Diagnostic accuraccy of ehrlichia ruminantium test for heartwater screening in Masvingo district

Abstract

Background We evaluated the diagnostic accuracy of the Ehrlichia Ruminantium test (Post Mortem vs Direct Brain Smear) to screen for Heartwater in Masvingo District. Methods Between July 2016 and July 2017, cattle and goat carcasses were screened for heartwater (tick abundance, characteristic post mortem lesions and direct brain smear for microscopy). Sensitivity and specificity and predictive values of E Ruminantium were calculated using microscopy results as our gold standard. Epi info software version 7 was used. Findings 145 animal carcasses were selected, 101 were positive by post mortem examinations and 44 were negative by post mortem examinations. Samples had to underdo tentative diagnosis by direct brain smear in the lab. Among all the participants, sensitivity was found to be 88% and 82% respectively. Sensitivity and specificity was calculated seperately for cattle and goats, for cattle sensitivity and specificity was 91% and 70.3% respectively for goats sensitivity and specificity was 82% and 72.2% respectively. Conclusion The diagnostic tests used have adequate sensitivity for heartwater screening in this population.