Insecticide-releasing house paint found to be effective in killing yellow fever mosquitoes

New Delhi: An exterior house paint that releases small amounts of insecticide over a long time after coating houses was found to be effective in killing yellow fever mosquitoes in two African neighbourhoods in a new research. Researchers described the insecticidal paint as a "promising strategy" to prevent and control malaria at a household level, as it is effective against any type of vector disease transmitted by these mosquitoes, including dengue fever, chikungunya, zika fever, among others.

The researchers, led by those at Jean Piaget University of Cape Verde, Praia, Africa, also said that the paint was sustainable and eco-friendly and that it found acceptance among almost all of the population in the neighbourhoods where it was trialled.

"Here we show that VESTA insecticide paint is effective at killing Aedes aegypti, the yellow fever mosquito, in the city of Praia for at least one year," said Lara Ferrero Gomez, lead author of the study published in the journal Frontiers in Tropical Diseases.

For the study, trained volunteers painted 228 houses in two Praia neighborhoods particularly vulnerable to diseases transmitted by mosquitoes, which the researchers said was due to insufficient drainage, leading to floods during monsoons, and poor wastewater management.

Praia is the capital city of Cape Verde, an island nation off west Africa, where vector-borne disease have been prevalent for centuries. Residents in the island nation are also known to store water owing to insufficient and disrupted water supply, which is another one of the causes for the transmission of vector-borne diseases.

At one, three, six, and 12 months after painting, two houses in each neighbourhood were randomly selected for performing WHO cone bioassays, a key method outlined by the World Health Organisation to investigate the biological activity of a material's surface treated (or not) with active ingredient under controlled laboratory conditions.

"Bioassays record the mortality of A. aegypti mosquitoes after exposing them for half an hour to the insecticidal paint. This allows us to directly evaluate the effectiveness of the insecticidal paint," explained Ferrero Gomez.

All three insecticide paint formulations - VESTA, ARES and 5A IGR - were found to lead to complete mortality of A. aegypti mosquitoes one month after the houses were painted.

The researchers said that three months after painting, all formulations still exceeded the WHO efficiency threshold of 80 per cent.

While the VESTA formulation continued to meet WHO requirements at months six and 12, the other two formulations fell below the threshold at month six, they said.

"The paint works by releasing very small quantities of insecticide over a long period, which makes it more sustainable and eco-friendlier," said Ferrero Gomez.

No serious effects of the paint were observed on the residents' health, even as 10 per cent of them reported mild eye or nose irritation and 4 per cent reported headache.