Keeping vectors in control

KOCHI: Among vector-borne diseases, Malaria and lymphatic filariasis are the two main villains accounting for the highest mortality rate across the world. More than half the world’s population, including India’s, is at risk of at least one of these diseases. Strengthening vector control, improved surveillance and better coordination at community levels are essential to curb this. Experts also recommend strengthening Integrated Vector Management (IVM).

“Our primary strategic goal is to support the Centre in eliminating vector-borne diseases (VBDs) and expanding integrated vector-borne disease surveillance. We are also working with relevant government departments to accelerate Lymphatic Filariasis (LF) elimination through the nationwide roll-out of triple-drug therapy (IDA – ivermectin, diethylcarbamazine, and albendazole). Screening and surveillance are key to preventing the reintroduction of lymphatic filariasis infection in large urban areas, which provide ideal breeding sites for the vectors,” said Dr Helen Jamet, deputy director (Vector Control, Malaria), Bill and Melinda Gates Foundation. 

Community-level coordination is one of the key elements in tackling the menace of mosquitoes and their breeding. “We need to go back to basics — education and awareness about vector-borne diseases in communities that suffer due to them, urban planning to provide better drainage and water supply systems, removing garbage, proper sanitation and improved housing facilities can prevent vector breeding.

Agricultural approaches such as intermittent irrigation are useful too. We need more people trained to catch and analyse vectors so that we know what diseases are being transmitted and where,” said Dr Helen.Interventions including insecticidal bed nets, preventing stagnation, clearing debris from blocked gutters, cleaning vases and covering water storage containers can remove the breeding spots of mosquitoes that carry the viruses to an extent.

“We are concerned about epidemics like diseases including dengue, malaria, chikungunya, seasonal influenza, leptospirosis prevalent in particular geographic regions during monsoon and post-monsoon,” said Dr Helen.

The author, N K Ganguly, is a former Director-General of the Indian Council of Medical Research

What is IVM?
IVM is an approach by the World Health Organisation that encourages optimal use of resources for efficient, cost-effective, and sustainable vector control. This approach has been adopted by the National Vector Borne Disease Control Programme (NVBDCP) in India, a country where the occurrence of multiple overlapping vector-borne diseases provides a strong rationale for an integrated approach.

What can be done?
When the Zika virus outbreak happened, a major drive for creating a vaccine was launched. Zika virus is not new, it is a 45-year-old infection. But when cases peaked in Brazil and other countries, vaccination efforts were found to be economically non-viable. So, as of now, the major thrust will be towards vector control, surveillance in pregnant women and newborns. The vector management tools can be strengthened with the participation of the communities and the government.

Why should Kerala worry?
Kerala introduced the Aedes Albopictus mosquito. They are a very hardy vector that thrives in rubber plantations and date palm handis. Surveillance in pregnant women for Zika virus should be mandated. Measuring the head circumference of newborns is necessary to monitor anencephaly, where the foetus develops without a major part of the brain and skull during Zika infection.

Is Zika replacing dengue?
No. One of the very important things to note is that dengue and Zika were co-existing in Brazil. In India, there was a cross-immunity already existing in the population, thereby preventing an explosion of Zika virus transmission. But the claim has no scientific proof.