title: Geographic distribution of non-clinical Theileria parva infection among indigenous cattle populations in contrasting agro-ecological zones of Uganda: implications for control strategies.
abstract: BACKGROUND
  Non-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.
  
  
  METHODS
  The 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.
  
  
  RESULTS
  The 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.
  
  
  CONCLUSIONS
  Non-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.
authors.affiliation: Department of Environmental Management, Molecular Genetics Laboratory, College of Agricultural and Environmental Sciences, Makerere University, P,O, Box 7062/7298 Kampala, Uganda. freddykabi@gmail.com.
authors.forename: Fredrick
authors.initials: F
authors.lastname: Kabi
authors.forename: Charles
authors.initials: C
authors.lastname: Masembe
authors.forename: Vincent
authors.initials: V
authors.lastname: Muwanika
authors.forename: Halid
authors.initials: H
authors.lastname: Kirunda
authors.forename: Riccardo
authors.initials: R
authors.lastname: Negrini
mesh_terms: D000383:Agriculture; D000818:Animals; D002417:Cattle; D017753:Ecosystem; D005260:Female; D008297:Male; D015995:Prevalence; D016797:Theileria parva; D013801:Theileriasis / Q000453:epidemiology / Q000469:parasitology*; D014454:Uganda / Q000453:epidemiology