Spontaneous listeric encephalitis and neuritis in sheep. Light microscopic studies

Sixteen of 17 sheep with spontaneous listeric encephalitis had neuritis characterized by diffuse and focal intrafascicular and perineural accumulations of lymphocytes, plasma cells, macrophages and neutrophils in one or more cranial nerves. Nine sheep had extensive trigeminal neuritis which was usually unilateral. Brain lesions were mainly in the stem and were foci of macrophages or neutrophils or both, malacia, neutrophilic neuronophagia, vascular cuffing, and meningitis. Lesions in the brain and trigeminal ganglia were most severe on the same side as the affected trigeminal nerve. Gram-positive bacilli were in proximal parts of cranial nerves in foci of inflammatory cells and occasionally in morphologically intact nerve fibers. Organisms in the brain were in phagocytes in areas of inflammation and in scattered neurons and axons. The results were consistent with centripetal migration of the infectious agent along one or more branches of the trigeminal nerve to the brain and dissemination in the brain stem occurring, at least partly, along fiber tracts. Intraaxonal movement of bacteria probably is a mechanism involved in the pathogenesis of this disease.     

Epizootiology of bovine rotavirus infection.

Published information on rotaviruses as pathogens, the source of virus infection and the method of transmission of infection under normal conditions are reviewed. The antigenic differences between rotavirus isolates from children, calves, pigs, foals and mice are discussed. Bovine rotaviruses isolated in the USA and the UK were shown to be closely related antigenically and the US vaccine strain protected calves from challenge with the UK rotavirus. Nineteen normally reared calves, with 20 or more ZnSO4 units of serum delta globulin, were susceptible to rotavirus inoculation at two days of age. They developed diarrhoea, showed body weight loss but recovered. Three calves with less than 10 ZnSO4 units of serum delta globulin developed diarrhoea and died. In a serological survey of 654 adult cows and calves from three herds, between 2 per cent and 37 per cent of individuals in a group had low rotavirus antibody titres and were probably susceptible to rotavirus infection. These were found in all age groups of animals studied, whether or not the group had suffered a recent rotavirus epizootic. It was not possible to predict whether an epizootic would develop on the basis of a serological survey.     

Epizootiology of Salmonella typhimurium infection in chickens]

The incidence of S. typhimurium infections among fowl increased in thr region of Potsdam in general, and on various big farms in particular, 1976 and over the first half of 1977. The outbreaks included subclinical infections and clinically manifest diseases which caused remarkable loss of broilers from the affected stocks (up to 15.92 per cent). Parent stocks contaminated with S. typhimurium were to be the sources of infection in all cases. A total of 1,220 Salmonella strains were isolated from fowl and its environment, with 1,151 of them being S. typhimurium (2.98 per cent of all samples tested). The following amounts of S. typhimurium strains were isolated from different types of samples which had been collected from infected broiler stocks: 8.10 per cent from dead broilers, 5.86 per cent from dead broiler parents, 2.11 per cent from pulp linings of transport cages for day-old chicks, 1.23 per cent from litter, 1.0 per cent from hatching material (eggs or dead and jammed embryos, and 0.12 per cent from swabs used in hygiene supervision). No Salmonellae were isolated from feedstuff. The transmission of S. typhimurium, therefore, is though to have taken the route via the hatching egg and via congenitally infected chicks traded between breeders and propagation farms. The control and prophylaxis of S. typhimurium infections, therefore, should be based primarily on action in the centralised breeding stocks. Specific steps of such action are proposed. Fifty-three strains were biochemically and lysotypically analysed, with the following types being determined: ut/Ph 30 BT b, ut/Ph 30 BT c, n.c. 1/72/n.c. BT b, 2 n.c. BT a, and 1A/6 BT a. The first two types covered 84.9 per cent of all strains isolated from the fowl. All lysotype ut/Ph 30 strains isolated from fowl fell under the copenhagen variant which had rarely been isolated from man in the past. These results are likely to support the demand for a joint control programme for enteritis Salmonellae, with particular emphasis on S. typhimurium, for implementation in human and veterinary medicine.     

Epizootiology of fowls adenoviruses

Fowl adenoviruses of the serotype 4 from Germany were characterised by restriction enzyme analysis in comparison to isolates from Asia, South America and the FAV4 reference strain KR5. Only strain Da60 which was isolated from a psittacine aviary was identical with the reference strain KR5. None of the isolates was identical with the highly pathogenic strains from India and Ecuador. One-day-old chicks were infected orally and intramuscularly with the reference strain KR5, the psittacine isolate Da60 and isolate K1013 from Ecuador. Whereas no mortality was seen with the two strains KR5 and Da60, the mortality with K1013 was 100%. The main pathological signs were a swollen liver with necrosis and a lymphocyte depletion with a loss of the follicle structure. To investigate a second subject of avian adenovirus epizootiology several FAVs were characterized serologically and with PCR which was combined with the digestion of the PCR products. Including the reference strains, both methods were compared. It was shown that the digestion of the PCR products allows a clear attribution to a specific serotype, which underlines the usefulness of this method for diagnostic purposes.     

