New Delhi: In a bid to control vector-borne diseases in the national capital, Indian Council of Medical Research (ICMR), the country’s apex medical research body, is mapping dengue and chikungunya prone zones in Delhi. Once the mapping using the geospatial data is completed, the researchers are planning to use an innovative passive mosquito control method by placing insecticides at the identified mosquito breeding sites.

The National Institute of Malaria Research (NIMR), under ICMR, is working on this project with the National Centre for Scientific Research and Institut Pasteur, France, and will soon start using the technique called as “autodissemination of pyriproxyfen ((PPF) -pyridine-based pesticide)".

“The use of PPF for Aedes aegypti (mosquito that spreads dengue and chikungunya) control focuses on a strategy to exploit the innate behaviour of mosquitoes. This approach, called auto-dissemination, is based on the assumption that mosquitoes exposed to a PPF-contaminated surface are able to spread this chemical to their own breeding sites," said Olivier Telle, senior visiting researcher and urban health geographer at the National Centre for Scientific Research.

The strategy, scientists say, is particularly effective in the case of Aedes aegypti because the mosquito breed distributes its eggs among a number of breeding sites. Most of all, the strategy is a passive control, since once stations are implemented, they can last more than two weeks. This means that the female mosquito is itself disseminating the PPF to its own breeding site.

“It is a great idea since all the aedes breeding site are very difficult to find. The technique is inexpensive as well. Unlike fumigation, this will help to control vector without important human resources. We are using this method in Madeira (Portugal), and it showed very promising results," said Telle.

Control of vector born diseases is among the key issues discussed at the 70th session of the Regional Committee of World Health Organisation (WHO), currently being held in Maldives. The South-East Asia Region bears a high burden of vector-borne diseases, including dengue, malaria and lymphatic filariasis which can be attributed to environmental changes and movement of people from one place to another.

“In recent years the transmission dynamics and risk of vector-borne diseases have shifted due to unplanned urbanization, increased movement of people and goods, and environmental changes," Dr Poonam Khetrapal Singh, regional director, WHO South-East Asia Region, said.

“Countries need to establish and strengthen effective entomological surveillance systems to study local mosquito species, their susceptibility to insecticides, monitor insecticide resistance, as well as vector and human behaviours that may allow mosquitoes to avoid interventions and thereby maintain disease transmission. Information made available through such enhanced and improved surveillance is critical to planning and implementing tailored and effective strategies," she said.

On similar lines, the scientists in Delhi are using the geospatial data for gathering information like environmental factors such as temperature and infrastructure and mobility of individuals that will help in disease prediction and control.

“Dengue cannot be eliminated from Delhi due to various reasons, we can only control it. In our research we have observed that we had not only a changing geography on three years data, but the relation with environment kept changing, depending on the complex interplay of factors. However, it is important to understand the mobility of Delhi’s population to better evaluate how and where the disease will be diffused, since contamination can occur everywhere, from work to recreational places," said Telle.

“The next step would be to implement innovative tools to control dengue mosquito. It is indeed a big task to control mosquito everywhere in Delhi, but we can locate the areas where vector control would have the maximum benefit for all," he said.

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