Outbreak of febrile illness due to dengue virus type 3 in Calcutta during 1983.

An epidemic of dengue fever broke out in Calcutta between July and August 1983. Persons of all age groups were affected with a preponderance of young adults. Haemorrhagic manifestations and shock were not observed. Virus was isolated from 4 acute phase sera and identified as dengue type 3 (DEN-3), the first isolation of DEN-3 virus in Calcutta. Serotesting with 9 paired blood samples established dengue infection in 7 and a flavivirus group reaction in 2. Examination of 36 single sera revealed presumptive dengue infection in 15 and a flavivirus group reaction in 17, while the remaining 4 were negative to all flavivirus antigens.