Bacteria coming to take the sting out of dengue

fter conventional methods like insecticides, fumigation and insecticide-treated nets proving ineffective in containing the dreaded Aedes Aegypti mosquitoes, which spread dengue, chikungunya and other viral infections, experts in India are looking closely at a bacteria to take on the menace from within.

The microbe that caught the researchers’ eye is the Wolbachia, a mostly benign microbe that has the ability to block the growth of viruses like the ones that spread dengue. It is the common bacterium found in as much 60 per cent of the insect family – except Aedes Aegypti. The effort therefore is to introduce a strain of the bacterium in Aedes that would control the virus – and the mosquito itself – from multiplying.

A Memorandum of Understanding was signed between Indian Council of Medical Research (ICMR) and Monas University, Australia, for the research, starting with dengue virus,” said ICMR director general Dr Soumya Swaminathan, also the secretary of union department of health research, on the sidelines of 13th conference on vectors and vector-borne diseases organised by the National Academy of Vector Borne Disease and Central University of Tamil Nadu, here on Monday.

“The bacterium will contain dengue, chikungunya, zika and other viruses spread by this mosquito. The Aedes mosquitoes will not carry the infection, so even if it bites humans, the virus will not spread. This will help to eliminate dengue, chikungunya and other viruses if proven successful,” explained Dr P Jambulingam, director, Vector Control Research Centre, Puducherry, ICMR.

The preliminary works for the research study, fully funded by ICMR, was ongoing at the research centre in Puducherry.

As the ‘wMel’ strain of Wolbachia that is effective in controlling the viruses is not present in India, researchers here are planning to import the strain from Monas University. The process for obtaining permission to import it was on. “Wolbachia bacteria will not survive outside the body. So we are importing the insect larvae, develop them into adults, and then allow the Wolbachia carrier mate with the mosquitoes here. We will develop colonies like this in Phase I of the research,” Dr Jambulingam said. “Then they will be released into the field and studied,” he said, adding the next phases would be taken up only after ensuring the success in the first step.

Using Wolbachia is not a new idea. After it was identified in the 1920s, research has been going on for years to understand more about the characteristic of the microbe that is inimical to the viruses that are harmful to humans. This has picked up pace after the recent zika scare.

The Aedes mosquitoes get viruses like dengue from infected humans. Once inside the insect, the virus replicates within 8-12 days, after which anyone bitten by it gets infected. Researchers have found that the bacterium technique works in two ways: once inside, Wolbachia spreads to all cells and stymies the growth of viruses. Even if these mosquitoes bite, the infection will not be passed. Also, while this bacteria is passed from mother to its offspring, when an infected male mates with an uninfected female, it will not let the eggs hatch. This means there is a possibility of controlling the Aedes population that does not have the bacteria.