Prevalence and seasonal variation of tick-borne haemoparasites in cattle from north-eastern Uganda.

Theileriosis, babesiosis, anaplasmosis, and ehrlichiosis are the most important constraints to livestock production in Karamoja region, North-eastern Uganda. However, there are no large-scale studies on the prevalence and seasonal variation of tick-borne haemoparasites that are needed to design and implement tick-borne disease control programs. We collected 7080 blood samples from cattle across four districts of north-eastern Uganda during the dry (November 2022 to February 2023) and wet (July to August 2023) seasons. These samples were screened for the most important tick-borne haemoparasites (TBH) by conventional PCR, followed by capillary sequencing of representative PCR amplicons. There was no statistically significant difference [p > 0.05] in the overall prevalence of infection with at least one of the screened TBHs during the wet [39.0%; CI 7.3-40.6] and dry seasons [39.2%: CI 37.6-40.9]. Prevalence of the individual TBHs during the dry season were:-Babesia bigemina 11.8% (CI 10.8-12.9), Babesia bovis 11.8% (CI 10.8-12.9), Anaplasma marginale 9.2% (CI 8.2-10.2), Ehrlichia ruminantium 5.1% (CI 4.4-5.8) and Theileria parva 1.3% (CI 1.0-1.8). Prevalence of individual TBHs during the dry season were:-T. parva 22.6% (CI 21.3-24), A. marginale 13.6% (CI 12.5-14.8), B. bigemina 12.7% (CI 11.6-13.8), E. ruminantium 1.4% (CI 1.1-1.9) and B. bovis 0.3% (CI 0.1-0.5). Geospatial location, increasing age, sex, overnight stay in cattle kraals, and cattle breeds were significant predictors of infection with different TBHs during either season. Co-infection with the individual TBHs ranged between 0.14-2.74% and 0-1.64% during the dry and wet seasons respectively. In both seasons, the co-infection rate with all five TBHs was 0.03% (CI 0.0-0.16). Phylogenetic analyses of the representative TBH sequences revealed high level of conservation within the targeted genes of the samples in this study and those within the East Africa region that were retrieved from the GenBank. This study demonstrate high level of infection/co-infection with different TBHs in both dry and wet seasons indicating that ticks and tick-borne diseases are a major impediment to livestock production in Karamoja region. This shows the need of having a ticks and tick-borne disease control program. Moreover, B. bovis was detected for the first time in this region.