Vida Irani (Biology) and collaborators have published an interdisciplinary study on the tick-borne pathogens of Pennsylvania small mammal hosts titled ““Higher Prevalence of Babesia microti than Borrelia burgdorferi in small mammal species in central Pennsylvania, USA” in the peer-reviewed journal Vector-Borne and Zoonotic Diseases.
Working with colleagues from the University of Pittsburgh Medical Center and the Western Pennsylvania Conservancy, Irani and biology student Kevin Regan, along with biology faculty Jeffery Larkin and Paul Nealen, assessed the relative distributions of tick-borne, human disease-causing pathogens among six small mammal host species common in Central and Western Pennsylvania forests.
In concert with other published studies, Irani’s group noted a high prevalence of the bacterium Borrelia burgdorferi (the causative agent of human and animal Lyme disease) in their samples. Their study was the first to also assess the prevalence of the protozoan Babesia microti (the cause of the human disease babesiosis) in these same small mammal hosts, demonstrating that B. microti is in fact more common in these host species than is B. burgdorferi.
B. microti shares the same tick vector, primary host reservoir, and route of transmission as that of B. burgdorferi, and B. microti is comparatively more common in its host species than B. burgdorferi. Nonetheless, human Lyme disease is diagnosed much more frequently than is human babesiosis. These data suggest that either B. microti is less effectively transmitted to humans than is B. burgdorferi, or that B. microti is more effectively countered by our immune defenses.
An alternative hypothesis, supported by (i) the mixed symptoms which characterize babesiosis, and (ii) the relatively rare efforts made to diagnose it, is that babesiosis may be under-recognized in humans. Regardless, it is now clear that the causative agent of babesiosis is present at high levels in Pennsylvania wild mammal hosts of known tick vectors, a finding that suggests greater vigilance against and diagnostic efforts for babesiosis would be warranted.
Department of Biology