Haemaphysalis longicornis (Acari: Ixodidae) failed to acquire and consequently transmit Babesia bigemina to naive cattle

Authors: Poh, Karen; Aguilar, Mitzi; CAPELLI-PEIXOTO, JANAINA - Washington State University; EVANS, JESSE - Washington State University; Chung, Chungwon; Ueti, Massaro

Submitted to: Ticks and Tick Borne Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/12/2026
Publication Date: 5/15/2026
Citation: Poh, K.C., Aguilar, M., Capelli-Peixoto, J., Evans, J.R., Chung, C.J., Ueti, M.W. 2026. Haemaphysalis longicornis (Acari: Ixodidae) failed to acquire and consequently transmit Babesia bigemina to naive cattle. Ticks and Tick Borne Diseases. 17(3). Article 102659. https://doi.org/10.1016/j.ttbdis.2026.102659.
DOI: https://doi.org/10.1016/j.ttbdis.2026.102659

Interpretive Summary: Asian longhorned ticks (Haemaphysalis longirocnis) are spreading rapidly in the United States, raising concern that they might transmit Babesia bigemina, an agent of bovine babesiosis. This study tested whether these ticks could acquire, maintain, or transmit the parasite, using the cattle fever tick (Rhipicephalus microplus) as a control experiment. We examined transmission through eggs, across molting stages, and from nymphs to adults. After feeding ticks on infected calves in acquisition, only adult tick midguts and not adult ovaries nor nymphs had small amounts of parasite DNA detected. To test transmission, presumably infected ticks from acquisition fed on naive calves. Calves remained health and tested negative for B. bigemina during the observation period. In addition, ticks remained negative throughout the tested life stages. The findings indicate that Asian longhorned ticks are not competent vectors for B. bigemina, reducing concern that this invasive species will spread bovine babesiosis in the United States should it be reintroduced.

Technical Abstract: Since its introduction into the United States, the Asian longhorned tick (Haemaphysalis longicornis) has spread to at least 21 states and represents a growing threat to livestock due to its broad host range and rapid reproductive capability. Given its ability to transmit livestock pathogens such as Theileria orientalis Ikeda, it is a high priority to determine the vector competence of a United States population of H. longicornis for other livestock pathogens that circulate or may re-emerge domestically, such as the causative agent of bovine babesiosis, Babesia bigemina. This study evaluated the vector competence of H. longicornis for the acquisition and transmission of B. bigemina, using the Rhipicephalus microplus system as a positive control. Transovarial transmission, transstadial maintenance across all life stages, and transstadial transmission from nymphs to adults of B. bigemina in H. longicornis were assessed as potential transmission routes. Acquisition nymphs and adult females fed to repletion and after 12 days post-repletion, a subset of nymphs were frozen, and adult females were dissected (ovaries and midguts). Tick tissues or whole ticks were tested for the presence of B. bigemina using nested PCR (nPCR) followed by quantitative PCR (qPCR). Only female midguts had any detectable level of B. bigemina DNA after acquisition. During transmission, all subsequent life stages and progeny did not transmit B. bigemina to naïve calves, as evidenced by negative nPCR and follow-up qPCR results and the absence of bovine babesiosis signs in calves. These results suggest that H. longicornis is not a vector for B. bigemina.