Transovarial transmission efficiency of Babesia bovis by Rhipicephalus (boophilus) microplus
By Jeanne Marie Howell, D.V.M., Ph.D.
Washington State University
Chair: Donald P. Knowles
Babesia bovis is a deadly disease of cattle transmitted by Rhipicephalus (Boophilus)
ticks resulting in severe economic losses in vast regions of the world where it is endemic.
Infected cattle develop high fever, depression, anemia, and often die. Although essentially
eradicated from the U.S. in 1943, a quarantine zone remains along the U.S. border with
Mexico. The endemicity of babesiosis in Mexico, in combination with the development of
acaracide resistant Boophilus ticks, facilitates the reintroduction of this pathogen into the
U.S. The parasite is acquired by feeding adult female Boophilus ticks, and is transmitted
transovarially to developing larval offspring as the kinete stage. Infectious sporozoites
develop within larval salivary glands and are transmitted when larvae commence feeding
on susceptible cattle. The efficiency of female tick acquisition and transovarial
transmission of B. bovis is poorly understood. In order to address the risk imposed on U.S.
cattle, it is essential to examine the efficiency at which adult female Boophilus ticks acquire
blood stages of B. bovis and how efficiently the kinete stage is passed transovarially to
developing offspring. These studies were designed to first evaluate the efficiency of B.
bovis transmission following acquisition feeding on splenectomized acutely parasitemic
cattle, and secondly investigate the efficiency of transovarial transmission following
acquisition feeding on spleen intact persistently infected calves.
School:Washington State University
School Location:USA - Washington
Source Type:Master's Thesis
Keywords:boophilus microplus cattle tick
Date of Publication: