Mycobacterium avium subspecies paratuberculosis (MAP)
Clinical symptoms develop after an incubation period of many years in some of the infected animals and are manifested by insatiable diarrhoea with a preserved desire to eat. The faeces are foamy and interspersed with gas bubbles. Other symptoms are severe emaciation and a decrease in milk yield. In the small ruminant, emaciation is often the only symptom. The disease inevitably leads to the death of the affected animals.
Situation in Austria
In Austria, since April 2006, there has been a notification requirement for the clinical form of paratuberculosis in cattle, sheep and goats as well as wild ruminants kept in gates. The aim of this surveillance programme is to identify animals clinically affected by paratuberculosis and to remove them from the herds. Furthermore, after laboratory confirmation, targeted hygiene and management measures are taken to reduce the infection pressure in the affected herds.
Infection occurs predominantly in the first months of life. Young animals are the most susceptible; infection often occurs directly after birth via pathogen-containing faeces, faeces-contaminated milk and teats as well as colostrum.
MAP control is made considerably more difficult by various factors. While the laboratory diagnosis of an infection in clinically ill animals is usually not difficult, early stages of infection are often difficult to detect due to the long incubation period, the intermittent excretion of the pathogen and the relatively late seroconversion. However, since it is the clinically ill animals that are most important in the spread of MAP because of the high excretion of the pathogen, the surveillance and control programme is aimed primarily at the detection and eradication of animals clinically ill with paratuberculosis. If the actual existence of clinical paratuberculosis is detected and confirmed, additional targeted hygiene and management measures to reduce the infection pressure in the affected herds shall follow the culling of the affected animals.
Based on the clinic, only a tentative diagnosis can be made, which must be verified by further laboratory diagnostics.
The following laboratory diagnostic methods are used:
- Pathogen detection: bacteriological culture test and PCR.
- Detection of MAP-specific antibodies: ELISA
For the diagnostic clarification of clinical suspect cases, blood and faeces samples must be sent in by the official veterinarian. In the case of dead or killed animals, organ material (intestinal parts, lymph nodes) is to be sent in.
Last updated: 01.06.2023