of Dharmapuri district in Tamil Nadu. Indian J Med Res 2002 Oct;116:133-9. [7] Mehendale SM, Risbud AR, Rao JA, Banerjee K. Outbreak of dengue fever in rural areas of Parbhani district of Maharashtra (India). Indian J Med Res 1991 Jan;93:6-11. [8] Lenette EH, Schmidt NJ. Diagnostic procedures for viral, rickettsial and chlamydial infections. 5th ed. Washington DC, American Public Health Association Inc. 1979.
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