Host distribution and pathogen infection of fleas (Siphonaptera) recovered from small mammals in Pennsylvania

Authors: FEDELE, KAILA - Pennsylvania State University; POH, KAREN - Pennsylvania State University; BROWN, JESSICA - Pennsylvania State University; JONES, AMANDA - Walter Reed Army Institute; DURDEN, LANCE - Georgia Southern University; TIFFIN, HANNAH - Pennsylvania State University; PAGAC, ALEXANDRA - Pennsylvania State University; Li, Andrew; MACHTINGER, ERIKA - Pennsylvania State University

Submitted to: Journal of Vector Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/5/2020
Publication Date: 6/4/2020
Citation: Fedele, K., Poh, K.C., Brown, J.E., Jones, A., Durden, L.A., Tiffin, H.S., Pagac, A., Li, A.Y., Machtinger, E.T. 2020. Host distribution and pathogen infection of fleas (Siphonaptera) recovered from small mammals in Pennsylvania. Journal of Vector Ecology. 45(1):32-44.

Interpretive Summary: Ectoparasites such as ticks and fleas can spread various pathogens among host animal populations in nature. Like ticks, fleas can play an important role in transmission of various pathogens affecting humans and domestic animals. While multiple pathogens may be transmitted by fleas to humans, only plague is a nationally reportable disease in the U.S. Rodent species are known to serve as reservoir hosts for tick-borne pathogens in North America. Fleas, along with ticks, are commonly recovered from small mammals and their roles in the transmission of various tick-borne pathogens associated with rodents are not well understood. To address this knowledge gap, USDA ARS scientists joined force with researchers at Penn State University and two other institutions to investigate pathogens in fleas removed from rodents (the white-footed mouse and Southern red-backed voles) at their natural habitats in central Pennsylvania. Pathogen test results indicate the presence of two tick-borne pathogens Babesia microti and a Rickettsia felis-like bacterium in a flea removed from a white-footed mouse. This is the first report of B. microti DNA detected from a flea and the first report of a R. felis-like bacterium from rodent fleas in eastern North America. The results obtained from this study are of interest to flea and tick biologists, vector-borne disease epidemiologists, and researchers who work in the field of vector control and integrated pest management.

Technical Abstract: The number of flea-borne illnesses has increased over the past decade. However, the true number of cases related to all flea-borne pathogens remains unknown. To better understand the enzootic cycle of flea-borne pathogens, small mammals were trapped, and fleas were sampled in two state game lands in central Pennsylvania. A total of 541 small mammals were trapped, with white-footed mice (Peromyscus leucopus) and Southern red-backed voles (Myodes gapperi) accounting for over 94% of the captures. Only P. leucopus were positive for examined blood-borne pathogens, with 47 (18.1%) and ten (4.8%) positive for tick-borne pathogens Anaplasma phagocytophilum and Babesia microti, respectively. In addition, these two small mammals were the primary hosts for 61 fleas that were collected and tested for pathogenic bacteria. Orchopeas leucopus was the most common flea, contributing nearly 82% of the total number of fleas. Bartonella vinsonii subspecies aurpensis was detected in 19 fleas (16 in O. leucopus and three in Ctenophthalamus pseudagyrtes). Babesia microti and a Rickettsia felis-like bacterium were each detected in one O. leucopus flea sample. To the best of our knowledge, this is the first report of B. microti DNA detected from a flea and the first report of a R. felis-like bacterium from rodent fleas in eastern North America. Both species of rodents were collected in edge habitat characterized as transitional ecotonal areas. However, the distribution of pathogens followed the habitat preferences for each species, with P. leucopus found primarily in edge habitats and M. gapperi in wooded forests. This study provides evidence of emerging pathogens found in fleas, but further investigation is required to resolve the ecology of flea-borne disease transmission cycles.