Dengue outbreak in an Indo-Myanmar boarder area: epidemiological aspects and risk factors.

During October 2007, a large outbreak of suspected dengue fever (DF) was reported in Moreh township, Manipur: the first widespread outbreak in Northeast India. A cross sectional study was carried out in Moreh. The information on outbreak was collected and then described in time, place and person characteristics to arrive at aetiological hypotheses. Two hundred and eighty two serum samples were collected. Ninety one samples were reported positive for acute infection with dengue virus. Co-circulation of all the four dengue virus serotypes (1-4) and concurrent infection of 2 & 3, 1 & 3, and 1 & 4 serotypes was found. Predominant clinical features of the patients were fever (100%), headache (39%), vomiting (9.8%) and joint pain (4.16%). Haemorrhagic manifestation was recorded in one patient who subsequently died. Entomological surveys revealed profuse breeding of Aedes mosquitoes in all the affected municipal wards with high HI (37.5-71.43%), CI (53.84-86.95%) and BI (80-208.33%). Presence of IgM antibody, co-circulation of all the serotypes and concurrent infection with more than one serotype in the same individual confirmed the outbreak due to dengue virus infection. Preventive and control measures undertaken following the epidemiological investigation helped in controlling the outbreak.