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.
CONCLUSION : 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.
