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ARS Home » Midwest Area » Ames, Iowa » National Animal Disease Center » Virus and Prion Research » Research » Publications at this Location » Publication #95811
Title: IMMUNOHISTOPATHOLOGICAL FINDINGS IN AN ADULT LLAMA WITH LISTERIOSIS

Author
item Hamir, Amirali
item MOSER, G - SELF EMPLOYED

Submitted to: Veterinary Record
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/2/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary: Listeriosis is a zoonotic disease which is caused by bacteria. In cattle, sheep and goats it causes tiny abscesses in the brain. Since there is paucity of published information on lesions of listeriosis in South American camelids, the information obtained from other domestic ruminants has been asumed to be applicable for these species. In llamas, however, the lesion appears to manifest as meningitis. This suggests that the mechanism of the disease in these species is fundamentally different from that of other domestic ruminants. Therefore, an understanding of this bacteria and its disease process is warranted. In this communication we describe lesions and laboratory findings of listerial meningitis in a llama. In the presently described case the llama not only had meningitis, but also, revealed lesions in the spleen. The routine histology failed to demonstrate the organisms. However, by a special staining technique the bacteria were observed in both the spleen and the meninges. It is our opinion that in llamas listeriosis is not manifested as small abscesses in the brain, but is seen as meningitis. However, more research on listerosis in llamas is required to validate this hypothesis.

Technical Abstract: Listeriosis is a zoonotic disease caused by Listeria monocytogenes, a gram-positive intracellular coccobacillus. In domestic animals, three forms of the disease have been described (encephalitis, septicemia, and abortions). In cattle, sheep, and goats the encephalitic form of listeriosis is histolopathogically characterized by the presence of multifocal microabscesses with intralesional gram-positive bacteria in brain stem and/or medulla oblongata. In llamas, however, the lesion appears to manifests as suppurative meningitis. These findings suggest that the pathogenesis of the disease in these species is fundamentally different from that of other domestic ruminants. Therefore, a detailed understanding of this pathogen and its pathogenesis is warranted. In this communication we describe pathological and immunohistochemical findings of listerial meningitis in a llama. In the presently described case the llama not only had suppurative meningitis, but also, revealed multifocal acute necrotising spleenitis. The histochemical stains (HE and Gram) failed to show the aetiological agents. However, by immunohistochemistry the Listeria antigen was observed within the inflammatory cells in both the spleen and the meninges. It is our opinion that in llamas the encephalitic form of listeriosis is not manifested as microabscesses in brain, but is seen as suppurative meningitis. However, more research on listeriosis in South American camalids is required to validate this hypothesis.