Prevalence of Babesia bigemina and Anaplasma marginale infections and their associated risk factors among calves in Narok County, Kenya

Abstract

Babesiosis and anaplasmosis are major constraints to livestock production in many developing countries including Kenya. Therefore, their epidemiological data needs to be constantly updated. The current study was aimed at estimating the seroprevalence of Babesia bigemina and Anaplasma marginale and determine their associated risk factors among calves aged 3–12 months in Narok County, Kenya. A cross-sectional study was undertaken in Narok County, Kenya, between February and May 2023. A total of 402 calves from 76 farms were randomly selected from 8 villages in Sub-Counties of Naroosura Majimoto and Ololulunga. Data on individual calf and individual farm factors was collected via closed-ended questionnaires administered to someone who was involved the calves’ management. Blood was collected from the calves and processed for microscopy (smears) and serology (indirect ELISA using monoclonal antibodies), respectively. Descriptive analysis was performed for both categorical and continuous variables. Mixed effect logistic regression analysis was used to determine the association between seropositivity of the various risk factors with the random effect being the farm. The overall estimation seropositivity of B. bigemina, A. marginale and mixed infections of B. bigemina and A. marginale was 60%, 60% and 38.1% respectively. The overall prevalence on microscopy for B. bigemina, A. marginale and mixed infections of B. bigemina and A. marginale was 22.9%, 32.6% and 11.4%, respectively. Factors significantly associated with the seropositivity of the infections were increase in age (OR=2.736 for A. marginale, 3.030 for B. bigemina and 2.073 for A. marginale/B. bigemina), calves that receive acaricide treatment (OR=0.445 for A. marginale and 0.536 for A. marginale/B. bigemina) and infection history on the farm (OR=3.803 for A. marginale/B. bigemina). In conclusion, the seroprevalence of B. bigemina and A. marginale was relatively high. Control and prevention efforts should be enforced to reduce the risk of clinical diseases from the hemoparasites.