Interview I Dengue cases rising as municipal bodies wake up to containment measures too late: Ashwini Kumar of ICMR Vector Control Research Centre

Bio-medical scientist Dr Ashwini Kumar has been heading the Vector Control Research Centre under the Indian Council of Medical Research for the last three years. Under his leadership, the institute, apart from carrying out quality research on various vector-borne diseases, is also establishing an International Centre of Excellence for Training in Medical Entomology (the study of insects). This centre is aimed at enhancing the scope of training in public health entomology for in-service and fresh candidates by offering academic courses. In a chat with Moneycontrol, he spoke about how India can prepare better to fight vector-borne ailments such as dengue. Edited excerpts:

Among vector-borne diseases, dengue has emerged as a major public health challenge. Can you please elaborate what exactly your institute is doing about it?

We are investigating the outbreaks, wherever they happen. We are also serotyping to assess which type of serotypes are in circulation (dengue is caused by four types of viruses, which are spread by the female aedes egypti mosquito). We also try to isolate viruses from vectors and characterise those viruses from the vectors themselves. As far as dengue containment is concerned, as the dengue vector breeds in small containers, community outreach, community cooperation or participation is very important in controlling it. But unfortunately, it being a seasonal disease, is forgotten very soon, and there are innumerable breeding sites. Also, we understand that it is humanly impossible to clear all the breeding sites always.

As far as containment measures are concerned, we have been working on a Wolbachia (a type of bacteria) strategy as a potential dengue vector control strategy for the last few years. Trials related to this strategy are also happening in 11 other countries. Under this, Wolbachia-infected aedes aegypti mosquitoes (which carry the dengue and Chikungunya viruses) are used to control dengue as these mosquitoes are far less likely to spread the dengue virus (it is difficult for viruses to replicate inside the Wolbachia infected mosquitoes). Our studies so far have shown positive results but are yet to be approved by the department of biotechnology’s Review Committee on Genetic Manipulation before we can start field trials.

There are four dengue virus serotypes we know about. But are there some clear trends on which types are in circulation and whether they are capable of causing a spike in cases or severe cases?

These serotypes keep on shifting, changing. But it may not be the function of serotypes that causes cases to increase; it could be due to transmission, led by vector potential (due to increasing breeding and numbers), that this disease is actually spreading. Dengue so far had been limited to urban or peri-urban areas but now it is reaching rural parts as well.

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The responsibility of providing primary health services lies with primary health centres in rural areas and mostly municipal bodies in urban areas and seasons are very discrete. If you ask me, containing dengue-virus carrying mosquitoes is not that difficult; but what is happening is that municipal bodies start operating only when cases start going up.

However, what we should do is actually work in the lean season, because in the lean season the vector lies low. You should know where the mosquitoes are breeding and eliminate them. There is a saying in the army that you hit the enemy in the bunkers.

Are you saying there is a lack of efficiency at the municipal level that is leading to spurt in dengue cases across the country?

I would rather say that there is a manpower shortage. For vector control, specialists are required who understand what vectors are and where they are breeding and when to control them. We need more public health entomologists. When we know the seasons, we know the containment measures, and we can function efficiently. All municipal bodies should have entomologists.

Do we have enough entomologists in the country?

I do not have the numbers, but I can tell you that only Tamil Nadu has an appreciable number of entomologists. Andhra Pradesh and Karnataka have some but most other states have negligible numbers of these specialists.

We are also working in that direction. We have been offering an MSc in public health entomology for the last few years and the seats are now being raised from 8 to 20. Four other institutes under ICMR are also going to start this course and the number of degrees on offer will considerably go up.

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Apart from dengue, in which other vector-borne diseases is research happening?

Apart from dengue, a lot is happening to develop policies for lymphatic filariasis. We are also working to control it. Then we work on malaria in Koraput (Odisha) in the tribal heartland and some other districts. We work on leishmaniasis in Kerala, on Japanese encephalitis in Madurai. We also work on chikungunya, both in Kerala and elsewhere — wherever there are outbreaks — and advise the local government. We have also started research work on scrub typhus in a big way. We are actually developing diagnostics for scrub typhus because it can potentially kill in some cases, if not treated promptly.