Seroprevalence of Mycobacterium avium SSP paratuberculosis infection in Ethiopian dairy farms

Abstract

This study aimed to determine the seroprevalence of antibodies for Mycobacterium avium subspecies paratuberculosis (MAP) in dairy cattle in the Jimma zone of Ethiopia in 2011. A random sample of 29 herds was selected, and all mature cattle within these herds had a blood sample taken. Serum was tested in duplicate, as recommended by the manufacturer, for evidence of infection with MAP, using an antibody ELISA. A questionnaire was used to collect information from the owner or farm manager on cow and herd demographics and management to allow for comparisons of our results with other studies. Herd sizes ranged from 3 to 17 cows per herd, with 95% of cows being Holstein crosses, ranging in age from 3 to 15 years old (mean of 5.5 years). Milk production ranged from 1 to 20 kg/cow/day, with an average of 8.4 kg/cow/day. All farms used tie-stalls for their cows, 59% of farms allowed newborn calves to suckle their dams on the day of calving, and 54% of farms purchased cattle in the last 5 years. Of the 242 cattle tested, 5 cows (2.1% with a 95% confidence interval – 95%CI - of 0.2% to 3.9%) were seropositive. Due to the low test sensitivity, the true animal prevalence estimate was calculated to be 2.6% (95%CI: 0.6% to 4.6%). At least one animal tested positive in 3 of the 29 herds (10.3% - 95%CI: 0% to 21.7%). Adjusting for the low test sensitivity, the true herd prevalence estimate was calculated to be 32.6 % (95%CI: 15.2% to 50.0%). This study provides the first immunological evidence of the prevalence of exposure of Ethiopian cattle to MAP, and at levels similar to other countries with small-scale dairy production. Corroboration of these prevalences with pathological, microbiological, and/or immunological MAP research in Ethiopia is
warranted.

Keywords: Dairy Cattle, Johne’s, Paratuberculosis, Seroprevalence, Western Ethiopia