Prevalence of hepatic epithelioid macrophage microgranulomas due to Mycobacterium avium subspecies paratuberculosis in Lambs on the North Island of New Zealand.

Abstract

Paratuberculosis causes an infectious wasting condition of domestic cattle and other ruminants with heavy economic losses to domestic livestock industries worldwide. Paratuberculosis is caused by an infection with Mycobacterium avium subspecies paratuberculosis (MAP). Hepatic epithelioid macrophage (HEM) microgranulomas are found in some animals that are infected with MAP. This study, as part of a larger study, was conducted to give insight regarding the prevalence of HEM microgranulomas in lambs on the Manawatu region on the North Island of New Zealand. In total 400 liver samples of mixed breed lambs aged between 4 and 8 months were biopsied, stained and checked for HEM microgranulomas. No HEM microgranulomas were found in any of the 400 samples taken. Based on the current sample, with 95% certainty, the prevalence of HEM microgranuloma’s and MAP type 3c or 3b type lesions in lambs between 4 and 8 months old in the Manawatu region on the North Island of New Zealand is at least less than 0,75%. Further study is needed to give a better insight regarding the prevalence and etiology of MAP in lambs.