On August 21st, Matthew Rogers and colleagues published an article in PLoS Pathogens which shows that the parasite Leishmania tricks host immune defense cells into feeding it rather than killing it. This development may help in the search for an effective vaccine against leishmaniasis, a painful, disfiguring, potentially fatal disease that afflicts approximately 12 million people worldwide.
Using a mouse model, Rogers et al demonstrated that the parasite secretes a gel-like substance within the sand-flies that are primary transmitters of the disease. This gel must be regurgitated in order for the fly to bite and feed on its target, allowing the gel, along with the parasites, to enter the target’s skin. This gel actually attracts the macrophages (white blood cells) meant to eat and digest invading pathogens. That these cells then feed the parasites rather than destroy them allows the Leishmania parasite to establish an infection with little resistance.