Retrospective study of Oestrus ovis larvae infestation in small ruminants in Grenada, West Indies

Oestrosis is a nasal cavity myiasis caused by Oestrus ovis larvae from Oetrus ovis diptera flies in small ruminants. The presence of the larvae in the nasal cavity is known to cause rhinitis and sinusitis which can negatively impact the productivity of small ruminants. The aim of the present study was to estimate the prevalence of Oestrus ovis larvae infestation in sheep and goats presented for necropsy. We reviewed necropsy records of sheep and goats submitted to the Veterinary Pathology diagnostic laboratory at St. George's University from 2001 to 2017. Out of 104 goat necropsy cases, Oestrus ovis larvae were observed in 8 goats giving a prevalence of 7.7% (95% confidence interval (CI):3.38% to 14.6%). Similarly, from the 47 sheep necropsies, Oestus ovis larvae were observed in 4 sheep (8.5%) (95% CI: 2.83% to 20.46%). There was no significant difference in Oestrus ovis larvae infestation rates between sheep and goats (p = 1.000, Fisher's exact test). Oestrosis was an incidental finding in all the small ruminants examined at necropsy. This is the first report on Oestrus ovis larvae infestation in small ruminants in Grenada.