Invasive Species Compendium

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Abstract

Sporadic Bovine Encephalomyelitis (Buss Disease).

Abstract

II. A further account of " Buss encephalomyelitis " in which the authors describe the histological appearance of the lesions found at autopsy. It has been found that in calves the subcutaneous route of inoculation of infective material is fully as satisfactory as the intra-cranial. Subcutaneous or intramuscular inoculations with infective material cause a localized reaction, which histologically is characterized by a cellular infiltration composed chiefly of monocytes, some oedema, and a pale staining of the muscle fibres. When calves are injected on the side of the neck, the prescapular and other lymph nodes in this region become enlarged. The spread of the " virus " in the body, apparently via the lymph stream, is slow, and after a prolonged illness most of the lymph nodes become moderately enlarged. There are no macroscopic lesions of the brain or cord. Microscopic lesions consist of a perivascular cuffing with monocytes, focal areas of monocytic infiltration with some liquefactive necrosis, and cell infiltration and oedema of parts of the meninges. The " virus " also seems to affect the nasal passages since these are congested and contain catarrhal exudates. After tibe disease has progressed for some days, a serofibrinous pleurisy and peritonitis develop.
One attack of the disease apparently gives some protection against further exposures. Serum from recovered calves does not protect susceptible animate, although there is some evidence that " immune " serum does delay the onset and reduce the severity of the symptoms and lesions. Inoculation of killed infective material does not produce an immunity.
The causal agent of the disease has not been identified in spite of intensive efforts. Details are given of experimental work with g. pigs, in which the main lesions are peritonitis and pleurisy, rarely encephalitis. The " virus " of the disease has been propagated on chick embryos for over 60 days in serial passage. It appears that the " virus " is not filtrable through Berkefeld N filters.-N. J. SCORGIE.