00000000A double peak haemorrhagic fever epidemic occurred in India for the first time in Calcutta between July 1963 and March 1964(16). DEN-2 virus strains were isolated from patients with severe haemorrhagic manifestations during the frist peak and chikungunya viruses were isolated during the second peak. No severe haemorrhagic manifestation or shock case was reponted among the patients with chikungunya infections. Further outbreaks occurred in 1965, 1967 and 1968. All four serotypes of dengue virus have been isolated from various parts of India(17-19). Outbreak of fever of unknown aetiology suspected to be DHF have been reported annually, with the affected number ranging from 1000 to 5000 and with a case fatality rate of about 0.5 per cent.

00000000In New Delhi, outbreaks of dengue fever were reported in 1967, 1970 and 1982(19). DEN-2 was isolated during the 1967 outbreak and DEN-1 and DEN-3 were isolated during the 1970 epidemic. An explosive outbreak of dengue fever occurred between August and October 1982. Sera were collected from 36 patients, from which 18 strains of DEN-1 and two strains of DEN-2 were recovered. This report confirmed the endemicity of dengue virus infection in New Delhi. It was noteworthy that no haemorrhagic manifestations or fatalities were recorded.

Number of Reported cases and deaths of Dengue and DHF in India 1991-1996