Babesia microti is an emerging human pathogen in New York state and the causal agent of babesiosis, a malaria-like illness. B. microti is transmitted via tick vectors, and multiple vertebrate species may act as reservoirs. However, it is unclear whether different vertebrate species are equivalent in terms of infection prevalence and pathogen transmission to tick vectors. Our overall goal is to estimate the relative importance of each major host species in producing ticks infected with B. microti. Engorged larval ticks were collected from 10 mammal and 4 bird species captured and held in the summer of 2009 (total number of individuals = 105 birds, 160 mammals), and allowed to molt. These newly molted nymphs, which have a higher risk of transmitting pathogens to humans than other tick life stages, were tested for infection with B. microti.

Results/Conclusions

We developed a real-time PCR protocol that amplifies a 188 base pair fragment of 18S ribosomal DNA from B. microti. We demonstrate that the primers we designed have a low affinity for tick DNA at an annealing temperature of 64 degrees C. We were successfully able to amplify B. microti DNA from multiple animal hosts, including Peromyscus leucopus (white-footed mouse), which is also an important reservoir host for Borrelia burgdorferi, the causal agent of Lyme disease. We explore the relative sensitivity and specificity of this method and discuss its potential benefits and drawbacks in understanding the dynamics of B. microti. The data estimating infection prevalence and reservoir competence of each host species will be used to predict the number of infected nymphal ticks each host produces and will aid in management strategies to reduce risk of human exposure.