No abstract

Mycobacterium avium subsp. paratuberculosis, an acid-fast bacterium is the agent of Johne's disease, an intestinal disease that causes poor nutrient intake in ruminants. During the period 1987-2003, 322 of 777 (41.4%) goat herds and 97 of 458 (21.1%) sheep flocks were found to be infected with M.a.paratuberculosis in Northern Greece. From goats, mycobacteria were isolated from 238 of 652 (36.5%) of intestinal tissues, 14 of 119 (11.8%) of lymph nodes and five of 369 (1.4%) of faecal samples. From sheep, mycobacteria were isolated from 25 of 162 (15.4%) of intestinal tissues, three of 41 (7.3%) of lymph nodes and two of 322 (0.6%) of faecal samples. Isolates were typed by pulsed-field gel electrophoresis (PFGE) and restriction fragment length polymorphism followed by hybridization to IS900 [IS900- restriction fragment-length polymorphism (RFLP)]. IS900-RFLP BstEII profiles C1 and C5 and PFGE profiles [2-19] and [29-15] were identified. These PFGE profiles have not been found outside Greece to date.

The DNA probe test is a rapid and specific test that could be used in a control program if the sensitivity of the test were improved and possibly in combination with another test.

A large 7-year vaccination trial was conducted in 15 flocks of goats and 7 flocks of sheep, known to be infected with Mycobacterium avium subsp. paratuberculosis (MAP), in Northern Greece. A total of 3665 kids and 1685 lambs, 7-30 days old, were vaccinated during 1995-1999. Seven hundred and seventy-five kids and 413 lambs were kept as unvaccinated controls. For each trial, the Incidence Rate Ratio (IRR), with respective exact 95% confidence intervals, was calculated. All IRR point estimates for young animals were very large (from 5.68 to 11.78 for kids and from 4.28 to 10.08 for lambs), while none of the 95% confidence intervals included 1. The protective effect of vaccination was large and the difference in mortality among vaccinated and unvaccinated animals was more pronounced in young animals. The effect in adult animals was smaller than in young animals; it was, however, still considerable. Upon visual inspection of the K-M curves, it seems that for the young animal trials the vaccinated and control-group curves were diverging increasingly over time, which indicates that the gain from the vaccination (or the loss from non-vaccination) might increase over time during the trial.

Crohn's disease is a granulomatous ileocolitis of humans, of unknown aetiology, which generally manifests itself during the prime of life. The chronic, progressive clinical course and histological findings are consistent wiht a mycobacterial aetiology. Evidence supporting a pathogenic role for a mycobacterium has become available only in the last decade with the isolation of this microorganism from Crohn's disease tissue. M. paratuberculosis, which is the causative agent of Johne's disease in animals, has been identified in patients with Crohn's disease by PCR and DNA hybridisation techniques. It has been shown that isolates of M. paratuberculosis from Crohn's disease are indentical with pathogenic strains in ruminants.