A small, stinging fly that carries an important parasitic disease, visceral leishmaniasis, often lays its eggs on dogs before infecting humans. However, the insect manages to modify the smell of dogs to make them irresistible to female flies.
Visceral leishmaniasis (or black fever) causes between 20 and 30,000 deaths per year . It is the deadliest parasitic disease in the world after the indomitable malaria. A parasite of the genus Leishmania is the cause of the disease and the insect vector is a small stinging fly of the Phlebotominae family . As in the case of mosquitoes, only females are dangerous. And if left untreated, visceral leishmaniasis is fatal in almost all cases.
Common in Europe, the disease is also raging on the American continent with 95% of infections. Among the most affected countries, Brazil is in the lead. The insect manages to lay eggs on its human hosts via another animal reservoir, namely dogs. As explained in a study by the University of Lancaster (UK) published in PLOS Pathogens, they manage to modify the smell man's best friend to attract female flies.
Prior to this work, researchers knew that this "parasitic manipulation" could occur on rodents. By changing their smell, the latter became more attractive to female flies. This resulted in more bites and thus, better transmission of the parasite. On the other hand, the fact that dogs are also one of the natural reservoirs of the disease in humans is a real discovery. Remember in passing that infected dogs transmit the disease by biting and licking.
As part of their work, the researchers collected hair and blood from dogs in Governador Valadares (Brazil). Then, after screening the animals, they extracted the fragrant chemicals about fifteen dogs. These substances were then presented to male and female sandflies. Hairs attracted insects of both sexes, but infected samples attracted 67.7% of females , a data absent in males.
Now, scientists want to answer other questions. They wonder, for example, why the smell of infected dogs attracts female flies so much and would like to identify the most irresistible chemicals. They would also like to know which receptors activate in insects. According to the researchers, this information could prove important in the fight against visceral leishmaniasis.
