Study design and sample collection
The study design and sampling collection are described in detail elsewhere (Falzon et al., 2019). Briefly, four LMs and neighbouring SHs were selected in each county (Figure 1), where each LM was closely associated with a cattle or pig SH. At each LM, 10 animals (six cattle, three goats, and one sheep) were selected via systematic random sampling. We attempted to select six cattle, three goats, and one sheep during each visit, though the number of animals sampled did not always follow the above ratio as it was occasionally challenging to get consent from owners of small ruminants. Signed consent was sought from the animal owners or traders accompanying sampled animals, and a short questionnaire was administered to capture demographic and animal ownership details. Animals were then physically restrained and, after a general clinical examination, blood was drawn by a qualified veterinarian from the jugular vein using a vacutainer. Nasal swabs and faecal samples were also collected. Any external parasites present on the hide of the selected animals were removed with gloved hands and placed into falcon tubes containing 70% ethanol. At cattle and pig SHs, a similar procedure was followed. In addition to ticks, lice and fleas were collected if present on sampled animals. Sample bottles and blood tubes were barcoded and transported to the field lab in Busia in a cool box with ice packs. Arthropods were stored at -40°C at the International Livestock Research Institute (ILRI) Department of Veterinary Services lab in Busia before being shipped on dry ice to the Martin Lüscher Emerging Infectious Diseases (ML-EID) laboratory at the International Centre of Insect Physiology and Ecology (icipe) where they were stored at -80°C.