The Telegraph
Since 1st March, 1999
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Weapons are ready, users aren’t

New Delhi, Sept. 6: In his 30 years on the frontline of India’s war on mosquitoes, biologist Pradeep Das has sometimes found himself pitted against unhelpful public attitudes and, as he puts it, “ostrich-like” government officials.

Illness and death from dengue, Japanese encephalitis and malaria in India might have been lower, Das says, had people changed their behaviour and government agencies acted on research instead of displaying knee-jerk reactions after outbreaks.

More than 400 children have died from encephalitis in eastern Uttar Pradesh over the past three weeks and Bengal this week declared a dengue epidemic with 820 confirmed cases.

Das is among the researchers who are worried that science has taken a backseat in the nation’s efforts to prevent mosquito-borne epidemics.

“The scientific tools are available. But mosquito control also needs managerial skill and political will. We don’t have enough of either,” says Das, director of the Vector Control Research Centre (VCRC) in Pondicherry.

His colleagues have spent decades investigating the blood-guzzling behaviour of mosquitoes in the forests of eastern India, in urban concrete jungles and on farms where mosquitoes thrive in paddy fields and on pigs.

Solutions involving sanitation, mosquito nets, good farm and water management have, Das says, often remained ignored.

“Society mistakenly accepts outbreaks as natural calamities, whereas in reality, they are predictable and preventable,” says Dr T. Jacob John, the former head of virology at the Christian Medical College, Vellore.

Good surveillance, John says, could have helped predict the encephalitis outbreak in Gorakhpur. “For Japanese Encephalitis and malaria, you need to track build-up of mosquito density weeks in advance to see if it rises beyond a critical level.”

Blood tests on pigs, which carry the encephalitis virus, could have led to evasive action such as fogging in high-risk areas where pigs are found harbouring the virus.

At the Vector Control Research Centre, scientists have learnt to use software to predict outbreaks using data about mosquito biting habits, satellite images, rainfall patterns and the topography of the area under analysis.

But they are not invited to make routine predictions. At least once, a VCRC forecast was simply ignored.

Das cites the instance from years ago. A VCRC team had predicted that Bangalore city did not require insecticides that year because the ecological conditions were not ripe for malaria. “But they bought insecticides anyway,” Das says.

Scientists are also worried about the abuse of DDT to tackle mosquitoes.

The main malaria mosquito Anopheles culicifacies has turned resistant to DDT and malaria epidemics have dogged DDT-sprayed areas in Assam, Andhra Pradesh, Bihar, Gujarat, Madhya Pradesh, Orissa and Rajasthan.

The malaria control effort used 42,000 tonnes of DDT between 1997 and 2002 and expects to spray 66,000 tonnes between 2002 and 2007. Yet, annual malaria incidence since 1997 has hovered between 1.86 million and 3 million.

Last year, dengue outbreaks affected nearly 2,400 people in 10 states while encephalitis infected more than 1,500 children in six states, claiming 400 lives.

In the 1990s, the Malaria Research Centre had proposed what its former director Vinod Sharma calls “bioenvironmental control” of mosquitoes. It involved unleashing fish in water bodies to eat mosquito larvae, planting trees to suck excess water from the ground, and water and drain management.

“This approach has been too slow in taking off,” says Sharma, now a distinguished fellow at the Indian Institute of Technology, New Delhi. “Instead, malaria control continues to use DDT although it is ineffective against mosquitoes in India.”

Scientists also say the public appears oblivious to steps to prevent such infections.

Aedes aegypti, the tiger-striped mosquito that carries the dengue virus, breeds in tyres, water coolers, flower vases, even disposable cups. Any pool of water that has collected more than five days is a potential breeding ground.

Public health experts say people in cities need to train themselves to clean out accumulated water pools once a week. In paddy fields, people should segregate themselves from pigs. “Our job is to just empower people with knowledge ' it is up to them whether to use it or ignore it,” says Das.

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