Mosquitoes and the diseases they transmit have always been a major public health concern. The Directorate of Public Health and Preventive Medicine plans to map the area-specific prevalence of different breeds of mosquitoes to aid in taking up appropriate control measures.
K. Kolandaswamy, Director of Public Health, said the Department focuses on the disease-causing vector across the State.
“We continuously monitor breeding of Aedes mosquitoes that cause dengue and chikungunya, Culex mosquitoes that cause Japanese Encephalitis and female Anopheles that cause malaria,” he said.
The directorate has plans to collect mosquito samples from all areas to find out the species composition. “We want to find out which type of mosquitoes breeds where so that we can plan our activities and interventions accordingly. As of now, we take up such activity if any local body approaches us. We are planning to do this on a continuous basis so that we can have a system in place for area-specific measures.”
The directorate monitors the breeding of Aedes , which continues to pose a problem for Tamil Nadu, through larval index and house index. Breeding of Culex in agricultural fields is also monitored. “Though we have eliminated Filariasis , we continue to monitor mosquito positivity through night surveys,” he added.
Malaria restricted
The density of malaria-causing vector, female Anopheles , is also being monitored in certain areas, he said, adding: “We have managed to restrict malaria to five locations in the State — small pockets in Chennai, Hogenakkal in Dharmapuri, a few coastal villages in Kanniyakumari, Rameswaram and coastal areas of Thoothukudi. Similarly, we had 13 districts that were earlier endemic regions for Japanese Encephalitis. We have brought down the number of cases in these districts through vaccination.”
B. Dhanraj, former chief vector control officer, Chennai Corporation, said the incidence of malaria in Chennai was less since the breeding of female Anopheles had reduced. “The pattern of mosquito breeding can change every year. For instance, cases of dengue usually peak in October and start declining in November. But this year, cases peaked in November. The problem for the city is Culex mosquitoes now. With longer nights, the Culex- mosquito bites (night biters) is more. We need to understand climate to know the pattern,” he said.
