Prevalence and spectrum of Johne’s disease lesions in cattle slaughtered at two abattoirs in Kampala, Uganda: Poster 131. 56th AAVLD/117th USAHA Annual Meeting Proceedings

This study was conducted to determine the prevalence and characteristics of Johne’s disease (JD) lesions in Ugandan cattle slaughtered at two of the main abattoirs in Kampala. JD, or paratuberculosis, is a chronic wasting
disease that affects a wide range of domestic and wild animals and is caused by Mycobacterium avium subspecies paratuberculosis (MAP), an acid-fast bacterium. It has serious negative impact on the productivity of the affected
animals. The control and eradication of the disease is constrained by the lack of early diagnosis tools. Identification of the affected animals can be based on clinical signs, demonstration of the organism in feces and tissues of affected
animals using various bacteriological and molecular methods; serological testing in live animals, and gross and microscopic lesions. In countries where JD has never been reported or has very low prevalence, facilities for culture
and molecular diagnosis of the disease might not be in existence. Under such circumstances, pathological diagnosis is very important. Although gross lesions can lead to a correct diagnosis of the disease in advanced stages, in some
cases, even animals with advanced disease may lack such lesions. Moreover, in early stages of the disease, the lesions may be so subtle as to escape recognition. Ileocecal junction and the associated lymph nodes of 1,022 cattle
were examined for gross and microscopic lesions, followed by Ziehl Neelsen staining of the tissues bearing lesions. Confirmation of MAP infection was done in some of the tissues using culture and IS900 PCR. The lesions were then
described, characterised and tabulated. Characteristic JD granulomas were found in 4.7% of the samples examined, derived from Zebu, Ankole longhorn, Friesian breeds of cattle and their crosses. Lesions were found both in the
lymph nodes and ileocecal junction mucosa. The lesions tended to be more severe in the lymph node than in the mucosa. There were also some unique and atypical lesions found in association with JD granulomas. The diagnostic
value of various gross lesions and criteria of lesion classifications and diagnosis are revisited and discussed based on the findings of this study. The prevalence of JD lesions among slaughtered cattle in Kampala’s two abattoirs
indicates that the disease is well established in the cattle population in the country. The diverse manifestations in lesions of JD, particularly early, focal or mild lesions, need to be considered when making histological diagnosis in
tissues where the disease is suspected.