The prevalence of <i>Trypanosoma</i> species in cattle in Calabar Metropolis of Cross River State in Southern Nigeria

Abstract

This study was conducted to determine the prevalence of Trypanosoma species in cattle due to the increasing movement of animals within the metropolis. Blood specimens were collected from 1200 cattle during slaughter at four abattoirs (Bogobiri, Nasarawa, Ibesikpo, and Ikot Eneobong) between February and May 2022. Dry universal containers were positioned in the stream of blood oozing from the cut neck of each cow. From these containers, 4 mL of blood was aspirated into an ethylenediamine- tetra-acetic acid (EDTA) bottle using a 5 mL syringe. Blood specimens were processed for microscopy at the Parasitology Laboratory of the University of Calabar Teaching Hospital. Wet preparation of each specimen was performed and examined for motile haemoparasites. Triple centrifugation was performed on 2 mL of each blood specimen at increasing speeds of 1000, 1500, and 3000 revolutions per minute for 5 min. During each centrifugation process, the resulting plasma was harvested and re-centrifuged. Finally, the resulting buffy coat layer and deposit were resuspended and used to prepare smears on clean microscope slides. After drying in air, blood smears were stained with 3% Giemsa solution for 30 min. The microscopy results showed that 570 stained blood specimens were positive for Trypanosoma species, which morphologically resembled Trypanosoma brucei because of their long free flagellum. The overall prevalence of trypanosomes in cattle was 47.5%. Of the total number of infected cattle, 330 were males and 240 were females. The
prevalence rates in male and female cattle were 27.5% and 20 %. There was no statistical difference in the occurrence of trypanosomes in the male and female cattle (X² = 9.41; p > 0.05). However, the findings suggest that male cattle tend to forage more into the bush and are thus more likely to be exposed to bites of infected Glossina flies than their female counterparts. The high prevalence of trypanosomes in cattle, as shown in this study, may have major epidemiologic significance, considering the increasing rate of open grazing by cattle within residential areas in major cities all over Nigeria.