Ovine Lentiviral Infection (Maedi/Visna) in Morocco: A Serologic and Postmortem Survey

Abstract

Summary In an attempt to estimate the importance of maedi/visna virus infection in Moroccan sheep and to assess the relationship, if any, between seroreactivity and pulmonary lesions, an abattoirbased serologic survey was undertaken over a period of 2 years. A total of 1000 blood samples and related lungs were collected from sheep of different breeds and ages slaughtered at three major municipal abattoirs in Morocco (Casablanca, Kénitra and Rabat). The agar gel immunodiffusion test showed that the seropositivity for all samples was 24.8%. At post‐mortem examination, 107 out of the 248 (43.1%) sheep scored seropositive had gross lesions of maedi; typical microscopic lesions were observed in 125 (50.4%) seropositive sheep, including the 107 with gross lesions. Of the 752 seronegative animals, only 13 (1.7%) sheep had macroscopic maedi‐like lesions. Seventeen (2.2%) of these seronegative cases, including those with gross lesions, had histologic pulmonary changes consistent with maedi. No other maedi/visna‐associated lesions were found during this study; however, coexisting secondary bacterial bronchopneumonia was frequently encountered. The association between serologic and pathologic findings is reported and discussed. Résumé Infection au Lentivirus Ovin (Visna‐maedi) au Maroc: Une Enquête Sérologique completée par Etude Anatomo‐pathologique Afin d'apprecier l'importance de l'infection Visna‐maedi du mouton au Maroc et d'étudier d'éventuels rapports existant entre les résultats sérologiques et les lésions pulmonaires, une enquête séro‐pathologique basée sur des visites aux abattoirs a été menée durant une période de deux ans. Les prélèvements de sang déstinés au sondage sérologiques ainsi que les poumons respectifs ont été effectués sur 1000 ovins, d'âge et de race différents, abattus au niveau de trois principaux abattoirs municipaux du Maroc (Casablanca, Kénitra, Rabat). La méthode sérologique d'immunodiffusion sur gélose (I.D.G) a révélé un pourcentage de positivité de 24,8% sur l'ensemble des échantillons testés. Quant à l'étude anatomo‐pathologique, elle a montré que 107 sur 248 (43, 1 %) animaux réagissants présentaient des lésions macroscopiques alors que 125 cas (50, 4 %) positifs, parmi lesquels figuraient les 107 ayant les lésions macroscopiques, avaient des lésions microscopiques typiques du maedi. Sur les 752 animaux séronegatifs, 13 (1, 7%) ovins seulement présentaient des lésions macroscopiques comparables à celles du maedi. Histologiquement, 17 cas séronégatifs, y compris ceux avec des lésions macroscopiques, avaient des lésions caractéristiques du maedi. Aucune autre lésion associée au complexe Visna‐maedi n'a été décelée, parcontre, des lésions de bronchopneumonie dûes à des surinfections bactériennes ont été communément rencontrées. Il convient donc de retenir une corrélation supposant une relation étiologique entre les constatations sérologiques et anatomo‐pathologiques.

Evaluation of histopathological on maedi disease with serological confirmation in North-East of Iran

“…The described pulmonary lesions are compatible with lesions previously described for maedi [15] and are essentially similar to those described for OPP [16,17], and serologically related viruses. The dominant feature was generalized lymphoid hyperplasia with massive peribronchiolar and discrete lymphoid follicles within lobules [7].…”

Seroprevalence of Visna-Maedi Virus (VMV) and Border Disease Virus (BDV) in Van province and around

“…The most important reason why the disease spreads is the sale of live animals, as first determined in Iceland and then in many European countries (Peterhans et al, 2004). Studies performed in Switzerland, Canada, Poland, Portugal, Morocco and the United States reported seropositivity rates of 9%, 19%, 24%, 34.3%, 24.8% and 26% respectively (Kita et al, 1990;Simard and Morley, 1991;Cutlip et al, 1992;Bouljihad and Leipold, 1994;Fevereiro, 1995;Schaller et al, 2000).…”

Irak, Erbil Bölgesinde Kronik Solunum Sistemi Hastalığı Olan Koyunlarda Maedi-Visna Hastalığının Serolojik Araştırılması

“…However, none of the animals in this study showed symptoms of arthritis (Table 4). (12)(13)(14)(15)(16)(17)(18). In many countries, MV was not described and investigated until now such as Algeria,…”

“…Incidence of the disease in Poland, Austria, Canada, USA, Morocco, Finland and Switzerland was reported as 24%, 9.5%, 19%, 26%, 24.8%, 1.6% and 9%, respectively (12)(13)(14)(15)(16)(17)(18). In many countries, MV was not described and investigated until now such as Algeria, Egypt, Lebanon, Libya and Tunisia (5).…”