Abstract:
Haemoparasitic infections represent major constraints to livestock productivity and welfare in
tropical regions, causing anemia, immunosuppression, and reduced performance in affected
animals. These vector-borne pathogens, primarily transmitted by ticks, include species of
Theileria, Babesia, and Anaplasma, which collectively threaten bovine well-being and rural
livelihoods. In Sri Lanka, such infections are widespread, particularly in the dry zones, where
high tick abundance facilitates pathogen transmission. The Kilinochchi district in the northern
province, characterized by its tropical dry climate and predominantly extensive and semiintensive
cattle management systems, provides a highly favorable environment for the spread of
tick-borne haemoprotozoa such as Theileria orientalis. The present study, conducted from May
to October 2025, aimed to determine the prevalence of T. orientalis in cattle from two
veterinary ranges, Karachchi and Kandawalai, within the Kilinochchi district. We randomly
collected 160 samples from 50 farms across both veterinary ranges. The farms were selected
based on previous reports of infection and their management practices to ensure representative
sampling. of the 160 samples, indigenous cattle included 35 from Karachchi and 39 from
Kandawala, while crossbred cattle included 45 from Karachchi and 41 from Kandawala. This
distribution allows a valid comparison of prevalence between breeds and locations that were
examined microscopically, with Theileria piroplasms observed in 49 samples, corresponding to
an overall microscopy prevalence of 30.6%. These 49 smear-positive samples were
subsequently subjected to species-specific PCR targeting the major piroplasm surface protein
(MPSP) gene of T. orientalis using primers TO-MPSP-F (5′-CTTTGCCTAGGATACTTCT-3′)
and TO-MPSP-R (5′-ACGGCCAAGTGGTGAGAACT-3′) resulting in the confirmation of 19
PCR-positive samples. PCR confirmed T. orientalis infection in 40% of samples from
Karachchi and 37.5% from Kandawalai. The chi-square results show that there was no
significant difference in infection rates between the two veterinary ranges or between the
different breeds. The very low χ² value for ranges (0.06) means that infections were almost the
same in both locations. For breeds, the χ² value (≈2.14) was also not high enough to show a real
difference. This means that under the current farm conditions, neither the location nor the breed
had a clear effect on the occurrence of infection. This study confirms the molecular presence of
T. orientalis in Kilinochchi, underscoring its subclinical circulation and the need for integrated
diagnostics, effective tick control, and improved herd management strategies.
