Retrospective analysis of laboratory diagnostic data to assess the prevalence and seasonal variation of Ehrlichia ruminantium in commercial farms of Lephalale Municipality, Limpopo, South Africa

Abstract

Heartwater is an economically important disease of livestock and some wild ruminants in Southern Africa. The study used retrospective laboratory data from Lephalale Veterinary Laboratory, Limpopo to establish the prevalence and seasonal occurrence of heartwater in commercial farms of Lephalale Municipality between 2010 and 2022. A total of 472 brain samples from livestock (cattle, goats, sheep) and game carcasses brought to the laboratory for postmortem examination were subjected to heartwater testing using Giemsa staining technique. The overall prevalence of heartwater in Lephalale Municipality was 34.1% (95% CI = 29.9-38.6, p < 0.001). During the years under investigation, there was a significant (p < 0.001) variation, with the highest and lowest prevalence in 2022 (72.2%) and 2019 (6.3%), respectively. The prevalence of heartwater was high in springbok (57.1%), sheep (49.3%), cattle (36.6%) and goats (32.2%). Heartwater was detected throughout the year with autumn having the highest (40.6%) frequency followed by summer (40.3%), spring (30.5%) and winter (25.5%). This study is the first to establish the prevalence and seasonality of heartwater in Lephalale Municipality which will serve as a baseline for prevention and control strategies as well as future epidemiological studies. Official surveillance programmes, more research on the distribution and genotypes of E. ruminantium in the area need to be undertaken for better understanding of the disease in the area.

Keywords: A. hebraeum; E. ruminantium; Heartwater; Lephalale Municipality; Livestock; Wild animals.