title: Prevalence of pathogenic trypanosomes in anaemic cattle from trypanosomosis challenged areas of Itezhi-tezhi district in central Zambia.
abstract: BACKGROUND
  The measure of anaemia status using packed cell volume (PCV) can be a reliable indicator of African trypanosomosis (AT) in the absence of other anaemia-causing conditions. However, studies that have estimated prevalence of anaemia in cattle from AT endemic areas have rarely reported the prevalence of the disease in the anaemic cattle. Therefore we investigated the prevalence of AT in anaemic cattle at sites that had recently reported the disease in Itezhi tezhi district of central Zambia.
  
  
  METHODS
  During a survey, blood samples were collected from 564 randomly selected cattle for anaemia determination from seven crush pens (Mutenda, Kapulwe, Banachoongo, Itumbi, Iyanda, New Ngoma and Shinampamba). At a PCV- value cut off of 26 %, all samples positive for anaemia were subjected to both parasitological examination on thick and thin blood smears and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) for detection of trypanosome DNA. Fisher's exact test and a mixed effect logistic regression analyses were used to determine and measures associations, respectively.
  
  
  RESULTS
  Of 564 cattle screened, 58 (10.3 %; 95 % CI: 7.8-12.8 %) had anaemia. PCR-RFLP results showed that 17 (29.3 %; 95 % CI; 17.2-41.4 %) anaemic cattle were positive for pathogenic trypanosomes compared to 1 (1.7 %; 95 % CI: 0.0-5.2 %) on parasitological examination using thick smears. The infections were caused by Trypanosoma congolense and Trypanosoma vivax. Fisher's exact test showed a strong association between PCV and pathogenic trypanosome infection (P = 0.004). A mixed effect multivariate logistic regression showed that a one unit increase in PCV reduced the likelihood of detecting AT with PCR-RFLP by 24.7 % (95 % CI: 4.6-40.6 %; P = 0.019) in anaemic cattle, taking into account their age and sex, with random effects for crush pen.
  
  
  CONCLUSIONS
  These results suggest that T. congolense and T. vivax could be important causes of anaemia in cattle reared in AT endemic areas of Itezhi tezhi in Central Zambia. This also suggests that even though pathogenic trypanosomal infection was strongly associated with PCV, it could only account for up to 41 % of the anaemia in cattle. Therefore further investigation to ascertain other factors responsible for anaemia in AT endemic areas of Itezhi tezhi in Central Zambia is needed.
authors.affiliation: Department of Public Health, School of Medicine, University of Zambia, P.O. Box 50110, Lusaka, Zambia. njelembombewe@yahoo.com.|Tsetse and Trypanosomiasis Control Section, Department of Veterinary Services, P.O. Box 350001, Chilanga, Zambia. njelembombewe@yahoo.com.
authors.forename: Njelembo J
authors.initials: NJ
authors.lastname: Mbewe
authors.affiliation: Department of Paraclinical Studies, School of Veterinary Medicine, University of Zambia, P.O. Box 32379, Lusaka, Zambia. b.namangala@unza.zm.
authors.forename: Boniface
authors.initials: B
authors.lastname: Namangala
authors.affiliation: Department of Public Health, School of Medicine, University of Zambia, P.O. Box 50110, Lusaka, Zambia. lungowesitali@gmail.com.
authors.forename: Lungowe
authors.initials: L
authors.lastname: Sitali
authors.affiliation: Department of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort, 0110, South Africa. Ilse.Vorster@up.ac.za.
authors.forename: Ilse
authors.initials: I
authors.lastname: Vorster
authors.affiliation: Department of Public Health, School of Medicine, University of Zambia, P.O. Box 50110, Lusaka, Zambia. ccmichelo@yahoo.com.
authors.forename: Charles
authors.initials: C
authors.lastname: Michelo
mesh_terms: D000740:Anemia / Q000209:etiology / Q000662:veterinary*; D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000453:epidemiology* / Q000469:parasitology; D016054:DNA, Protozoan / Q000235:genetics; D008853:Microscopy; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D015995:Prevalence; D014348:Trypanosoma congolense / Q000145:classification / Q000302:isolation & purification*; D016689:Trypanosoma vivax / Q000145:classification / Q000302:isolation & purification*; D014353:Trypanosomiasis, African / Q000150:complications / Q000453:epidemiology / Q000469:parasitology / Q000662:veterinary*; D015024:Zambia / Q000453:epidemiology
chemical_list: D016054:DNA, Protozoan