Of the over 3,000 mosquito varieties in the world, only 300 are the biting variety. They are area-specific and can be controlled if their breeding practices are attacked.
In the last seven to eight years the dengue has become a major factor for mortality and morbidity across the country. The Indian Council of Medical Research attributed the outbreak of Chikungunya in the State in 2006 to intrusion of forest species of the vector.
Until then, only Aedes aegypti, the dengue causing mosquito, was known for its virulent attacks. But the new species Aedes albopictus began raising its ugly head, says former director of public health S. Elango. Though it is believed that Aedes albopictus had surfaced from the Western Ghats, it has made its home in large swathes of western, central and northern regions of the State.
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“Vector density is measured in 10 man hours. How many mosquitoes a man can catch in an hour and that is multiplied by 10 to arrive at the measure. Entomologists use this technique to measure mosquito density. The measure holds good for vectors that transmit diseases like malaria, filariasis and chikungunya but not for dengue,” Dr. Elango adds.
In the case of dengue, when the mosquito bites a man, the virus persists in the mosquito and is transmitted to its progeny too. Since the flying range for Aedes aegypti is only 300 to 500m, the transmission is highly localised.