Theileria parva causes an economically devastating tick-borne disease called East Coast fever (ECF), which affects
cattle in central, eastern and southern Africa. Determination of seasonal infection rates for T. parva is crucial for
epidemiological understanding and for strengthening ECF management practices. However, this information is
lacking for most pastoralist areas with high livestock density, such as the Monduli District in the Maasai steppe,
northern Tanzania. A cross-sectional study was carried out to estimate the prevalence of T. parva in wet and dry
seasons, and to assess understanding of management practices associated with T. parva amongst pastoralists’
cattle. A total of 960 cattle owned by 130 pastoralists were randomly selected from ten study villages in each
season and blood samples analysed for T. parva prevalence using a nested polymerase chain reaction (PCR).
Seroprevalence for T. parva in the wet season was assessed using an enzyme-linked-immunosorbent assay
(ELISA). Information on relevant management practices was gathered using a standardized questionnaire.
Multivariable logistic regression was used to evaluate the association between T. parva parasitaemia and animal,
farm and village-level factors. The prevalence of T. parva parasitaemia was 15.9% (95% CI = 0.13–0.19) and
31.6% (95% CI = 0.28–0.36) in wet and dry seasons, respectively. All cattle were sero-positive. T. parva
parasitaemia was significantly associated with age of the animal, sampling season, and study village. All 130
cattle owners interviewed (100%) reported that they could easily recognise ECF and the vast majority (97.7%)
identified swollen lymph nodes as the most prominent sign. At least 70% reported to understand the involvement
of R. appendiculatus in ECF transmission. The use of both commercial drugs and herbal medicines for ECF
treatment was reported by 54.6% of cattle owners. Among commercial drugs reported, the most commonly used
was alamycin 300 mg/ml (oxytetracycline dehydrates). Tick control by hand spraying was reported by the
majority (90.8%) of cattle owners and less than half (45.4%) reported to vaccinate their cattle. This research
provides evidence of widespread T. parva infection across Monduli District, and baseline information on seasonal
occurrence. This information can assist the planning of more appropriate control strategies in pastoralist communities
both now and into the future as predicted climatic changes progress in the region and potentially
influence ECF occurrence and transmission.