Atypical parapoxvirus infection in sheep

This report describes the clinical and laboratory findings for 5 sheep from 3 different flocks with extensive proliferative skin lesions grossly resembling warts on the distal limbs. The lesions affected the front and rear extremities in all sheep, and 2 sheep also had lesions around the head. The sheep exhibited signs of pain when the lesions were touched, and most sheep were reluctant to move. Various empirical treatments, including systemic antibiotics, topical antibiotics, and antifungal ointments, were administered without clinical improvement. Diagnostic tests including skin biopsy and histopathology, examination of skin scrapings, bacteriology, mycology, electron microscopy of lesions, and immunohistochemical analysis demonstrated that the lesions were the result of parapoxvirus infection. All 5 animals were euthanized either because of the lack of resolution of clinical signs or a decision by the owner. These animals illustrate an atypical presentation of parapoxvirus infection in sheep (orf, contagious ecthyma, and scabby mouth). The infection appeared to be minimally contagious; however, the lesions did not spontaneously resolve. This appears to be the 1st report of such lesions in multiple sheep in North America, although similar lesions have been reported in Israel and the United Kingdom.     

ExperimentalSchistosoma mansoni infection in sheep

Summary Sheep are partially susceptible toSchistosoma mansoni infection. However, development of worms is slow and they are reduced in size. No anaemia is produced in the infected animals, but a moderate degree of eosinophilia occurs at a late stage. The peculiar pathological lesions observed in the liver of ruminants is recorded and a simple technique suitable for perfusion of adult schistosome worms in large animals is described.

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Sumario Los ovinos son parcialmente susceptibles a la infección conSchistosoma mansoni. Sin embargo, el desarrollo de los parásitos es lento y tambien estan reducidos en tama?o. No se produce anemia en los animales infectados pero si ocurre un grado moderado de eosinofilia en los estadíos finales. Las lesiones patológicas peculiares observadas en el hígado de los rumiantes son descritas y tambien una tecnica simple adecuada para la perfusión de schistosomas adultos en animales mayores.

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Résumé Les moutons sont fablement sensibles à l'infection àSchistosoma mansoni. Toutefois, le développement des vers est lent et ceux-ci ont une taille réduite. Les animaux infectés ne présentent pas d'anémie, mais une éosinophilie modérée se produit à un stade avancé. Les lésions pathologiques spécifiques observées dans le foie des ruminants sont décrites, ainsi qu'une technique simple de perfusion de schistosomes adultes chez les grands animaux.

     

Salmonella gona infection in sheep

A field outbreak of salmonellosis due to Salmonella agona in sheep and some subsequent experimental work is described. While the field outbreak in pregnant ewes and neonatal lambs caused severe losses the experimental disease in non-pregnant sheep was mild and transient. S agona was not isolated from the carcases of the experimental sheep killed after 28 days post infection but it persisted for 69 days in the faeces of one ewe which was kept alive for three months. Media comparisons indicated that selenite enrichment broths incubated at 43 degrees C and plated on to brilliant green agar gave the most satisfactory cultural results.     

Epizootiology of fascioliasis in Montana.

During 1989-1990, the United States Department of Agriculture (USDA) meat inspection records were used to determine the distribution and incidence of liver flukes (Fasciola hepatica and Fascioloides magna) in Montana cattle. Of the cows and bulls slaughtered in USDA-inspected packing plants during a 12 month time period, 17.24% had livers that were condemned because of liver flukes. This was a 12% increase over USDA liver condemnations reported for 1973. Infected animals have been reported from 26 counties in Montana, mostly located in the south-central and western half of the state. Forty-nine percent of the 2.4 million cattle in Montana are raised in these counties. Lymnaeid snail species that may serve as intermediate hosts for Fasciola hepatica were found in most of the counties where liver flukes were reported. The principal vectors believed to be responsible for the transmission of Fasciola hepatica in Montana are species of the genus Fossaria. Stagnicola montanensis and Lymnaea stagnalis, which may serve as intermediate hosts for this parasite have also been collected. A known intermediate host for Fascioloides magna, Stagnicola caperata, was also found in several locations.