National Reference Laboratory for Paratuberculosis
Institute of Molecular Pathogenesis
Paratuberculosis, also called „Johne´s disease“, is a chronic inflammatory intestinal disease of ruminants caused by Mycobacterium avium subsp. paratuberculosis (Map).
After a latency period of several years clinical symptoms (diarrhea, weight loss and fatigue) are only visible in the final stage of the disease. However, Map is shed in high amounts via faeces also before clinical symptoms occur. Young animals are most susceptible for infection. Paratuberculosis is spread via trade with clinically healthy, latently infected animals.
The disease, which is reportable in Germany, has been reported from all regions of the country. Up to now it was detected in cattle, sheep, goats, red deer, roe deer und in a donkey. It causes considerable direct and indirect economic losses which are most severe in dairy herds (reduced milk yield, diminished slaughter value because of weight loss, increased susceptibility to other diseases, direct animal losses).
The zoonotic potential of the disease is controversial. Ongoing discussion and research addresses the role of Map in Morbus Crohn, a chronic inflammatory bowel disease of man.
Diagnosis of paratuberculosis is based on the detection of the causative agent in faeces and tissues or on detection of antibodies in blood serum or milk. Detection of the causative agent is done by bacterioscopy (Ziehl-Neelsen staining) or by bacteriological culture followed by identification of the Map genome by PCR. When Map is shed in high amounts, diagnosis is also possible by PCR using nucleic acids directly extracted from faeces. Target regions for PCR can be IS900, f57 and others (Möbius et al., Vet. Microbiol. 126: 324-333, 2008.). In 2012, a commercial real-time PCR system was licensed for the direct detection of Map in faecal samples.
At present (12/2012), four ELISA assays for the detection of antibodies against Map in serum and milk samples of cattle and in part also of small ruminants are licensed in Germany.
Direct detection of Map as well as antibody detection are characterised by a limited sensitivity. Using these methods, diagnosis of the disease in young animals (up to an age of 2-3 years) is almost impossible. Even in older animals repeated testing is necessary to increase the detection rate. Antibody detection in serum or milk samples of individual animals is only useful for the classification of the infection status of the herd. Prevalence estimation is difficult with the established diagnostic methods.
- Volatile organic compounds (VOC) of causative agent and host as biomarker for bacterial infections. (DFG, 2012-2015, Collaboration with WG Pathology and Pathophysiology of the IMP)
- Identification of host-derived biomarkers of latent infections with Mycobacterium avium ssp. paratuberculosis (MAP). (Part of the EMIDA-ERA-Net consortium „Mycobactdiagnosis“, 2012-2015)
- Differentiation of Mycobacterium avium subsp. paratuberculosis isolates – Relation between genotype and phenotype. (Partner VI: BMBF-Consortium „ZooMAP“, 2010-2013)
- Development of improved test systems for the diagnosis, development and testing of vaccines for paratuberculosis. (FLI, Animal Health Insurance (AHI) of Baden-Wuerttemberg, AHI of Hesse, AHI of Mecklenburg-West Pomerania, AHI of Lower Saxony, AHI of Rheinland-Palatine, Thuringian AHI, 2009-2012)
- Veterinary Network of Laboratories Researching into Improved Diagnosis and Epidemiology of Mycobacterial Diseases. (Co-ordination Action SSPE-CT-2004-501903, VENoMYC, EU, 2004-2010)
- Differentiation of Mycobacterium avium subsp. paratuberculosis isolates of different origin with a standardized typing protocol. (Partner VI: BMBF Consortium „ZooMAP“, 2007-2010)
- Evaluation of the efficiency of vaccination for controlling paratuberculosis in cattle. (FLI, 2007-2009).
Overview of methods
- Cultural isolation of Map and other mycobacteria from faeces and tissue
- Cultural examination of mycobactin-dependence of Map
- Direct detection of Map in faeces, tissue and environmental samples using real-time PCR
- Molecular typing of Map using PCR, PCR-REA, RFLP, MIRU-VNTR and MLSSR
- Detection of antibodies against Map in serum and milk using ELISA
Overview of services
- Consultant for federal and state authorities regarding diagnosis and control of paratuberculosis
- Clarification of ambiguous test results
- Molecular typing of Mycobacterium avium subsp. paratuberculosis isolates
- Supply of reference material (serum, milk samples)
- Experimental evaluation of diagnostic kits for licensing
- Organization of national proficiency tests
- Panels of serum and milk samples from proved paratuberculosis positive or negative cattle
- Reportable animal disease act of 20 December 2005 (BGBl. IS. 3517)
- Guidelines for the management of paratuberculosis in ruminant herds (Paratuberculosis Guidelines), BAnz. vom 10.02.2005, S. 2165