Abstract
BackgroundThe 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.MethodsDuring 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.ResultsOf 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.ConclusionThese 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.
Highlights
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
The present study demonstrated that a larger proportion of anaemic cattle from AT challenged areas of Itezhi tezhi were not infected with pathogenic trypanosomes
The large proportion of anaemic cattle not being infected with AT implies that there is need to carry out investigations that will establish other anaemia causing factors in order to plan for effective interventions to improve animal health in AT endemic areas of Itezhi tezhi
Summary
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. African trypanosomosis (AT), known as nagana, is a disease of livestock caused by unicellular parasites called trypanosomes (Protozoa, Kinetoplastida). It is transmitted by tsetse flies (Glossina spp.) and other biting flies. Even though human settlement is not allowed in the National park, it is permitted in the GMA Man introduces his domestic livestock in the same physical environment that harbours tsetse flies and wildlife when he settles in GMAs. man introduces his domestic livestock in the same physical environment that harbours tsetse flies and wildlife when he settles in GMAs This situation has greatly contributed to the distribution and risk of AT in Southern Africa [10, 11]
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