Incidence of Mycobacterium avium subspecies paratuberculosis in bulk-tank milk samples from different regions in Switzerland

摘要

Mycobacterium avium subspecies paratuberculosis (MAP) is a pathogen causing chronic inflammation of the intestine in many animals, including primates, and is considered to be implicated in Crohn's disease in human beings (Hermon-Taylor and others 2000). Crohn's disease is a chronic granulomatous ileocolitis of humans, with significant similarity to paratuberculosis. High herd prevalences of MAP have been found in dairy cattle in particular (Thorne and Hardin 1997). A recent USDA survey indicated that 41 per cent of dairy herds in the USA have at least one MAP ELISA-positive animal. Roughly 22 per cent of all dairy herds in the USA have at least 10 per cent of animals testing positive (Collins 1998). It has long been known that MAP can be culturedfrom the milk of cows clinically infected with paratuberculosis (Taylor and others 1981). Recent work has shown that MAP can also be cultured from the milk of apparently healthy, subclinically infected cows (Sweeney and others 1992, Streeter and others 1995). Moreover, thermal tolerance data indicate that this organism is more heat resistant than other Mycobacterium species and is capable of surviving the pasteurisation of raw milk (Chiodini and Hermon-Taylor 1993, Grant and others 1998, Sung and Collins 1998).