|Knowles, Donald - Don|
Submitted to: American Journal of Tropical Medicine and Hygiene
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/8/2005
Publication Date: 11/10/2005
Citation: Holman, P.J., Spencer, A., Telford, S.R., Goethert, H.K., Allen, A., Knowles Jr, D.P., Goff, W.L. 2005. Comparative infectivity of babesia divergens and a zoonotic babesia divergens-like parasite in cattle. American Journal of Tropical Medicine and Hygiene. 73(5):865-870. Interpretive Summary: Babesia divergens is a tick-borne blood parasite commonly found in cattle in southern Europe. It has also been shown capable of infecting humans, and is thus of concern to the human and veterinary medicine community. A parasite isolated from rabbits in the northeastern United States had several characteristics similar to B. divergens, and this study was designed to determine if it was capable of infecting cattle. The results suggest that despite the resemblance to B. divergens, this parasite is a different species. It failed to infect cattle, even animals that were immune compromised.
Technical Abstract: Babesia divergens-like parasites identified in human babesiosis cases in Missouri and Kentucky and in eastern cottontail rabbits (Sylvilagus floridanus) on Nantucket Island, Massachusetts share identical small subunit ribosomal RNA gene sequences. This sequence is 99.8% identical to that of Babesia divergens, suggesting that the U.S. parasite may be B. divergens, a causative agent of human and bovine babesiosis in Europe. Holstein-Friesian calves were inoculated with cultured Nantucket Island Babesia sp. (NR831) and B. divergens parasites and monitored by clinical signs, Giemsa-stained blood films, PCR, and culture. The NR831 recipients did not exhibit signs of infection and remained negative for all assays. The B. divergens recipients developed clinical infections and became positive by all assays. NR831 recipients were fully susceptible upon challenge inoculation with B. divergens. This study confirms that the Nantucket Island Babesia sp. Is not conspecific with B. divergens based on host specificity for cattle.