Ability of the Vector Tick Boophilus microplus To Acquire and Transmit Babesia equi following Feeding on Chronically Infected Horses with Low-Level Parasitemia

Abstract

The protozoan parasite Babesia equi replicates within erythrocytes. During the acute phase of infection, B. equi can reach high levels of parasitemia, resulting in a hemolytic crisis. Horses that recover from the acute phase of the disease remain chronically infected. Subsequent transmission is dependent upon the ability of vector ticks to acquire B. equi and, following development and replication, establishment of B. equi in the salivary glands. Although restriction of the movement of chronically infected horses with B. equi is based on the presumption that ticks can acquire and transmit the parasite at low levels of long-term infection, parasitemia levels during the chronic phase of infection have never been quantified, nor has transmission been demonstrated. To address these epidemiologically significant questions, we established long-term B. equi infections (>1 year), measured parasitemia levels over time, and tested whether nymphal Boophilus microplus ticks could acquire and, after molting to the adult stage, transmit B. equi to naive horses. B. equi levels during the chronic phase of infection ranged from

Prevalence of equine Piroplasmosis and its association with tick infestation in the State of São Paulo, Brazil

“…microplus was susceptible to infection by T. equi and was able to transmit it to horses. This finding was later confirmed by other workers (STILLER et al, 2002;UETI et al, 2005;2008). Cattle are the primary host for R.…”

“…Studies have shown that three major tick species infest horses in Brazil: Dermacentor nitens (= Anocentor nitens), Amblyomma cajennense, and Rhipicephalus (Boophilus) microplus (FALCE, 1986;BARBOSA et al, 1995;HEUCHERT et al, 1999;LABRUNA et al, 2001;COSTA PEREIRA et al, 2005 (GUIMARÃES et al, 1998;STILLER et al, 2002;UETI et al, 2005;2008). In fact, T. equi-infected horses have been reported in areas where R.…”

Infestação experimental de equinos por Rhipicephalus (Boophilus) microplus

“…Hoje, no Brasil, a importância de R. microplus ultrapassa os interesses da pecuária bovina e recai também sobre a criação equina, sobremaneira, pela transmissão de T. equi (UETI et al, 2005), um hemoparasita que afeta o desempenho de equinos, seja de trabalho ou esporte, bem como causa restrições no comércio internacional de equinos infectados (FRIEDHOFF et al, 1990).…”

Acquisition and transmission of Theileria parva by vector tick, Rhipicephalus appendiculatus

“…T. parva is acquired by immature ticks during blood feeding, and transmission of T. parva is strictly trans-stadial as the parasite is transmitted only by the nymphal and adult stages after acquiring infections during feeding as larvae or nymphs, respectively. In tick-borne hemoprotozoan parasite infections, the level of parasitemia in the reservoir hosts at the time of tick feeding is critical for efficient acquisition of the pathogens by the ticks (Eriks et al, 1993;Ueti et al, 2005). Interestingly, Ueti et al (2005) have demonstrated the ability of the vector tick Boophilus microplus to acquire and transmit Babesia equi following feeding on chronically infected horses with low-level parasitemia.…”

“…In tick-borne hemoprotozoan parasite infections, the level of parasitemia in the reservoir hosts at the time of tick feeding is critical for efficient acquisition of the pathogens by the ticks (Eriks et al, 1993;Ueti et al, 2005). Interestingly, Ueti et al (2005) have demonstrated the ability of the vector tick Boophilus microplus to acquire and transmit Babesia equi following feeding on chronically infected horses with low-level parasitemia. Ticks (7.1-50%) that acquired B. equi from chronically infected horses, 4 as well as those (22%) fed during the acute phase of infection, successfully transmitted the parasite to naive horses.…”