LISTERIOSIS

LISTERIOSIS


Until the 1980s listeriosis was rarely reported in humans but was fairly common in animals. Since then, there have been increased reports of listeriosis in people. In animals listeriosis is also known as circling disease or silage disease.








LISTERIOSIS IN ANIMALS


The most frequently seen form of listeriosis in animals is encephalitis, seen in adult ruminants and, rarely, in adult pigs. Sheep and goats are most susceptible to L. monocytogenes infection. The disease is one of winter and spring, because this is a time when animals are confined and fed silage or hay. If either the silage or hay has been contaminated with L. monocytogenes, it could be a source of infection to the animals.


The organism enters the body through abrasions in the mouth and travels to the brain, where it causes unilateral encephalitis. The incubation period is about 10 days. The signs exhibited by an infected animal include depression, fever, and incoordination. Infected animals will segregate themselves into corners and frequently are seen leaning against a fence or building. An infected animal may start circling in one direction. The direction is determined by the side of the brain affected (Figure 25). If the facial nerve is affected, it will be unilateral and will be seen as a drooping ear, drooping eyelid, dilated nostril, drooping lower lip, tongue protrusion, excessive salivation, and difficulty eating. As the disease progresses, the animal becomes progressively paralyzed, will fall down on its side and paddle its legs as if running, enter into a coma, and eventually die. The mortality rate can be as high as 70% in sheep. Cattle seem to be a bit more tolerant, but the mortality rate can still reach 50%.


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Oct 1, 2016 | Posted by in EXOTIC, WILD, ZOO | Comments Off on LISTERIOSIS

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