More than one million people in tropical countries contract the parasite Leishmaniaevery year through the bites of infected sand flies. Most people develop disfiguring – but not life-threatening – skin lesions at the sites of the bites. But if the parasite spreads to the internal organs, it causes a disease known as visceral leishmaniasis, which kills about 30,000 people every year.
Stephen Beverley, the Marvin A. Brennecke Professor and head of the Department of Molecular Microbiology at Washington University School of Medicine in St. Louis, is a world expert on the deadly parasite. He was studying Leishmania’sbasic biology when he serendipitously rejuvenated the field of parasite virology. Along with longtime collaborator Nicolas Fasel of the University of Lausanne in Switzerland, and other colleagues, Beverley discovered that Leishmania parasites infected with a virus – dubbed Leishmaniavirus – cause significantly worse disease than those without a virus. Other researchers later showed that viruses in related parasites such as Trichomonas, which causes vaginal infections, and potentially Cryptosporidium, which causes diarrhea, also may exacerbate disease.
In a Q & A, Beverley talks about the nascent field of parasite virology and his newest paper, an evolutionary study that suggests Leishmania’s viruses may have helped it make the jump from infecting insects to infecting vertebrates.