Geographic distribution of non-clinical Theileria parva infection among indigenous cattle populations in contrasting agro-ecological zones of Uganda: implications for control strategies

Abstract

BackgroundNon-clinical Theileria parva infection among indigenous cattle occurs upon recovery from primary disease during the first year of life. Continuous exposure to infection through contaminated tick infestations with absence of clinical disease gives rise to endemic stability. Endemic stable populations may become sources of infection if contaminated tick vectors are shared with susceptible exotic cattle. This study aimed at establishing a nationwide distribution of non-clinical T. parva infection among indigenous cattle populations to inform novel control strategies.MethodsThe occurrence of non-clinical T. parva infection among apparently healthy 925 indigenous cattle from 209 herds spread out in 10 agro-ecological zones (AEZs) was determined using a nested PCR assay. The influence of AEZ, breed, sex, age and farmers’ ranking of ECF importance were interrogated for influence of non-clinical parasite occurrence.ResultsThe overall prevalence of non-clinical T. parva infection was 30% (278/925). A gradual increase of non-clinical T. parva infection was observed ranging from 17% (95% CI: 0.03 – 0.23) to 43% (95% CI: 0.3 – 0.55) in the North Eastern Savannah Grasslands (NESG) to the Western Highland Ranges (WHR) respectively. A similarly associated 18% (95% CI: 0.07 – 0.28) and 35% (95% CI: 0.3 – 0.39) non-clinical parasite prevalence was observed among the East African shorthorn Zebu (EASZ) and Ankole cattle respectively. Average herd level non-clinical T. parva prevalence was 28%, ranging from zero to 100%. The likelihood of non-clinical T. parva infection was 35.5% greater in the western highlands compared to the northeastern semi-arid AEZs.ConclusionsNon-clinical T. parva occurs countrywide, structured along patterns of AEZ and breed gradients. These findings may guide policy formulation, deployment of integrated control strategies and local cattle improvement programs.

Spatial distribution of Brucella antibodies with reference to indigenous cattle populations among contrasting agro-ecological zones of Uganda

“…The study area has been described in Kabi et al (2014). Briefly, Uganda's total size is approximately 241,550.7 square kilometres (sq km), lies across the equator in Eastern Africa between longitudes 29.5 • East and 35 • East and between latitudes 4.5 • North and 0.5 • South.…”

“…The sample collection plan followed a landscape sampling strategy covering the 10 AEZs (Kabi et al, 2014). Samples and data for this study were collected from January 2011 to April 2012.…”

“…The sampled cattle were categorised into 7-24, 25-36, 37-72, 73-192 months old age groups. Means (obtained using Wald statistics taking into account the clustering of animals by herds) of brucellosis seroprevalences among the different AEZs, breeds, sexes, age (Adopted from Kabi et al, 2014) groups were computed at 95% confidence interval (CI). A generalized estimating equation (GEE) population-averaged univariable and multivariable logistic regression models with herd as a group variable and an exchangeable working correlation structure was engaged to estimate the odds ratios (OR) with robust intervals (95% CI) and corresponding p-values for variations within AEZs, breeds, gender and age groups.…”

Combining landscape genomics and ecological modelling to investigate local adaptation of indigenous Ugandan cattle to East Coast fever

“…Indeed, African taurine cattle might have reached eastern Africa sometime between ~8,000 and 1,500 YBP [7,8], and the most ancient zebuine colonization wave is estimated to have occurred between ~4,000-2,000 YBP from the Asian continent, as suggested by the first certain archaeological record dated 1,750 YBP [6]. Once T. parva spread to domestic populations, coevolution between the parasite and the new hosts likely led to the divergence between buffalo- ( T. parva lawracei ) and cattle-specific ( T. parva parva ) parasite strains [9,10], and to the appearance of infection-tolerant indigenous herds [11,12].…”

“…Specific regions in the South-West [14] and in the East [17] of current Uganda are reported to be ECF-endemically stable, thus making this country a candidate for investigating local adaptation to ECF. Moreover, indigenous Ugandan cattle populations are proven to be connected by high rates of gene flow [22], and a strong spatially varying selection is expected on their genomes because of regional climatic differences shaping ECF epidemiology over the country [11]. These requirements are all likely to have promoted local adaptation to the disease [23], even over short time scales (i.e.…”