Detection of Oestrus ovis and associated risk factors in sheep from the central region of Yucatan, Mexico

A cross-sectional epidemiologic study was conducted in order to detect the presence of and to estimate the seroprevalence of Oestrus ovis L. infection in flocks of sheep from the central region of the state of Yucatan, Mexico . The risk factors associated with disease were also identified. A sample s ize of 10 animals per farm was used to detect seropositive animals, conside ring a 30% prevalence and 95% confidence level. Blood samples of 689 sheep from 88 flocks were collected and a questionnaire with questions about the flock and the host was applied. The thin layer immune assay test was used. The risk factors were screened using logistic regression procedures. 77% of the flocks had at least one-positive animal with antibodies against O. ovi s. The overall seroprevalence and standard error was 30.6 +/- 3.5%. Only fl ock size and sheep nose color showed association (P < 0.05) with the diseas e. The odds ratios for hocks with less than 11 and with 11 to 25 sheep, as related to herds with 25 or more sheep, were 0.74 and 1.73, respectively. S heep with dark noses had a higher risk (OR = 1.46) compared with sheep havi ng light noses (P < 0.05). (C)2000 Elsevier Science B.V. All rights reserve d.