Mycobacterium avium subsp. paratuberculosis (MAP) (Johne´s disease).
Version 02-01-2012

Mycobacterium avium subsp. paratuberculosis (MAP) is a multihospedador intestinal pathogen causing chronic histological several types, which affects herbivores inflammatory disease Johne (Johne's disease) or paratuberculosis, and systemic disease.

Animals may be infected through breast milk, through food, or environmental pollution. When it reaches the digestive tract, the bacteria invade intestinal macrophages. The incubation period until the onset of symptoms may be long, but infected, even without symptoms, eliminate bacteria that can infect other animals. Animals affected by Johne's disease develop chronic granulomatous enteritis which is accompanied by weight loss and sometimes diarrhea, decrease their milk production and may die. It is an untreatable disease that involves the slaughter of sick animals, which represents a significant economic loss. Infected animals shed abundant in bacilli in the environment, which along with its prolonged survival in the environment, facilitate the spread.

People could spread from the environment or through milk, having demonstrated its presence even in pasteurized milk. It demonstrated a significant relationship between mycobacteria species and chronic intestinal inflammation in human Crohn's disease. However, some studies have not confirmed, probably because of differences in methods or samples studied. However, in 2008, the American Academy of Microbiology concluded that the MAP association with Crohn's disease is not questionable, but their role in causality still needs to be demonstrated. In irritable bowel syndrome (IBD: Irritable Bowel Syndrome) has also demonstrated its presence and a study has shown to correlate with the consumption of cheese craftsmanship. The latter process is characterized by persistent abdominal discomfort or pain, along with diarrhea, constipation, or both, in the absence of organic disease manifests and an apparently normal endoscopic examination. These patients sometimes accompanied by lethargy, backaches and muscle, headaches , and urinary disorders. Recently found enteric nervous system abnormalities, with histopathologic evidence and functional changes caused by moderate immune activation.

Diagnosis in animals and people is conditioned by the slow multiplication of this bacteria and its special nutritional requirements. Samples may be stool, peripheral blood, milk, lymph node or intestinal biopsy taken at necropsy. Culturing the veterinary samples usually performed between HEYM (Herrold's Yolk Agar Egg) supplemented with mycobactin J. These cultures should be followed for at least about 16 weeks, then must be confirmed isolates by Ziehl-Neelsen stain, subcultured means without mycobactin and detection of DNA sequence IS900. However, currently it is also being applied in liquid culture (migt) which reduces tracking time about 6 weeks. In animals, to facilitate the diagnosis of infected, have been used to detect antibody tests (ELISA), but these tests are very sensitive, especially at the onset of the disease, even when there are no symptoms. Therefore, the finding of antibodies only allows a diagnosis of suspicion.

Molecular methods (PCR), through the detection of DNA sequence IS900, allowed obviate many of the drawbacks existing in the diagnosis of this infection. Thus allow diagnosis more quickly, can confirm his presence in culture without performing subcultures on media with and without mycobactin, and have been applied to various types of samples (stool, biopsies of intestinal mucosa, lymph node biopsies, and peripheral blood mononuclear cells).

Tests in IVAMI:
  • PCR: IVAMI performed in detecting Mycobacterium avium subsp. paratuberculosis (MAP) by extracting DNA from any of the samples received (see below ), the amplification of the sequence IS900 MAP PCR, and confirmation of the specificity of the test by sequencing amplified. This test is the most currently used both to detect the genome of MAP in clinical samples, as well as to confirm that a mycobacterium developed in a culture inoculated with a sample is MAP, without having to wait to make subcultures on media without micobactine so it takes a lot to provide identification.

  • Cultivation: Mycobacterium avium subsp. paratuberculosis (Johne 's bacillus) has a very slow growth with special nutritional requirements. For this reason, usually not grown in any microbiology laboratory. However, if you wish we can do it in BACTEC MGIT media supplemented with Mycobactin J, with a monthly monitoring crops for a year at least, so the cost is higher.

Samples recommended for animals feces, peripheral blood extracted with EDTA, and milk. If necropsy, intestinal biopsy, lymph node

Samples recommended for people: biopsies of the peripheral area of the lesion, thus avoiding the base ulcerations with fibrous content. Other alternatives samples: Peripheral blood collected with EDTA.