Isolation and biological properties of some Moroccan strains of Newcastle disease virus.

Newcastle disease virus was isolated from six field cases in Morocco. On the basis of the mean death time of chicken embryos, the intracerebral pathogenicity index, and plaque formation on chicken embryo fibroblast monolayers, five isolates were determined to be of the velogenic pathotype. One of these differed from the others in that it agglutinated equine erythrocytes. The sixth isolate was found to be of low virulence but differed from the vaccinal strain tested.

Comparison of the efficacy of Brucella abortus strain RB51 and Brucella melitensis Rev. 1 live vaccines against experimental infection with Brucella melitensis in pregnant ewes.

To test the efficacy of rough Brucella strain vaccines in sheep, a vaccine recently developed in cattle (Brucella abortus strain RB51) was assessed in comparison with the conventional Rev. 1 vaccine. Forty-five ewes from twelve to fourteen months of age, from brucellosis-free flocks, were allotted to three groups of fifteen ewes each. Group one was vaccinated by the conjunctival route with 1.73 x 10(8) colony forming units (CFU) of Rev. 1 vaccine. Group two was vaccinated subcutaneously with 11 x 10(9) CFU of RB51 vaccine and group three was considered as a control. All sheep were challenged at two to three months of gestation with 5 x 10(7) CFU of virulent B. melitensis H38. Vaccination with RB51 vaccine did not result in the production of any antibodies against the O-side chain of lipopolysaccharide, as measured by conventional serological tests (Rose Bengal plate test and complement fixation test). Protection of sheep against abortion and excretion of virulent Brucella strain in vaginal fluid, aborted foetuses and/or non viable lambs at parturition and abortion was significantly lower than that afforded by Rev. 1 vaccine. The difference compared to the control group was not significant. Data from this study suggest that the RB51 vaccine used for cattle vaccination does not provide effective protection of sheep against abortion induced by B. melitensis.

First report of paratuberculosis (Johne's disease) in sheep in Morocco.

Paratuberculosis (Johne's disease) was suspected in a flock of approximately 1000 sheep after weight losses and scouring had increased in adult animals despite repeated anthelmintic treatment. A total of 10 ewes showing clinical symptoms were submitted to laboratory examination. Gross pathological and histological examination of tissue samples rendered results compatible with Johne's disease in all 10 ewes. The diagnosis could only be confirmed by cultural isolation and identification of Mycobacterium paratuberculosis in the faeces of two ewes. This is considered the first documented isolation of Mycobacterium paratuberculosis in sheep in Morocco.

[Epidemiology of diarrhea caused by Escherichia coli and rotavirus in calves and lambs in Morocco]. / Epidèmiologie des diarrhées à Escherichia coli et à rotavirus chez le veau et l'agneau au Maroc.

An epidemiological survey on E coli and rotavirus associated diarrheas in one to twenty five days old calves and lambs was made in three regions: Rabat-Kenitra, Marrakech and Agadir. Isolated E coli K99 stains have been studied of a biochemical, serotypical (O antigen) and antibiotypical point of view. The identification of rotavirus was made by ELISA test. Persistence of K99 antigen and heat stable toxin A was examined after a conservation of 5 weeks at - 18 degrees C. The frequency of E coli K99 or rotavirus associated diarrheas is respectively 26.9% and 29.7% in calf, 10% and 30% in lamb. This incidence considerably decreases from the 20th day in calf and from the 11th day in lamb. It must be observed that 34.8% of cases of diarrheas in calf and 55% in lamb cannot be ascribed to investigated agents. Only 12 out of 42 E coli K99 strains belong to serogroups O101, O8 and O9. Preservation of strains to - 18 degrees C comes with the loss of K99 antigen. These strains are not toxinogens. Among the strains having kept this antigen, 29% are toxinogens. Surveyings of antibiotics resistance was discussed.