title: Heterogeneity in the prevalence and intensity of bovine trypanosomiasis in the districts of Amuru and Nwoya, Northern Uganda.
abstract: BACKGROUND
  Livestock trypanosomiasis, transmitted mainly by tsetse flies of the genus Glossina is a major constraint to livestock health and productivity in the sub-Saharan Africa. Knowledge of the prevalence and intensity of trypanosomiasis is important in understanding the epidemiology of the disease. The objectives of this study were to (a) assess the prevalence and intensity of trypanosome infections in cattle, and (b) to investigate the reasons for the heterogeneity of the disease in the tsetse infested districts of Amuru and Nwoya, northern Uganda.
  
  
  METHODS
  A cross-sectional study was conducted from September, 2011 to January, 2012. Blood samples were collected from 816 cattle following jugular vein puncture, and screened for trypanosomes by HCT and ITS-PCR. A Pearson chi-squared test and logistic regression analyses were performed to determine the association between location, age, sex, and prevalence of trypanosome infections.
  
  
  RESULTS
  Out of the 816 blood samples examined, 178 (22 %) and 338 (41 %) tested positive for trypanosomiasis by HCT and ITS-PCR, respectively. Trypanosoma vivax infection accounted for 77 % of infections detected by ITS-PCR, T. congolense (16 %), T. brucei s.l (4 %) and mixed (T. vivax/ T. congolense/T.brucei) infections (3 %). The risk of trypanosome infection was significantly associated with cattle age (χ (2)   = 220.4, df = 3, P < 0.001). The highest proportions of infected animals were adult males (26.7 %) and the least infected were the less than one year old calves (2.0 %). In addition, the risk of trypanosome infection was significantly associated with sex (χ (2)  = 16.64, df = 1, P < 0.001), and males had a significantly higher prevalence of infections (26.8 %) than females (14.6 %).
  
  
  CONCLUSIONS
  Our results indicate that the prevalence and intensity of trypanosome infections are highly heterogeneous being associated with cattle age, location and sex.
authors.affiliation: Department of Biology, Faculty of Science, Gulu University, P.O. Box 166, Gulu, Uganda. angwechh@yahoo.com.
authors.forename: Harriet
authors.initials: H
authors.lastname: Angwech
authors.affiliation: Department of Biology, Faculty of Science, Gulu University, P.O. Box 166, Gulu, Uganda. jpenmogi@yahoo.com.
authors.forename: Jack H P
authors.initials: JH
authors.lastname: Nyeko
authors.affiliation: Department of Biology, Faculty of Science, Gulu University, P.O. Box 166, Gulu, Uganda. auma1opiyo@gmail.com.
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Opiyo
authors.affiliation: Department of Biology, Faculty of Science, Gulu University, P.O. Box 166, Gulu, Uganda.
authors.forename: Joseph
authors.initials: J
authors.lastname: Okello-Onen
authors.affiliation: Department of Biology, Faculty of Science, Gulu University, P.O. Box 166, Gulu, Uganda. opiro@yahoo.co.uk.
authors.forename: Robert
authors.initials: R
authors.lastname: Opiro
authors.affiliation: Department of Biology, Faculty of Science, Gulu University, P.O. Box 166, Gulu, Uganda. richard_echodu@yahoo.co.uk.
authors.forename: Richard
authors.initials: R
authors.lastname: Echodu
authors.affiliation: Department of Biology, Faculty of Science, Gulu University, P.O. Box 166, Gulu, Uganda. malingageoffrey@yahoo.com.|Department of Biology, University of Eastern Finland, P. O. Box 111, 80101, Joensuu, Finland. malingageoffrey@yahoo.com.
authors.forename: Geoffrey M
authors.initials: GM
authors.lastname: Malinga
authors.affiliation: Biosciences Eastern and Central Africa (BecA), International Livestock Research Institute (ILRI) - Hub, Old Naivasha Road, P.O. Box 30709- 00100, Nairobi, Kenya. m.njahira@cgiar.org.
authors.forename: Moses N
authors.initials: MN
authors.lastname: Njahira
authors.affiliation: Biosciences Eastern and Central Africa (BecA), International Livestock Research Institute (ILRI) - Hub, Old Naivasha Road, P.O. Box 30709- 00100, Nairobi, Kenya. r.skilton@cgiar.org.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Skilton
mesh_terms: D000367:Age Factors; D000818:Animals; D002417:Cattle / Q000469:parasitology; D003430:Cross-Sectional Studies; D005260:Female; D008297:Male; D015995:Prevalence; D012307:Risk Factors; D012720:Severity of Illness Index; D012737:Sex Factors; D014346:Trypanosoma brucei brucei; D014348:Trypanosoma congolense; D016689:Trypanosoma vivax; D014353:Trypanosomiasis, African / Q000453:epidemiology / Q000469:parasitology / Q000662:veterinary; D014354:Trypanosomiasis, Bovine / Q000453:epidemiology* / Q000469:parasitology; D014454:Uganda / Q000453:epidemiology