Abstract
BackgroundVertical transmission is one of the transmission routes for Babesia microti, the causative agent of the zoonotic disease, babesiosis. Congenital Babesia invasions have been recorded in laboratory mice, dogs and humans. The aim of our study was to determine if vertical transmission of B. microti occurs in naturally-infected reservoir hosts of the genus Microtus.MethodsWe sampled 124 common voles, Microtus arvalis; 76 root voles, M. oeconomus and 17 field voles, M. agrestis. In total, 113 embryos were isolated from 20 pregnant females. Another 11 pregnant females were kept in the animal house at the field station in Urwitałt until they had given birth and weaned their pups (n = 62). Blood smears and/or PCR targeting the 550 bp 18S rRNA gene fragment were used for the detection of B. microti. Selected PCR products, including isolates from females/dams and their embryos/pups, were sequenced.ResultsPositive PCR reactions were obtained for 41% (89/217) of the wild-caught voles. The highest prevalence of B. microti was recorded in M. arvalis (56/124; 45.2%), then in M. oeconomus (30/76; 39.5%) and the lowest in M. agrestis (3/17; 17.7%). Babesia microti DNA was detected in 61.4% (27/44) of pregnant females. Vertical transmission was confirmed in 81% (61/75) of the embryos recovered from Babesia-positive wild-caught pregnant females. The DNA of B. microti was detected in the hearts, lungs and livers of embryos from 98% of M. arvalis, 46% of M. oeconomus and 0% of M. agrestis embryos from Babesia-positive females. Of the pups born in captivity, 90% were born to Babesia-positive dams. Babesia microti DNA was detected in 70% (35/50) of M. arvalis and 83% (5/6) of M. oeconomus pups. Congenitally acquired infections had no impact on the survival of pups over a 3-week period post partum. Among 97 B. microti sequences, two genotypes were found. The IRU1 genotype (Jena-like) was dominant in wild-caught voles (49/53; 92%), pregnant females (9/11; 82%) and dams (3/5; 60%). The IRU2 genotype (Munich-like) was dominant among B. microti positive embryos (20/27; 74%) and pups (12/17; 71%).ConclusionA high rate of vertical transmission of the two main rodent genotypes of B. microti was confirmed in two species of naturally infected voles, M. arvalis and M. oeconomus.
Highlights
Vertical transmission is one of the transmission routes for Babesia microti, the causative agent of the zoonotic disease, babesiosis
A similar phenomenon has been recognized in a rodent community near Omsk, Russia [14], where 30–60% of Myodes and Microtus spp. voles were found to be infected with B. microti but no B. microti infection was detected in ticks collected from rodents and from the environment [14]
The highest prevalence of B. microti was detected in M. arvalis and the lowest in M. agrestis
Summary
Vertical transmission is one of the transmission routes for Babesia microti, the causative agent of the zoonotic disease, babesiosis. Voles of the genus Microtus constitute the main natural hosts of the protozoan parasite Babesia microti [1, 2]. Babesia microti is an important zoonotic parasite, responsible for the great majority of human cases of babesiosis reported in the USA [5, 6]. Ticks of the genus Ixodes are the main vectors of Babesia parasites, with the common tick, Ixodes ricinus, being the main vector in Europe [10,11,12]. Microtus spp. generally show high prevalence of B. microti despite low infestation by I. ricinus instars and low prevalence of B. microti in this tick species. We hypothesized that the high prevalence of B. microti in Microtus spp. in our area is maintained by alternative routes of transmission, the most likely of which is vertical transmission from female voles to their offspring
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
