Dengue in Gujarat state, India during 1988 & 1989.

Following the reports of epidemics of febrile illness from several rural and urban areas of Gujarat state (India) in 1988, epidemiological investigations were carried out and dengue (DEN) virus activity was demonstrated in large cities such as Surat and Rajkot as well as several villages in Sabarkantha district. Two strains of dengue type-2 each were isolated from human sera from Surat city and a village in Sabarkantha district. Six strains of dengue virus were isolated from Aedes aegypti mosquitoes collected at Chotasan village, two of which were confirmed as DEN type-2. Of the 560 patients' sera tested from different areas (including villages and townships), 122 showed evidence of dengue infection and another 236 showed a broader reaction with flaviviruses. Entomological investigations showed a widespread distribution of Ae. aegypti both in urban and rural areas. In the household conditions this mosquito was found to breed predominantly in containers with non-potable water. Amongst these, cement containers manufactured in towns and distributed to the villages seem to play an important role in the spread of this species. In non-residential areas prolific breeding of Ae. aegypti was observed in automobile tyre dumps, and varied types of scrap, in towns and villages. Distribution and relative prevalence of the species were studied in 46 towns and villages, covering the spectrum of rural-urban-continuum. These studies provide an indication regarding the mechanism of the spread of DEN virus through peoples' movement, transport, the process of urbanisation etc.

Monitoring Japanese encephalitis virus activity using domestic sentinel pigs in Mandya district, Karnataka state (India).

Domestic pigs were used as sentinels in Mandya district (Karnataka state) in India during 1984 to 1986 to monitor the activity of Japanese encephalitis (JE) virus in nature. Out of 213 sentinel pigs studied in 11 localities, 44 pigs placed at 5 localities showed seroconversion to Japanese encephalitis virus. A pig mosquito cycle, operating throughout the year appears to be one of the maintenance mechanisms of the virus in the study area in addition to the bird-mosquito cycle.

Post-epidemic serological survey for JE virus antibodies in south Arcot district (Tamil Nadu).

Following an extensive epidemic of Japanese encephalitis (JE) in 1981, a serological survey was carried out in the South Arcot district of Tamil Nadu in April 1982. Serum specimens were obtained from 10 villages with serologically proven infections and 6 villages with no reported case of encephalitis during the 1981 epidemic. The serum specimens tested for haemagglutination inhibition, complement fixing and neutralizing antibodies, showed a high prevalence of JE (49.17%), West Nile (40.78%) and dengue (18.14%) viruses with predominance of JE. The prevalence did not differ between the villages with or without Japanese encephalities. There was also no difference between the family members and neighbours.

Clinical & virological study of dengue fever outbreak in Jalore city, Rajasthan 1985.

An epidemic of acute febrile illness caused by dengue virus occurred in Jalore town, in south-west Rajasthan, in April and May, 1985. Most patients had classical signs and symptoms of dengue fever or had only a mild atypical febrile illness. A few patients had in addition haemorrhagic manifestations/shock or encephalitis. Virological studies (carried out by the National Institute of Virology, Pune) showed that dengue type 3 virus was the main etiological agent. This is the first reported outbreak of dengue in the arid zone in western Rajasthan, that occurred in summer (April-May) in contrast to other parts of India, where such outbreaks are commonly reported after the rains (between August and November).