Prevalence of ovine and caprine oestrosis in Ambo, Ethiopia.

A study was carried out to estimate the prevalence, larval burden and risk factors of ovine and caprine oestrosis from December 2007 to May 2008 on 554 heads of randomly selected sheep and goat slaughtered at Ambo town, Western Shoa, Ethiopia. The results show an overall prevalence of 59.9% with infection rate of 69.8% and 47.3% in sheep and goats respectively. No statistically significant difference in the prevalence was noted with regard to the assumed risk factors like sex, nose color, face color, horned versus polled, origin, and months (p > 0.05). Sheep were nearly twice more likely to be infected as compared to goats (p = 0.0001, odds ratio (OR) = 1.975). Age of the animals was found to be protective (OR = 0.579; 95% confidence interval = 0.393, 0.853; p = 0.006). As compared to very fat animals, poor (p = 0.040, OR = 4.834), medium (p = 0.049, OR = 4.198), and fat (p = 0.022, OR = 5.795) body condition animals are more likely to be infected by Oestrus ovis larvae. Nasal and sinus cavity pathology is positively correlated with the total larval count (r = 0.56, p < 0.0001). Out of a total of 3,770 larvae collected, 57.5% were L1, 30.8% L2, and 11.7% L3 larvae. All the three larval instars were seen throughout the study months. It is concluded that oestrosis is a common problem in the study area and more prevalent in sheep than goats, in adult than young, and in animals with poor body condition.