Paratuberculosis in Cattle: International Evolution and Situation in Switzerland

A current overview of paratuberculosis describes this chronic disease of cattle, shows how it is being controlled internationally and in Switzerland, and explains why this is important.

Paratuberculosis (paraTB) appears in cattle and other ruminants as a disease proceeding over many years. It is symptomless at first, but chronic bowel inflammation with diarrhoea later leads to death. The Mycobacterium avium spp. paratuberculosis (MAP) bacterium is the cause of paraTB.

State of research on paratuberculosis

The article traces the current state of research on paraTB and MAP and discusses how various countries are controlling paraTB.

The first programmes to combat paraTB were launched over 30 years ago, when it was first mooted that MAP might be responsible for triggering the inflammatory bowel disorder Crohn’s disease in humans, and that it might survive the commercial milk pasteurisation process in certain circumstances.  

Despite intensive research over the ensuing decades, the possible causal connection between MAP and Crohn’s disease could neither be fully proven nor refuted.  Various clinical studies with validated methods for detecting MAP in clinical samples are still lacking. Nevertheless, the fight against paraTB is being expanded, especially in countries with large herds and intensive agriculture.

At present, the battle against paraTB is being fought in many countries through integrative herd management for the promotion of animal health and welfare whilst taking economic issues into account.

Situation in Switzerland

ParaTB is endemic in Switzerland. In late 2015 compulsory control measures against this epizootic disease were established at national level, primarily to safeguard access to the international market (the export of milk and dairy products). The aim is to identify and eliminate animals that excrete large amounts of the pathogen, thereby reducing infection pressure in the herd and lowering the potential risk of introducing MAP into the food chain.

The latest data from Prof. M. Meylan of the University of Bern show that, compared to the rest of Europe, Switzerland has a low herd prevalence in cattle farms: the true seroprevalence was 3.6% at herd level, as well as 3.6% at animal level in infected farms. Herd size was the only risk factor for a positive herd status. In addition, the study reveals that knowledge about paraTB among cattle farmers tends to be in rather short supply.