OVINE LENTIVIRAL INFECTION (MAEDI-VISNA) IN MOROCCO - A SEROLOGIC ANDPOSTMORTEM SURVEY

In an attempt to estimate the importance of maedi/visna virus infectio n in Moroccan sheep and to assess the relationship, if any, between se roreactivity and pulmonary lesions, an abattoir-based serologic survey was undertaken over a period of 2 years. A total of 1000 blood sample s and related lungs were collected from sheep of different breeds and ages slaughtered at three major municipal abattoirs in Morocco (Casabl anca, Kenitra and Rabat). The agar gel immunodiffusion test showed tha t the seropositivity for all samples was 24.8%. At post-mortem examina tion, 107 out of the 248 (43.1%) sheep scored seropositive had gross l esions of maedi; typical microscopic lesions were observed in 125 (50. 4%) seropositive sheep, including the 107 with gross lesions. Of the 7 52 seronegative animals, only 13 (1.7%) sheep had macroscopic maedi-li ke lesions. Seventeen (2.2%) of these seronegative cases, including th ose with gross lesions, had histologic pulmonary changes consistent wi th maedi. No other maedi/visna-associated lesions were found during th is study; however, coexisting secondary bacterial bronchopneumonia was frequently encountered. The association between serologic and patholo gic findings is reported and discussed.