Seroprevalence of Oestrus ovis infection in sheep in Southwest of Iran

Oestrus ovis, sheep nasal bot fly, is one of the important parasites and causes of sinus and nasal myiasis in small ruminants. It is a zoonotic infection that causes disturbing myiasis in humans. This study aimed to determine the seroprevalence of O.ovis infection in the sheep population in the southwest of Iran. During 2009-2010, blood samples were collected monthly and randomly from 1800 sheep (>6 months of age) of Ilam and slaughtered sheep of Ahvaz (the capital of Khuzestan). All sera were examined for antibodies to crude somatic antigens of O.ovis second-stage larvae using an Elisa test. Positive sera were prepared by marking the sheep, blood taking and direct observation of the parasite in the head. The somatic antigens were prepared by ultra-sonication of the second-stage larvae. Results of the ELISA test on the sheep sera revealed that seroprevalence of Oestrus ovis infection in sheep of Ilam and Khuzestan was 427 (47.4%), out of 900 and 398 (44.2%) out of 900 respectively. Mean seroprevalence of Oestrus ovis infection in sheep in south West-Iran was 825 of 1800(45.8%). Seasonal differences in the prevalence of the infection were significant (p<0.001), with the highest rates in spring (Apr.-May. 62.7%) and autumn (Oct. 61.5%, Nov. 76.0%), the lowest rates in summer (Aug. 27.1%-29.3%) and winter (Jan. 41.1%, Feb. 26.7%). The results of this study demonstrate that O.ovis has a widespread distribution in the sheep population of southwest-Iran. Control measures must be applied continuously to decrease the incidence of the infection in livestock herds.