A study led by Dr. Albert Picado, ISGlobal, published in PlosOne and funded by the Society of Tropical Medicine and Hygiene, describes an innovative method to measure the efficiency of different mosquito nets in preventing the passage of the Leishmania vector. The technique consists in using cows as bait, surround them by mosquito nets and, with the help of a light trap, count the number of sand flies that managed to go through the net. Unsurprisingly, they found that the most efficient nets were insecticide-treated nets with smaller hole sizes as compared to those used normally used in the region, or to untreated nets.
In malaria studies, one approach to measure the efficiency of mosquito nets is counting the number of mosquito bites in a person under the net. Volunteers in these studies have received prophylaxis to avoid contracting the disease. However, as Dr. Picado explains, this cannot be done with leishmaniasis since there is no available prophylaxis for the disease. "The method we describe here represents a quick and low-cost proof-of-concept approach to measure the efficacy of vector control measures in the field."
Leishmaniasis is considered a neglected infectious disease by the World Health Organisation (WHO). Although it has a global distribution (it is present in South America, Africa, Asia and Europe), it it is particularly prevalent among poor communities of developing countries since the major risk factors are poverty, malnutrition, population mobility and environmental changes. India, Nepal and Bangladesh alone represent 67% of the global burden of visceral leishmaniasis (or kala-azar), the most severe form of the disease. Despite the implementation of diverse control measures, leishmaniasis still represents a major public health threat and an obstacle to the socio-economical development in certain rural zones of the Indian subcontinent.
Perhaps the cow, a sacred animal for the Hindus, can now make its own contribution to the development of new control strategies for the disease.