Difference between revisions of "Mycobacterium avium subsp. paratuberculosis"
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| − | # | + | ===[[Intestines Proliferative Enteritis - Pathology#Paratuberculosis (Johnes disease)|Johne's Disease (paratuberculosis)]]=== |
| + | |||
| + | *[[Intestines Proliferative Enteritis - Pathology#Paratuberculosis (Johnes disease)|Johne's Disease]] is a chronic, contagious enteritis of ruminants | ||
| + | *Caused by ''M avium'' subsp. ''paratuberculosis'' | ||
| + | |||
| + | *Epidemiology | ||
| + | **Transmitted to young calves by ingestion of mycobacteria in faeces of infected adults | ||
| + | **Organisms viable in environment for long periods | ||
| + | **Long incubation period with clinical signs appearing in cattle over 2 years of age | ||
| + | **Subclinical carriers can occur, shedding organisms in their faeces | ||
| + | |||
| + | *Pathogenesis and pathogenicity | ||
| + | **''M avium'' subsp. ''paratuberculosis'' is an intracellular pathogen | ||
| + | **Mycobacteria are ingested by macrophages in the Peyer's patches | ||
| + | **Survival and replication of mycobacteria in macrophages initiate an immune-mediated granulomatous reaction | ||
| + | **Lymphocytes and macrophages accumulate in the lamina propria and submucosa, resulting in marked thickening and folding of the intestinal wall | ||
| + | **Mesenteric lymph nodes are enlarged | ||
| + | **A protein-losing enteropathy results, along with failure to absorb nutrients and water | ||
| + | |||
| + | *Clinical signs | ||
| + | **Diarrhoea, initially intermittent, and weight loss in cattle | ||
| + | **Weight loss in sheep and goats | ||
| + | **Rapidly fatal with weight loss and diarrhoea in some deer | ||
| + | |||
| + | *Diagnosis | ||
| + | **All diagnostic procedures have faults but include: | ||
| + | **Microscopy of rectal biopsies | ||
| + | **Faecal culture | ||
| + | **Serology of serum including complement fixation tests, agar-gel immunodiffusion test and an ELISA | ||
| + | **Histopathology of intestines and lymph nodes | ||
| + | **Isolation and identification of mycobacteria from faeces and tissues | ||
| + | **Ziehl-Neelson-positive smears | ||
| + | **Intradermal tuberculin test | ||
| + | **DNA probes for detection in faeces | ||
| + | |||
| + | *Control | ||
| + | **Slaughter of affected animals | ||
| + | **Detection and slaughter of subclinical shedders using faecal culture, DNA probes and ELISA | ||
| + | **Good hygiene to protect young calves | ||
| + | **Separation and isolation of calves from affected dams | ||
| + | **Inactivated adjuvanted vaccines are available and reduce shedding of mycobacteria but do not eliminate infection[[Category:Mycobacterium_species]][[Category:Cattle]] | ||
Revision as of 11:00, 14 May 2010
Johne's Disease (paratuberculosis)
- Johne's Disease is a chronic, contagious enteritis of ruminants
- Caused by M avium subsp. paratuberculosis
- Epidemiology
- Transmitted to young calves by ingestion of mycobacteria in faeces of infected adults
- Organisms viable in environment for long periods
- Long incubation period with clinical signs appearing in cattle over 2 years of age
- Subclinical carriers can occur, shedding organisms in their faeces
- Pathogenesis and pathogenicity
- M avium subsp. paratuberculosis is an intracellular pathogen
- Mycobacteria are ingested by macrophages in the Peyer's patches
- Survival and replication of mycobacteria in macrophages initiate an immune-mediated granulomatous reaction
- Lymphocytes and macrophages accumulate in the lamina propria and submucosa, resulting in marked thickening and folding of the intestinal wall
- Mesenteric lymph nodes are enlarged
- A protein-losing enteropathy results, along with failure to absorb nutrients and water
- Clinical signs
- Diarrhoea, initially intermittent, and weight loss in cattle
- Weight loss in sheep and goats
- Rapidly fatal with weight loss and diarrhoea in some deer
- Diagnosis
- All diagnostic procedures have faults but include:
- Microscopy of rectal biopsies
- Faecal culture
- Serology of serum including complement fixation tests, agar-gel immunodiffusion test and an ELISA
- Histopathology of intestines and lymph nodes
- Isolation and identification of mycobacteria from faeces and tissues
- Ziehl-Neelson-positive smears
- Intradermal tuberculin test
- DNA probes for detection in faeces
- Control
- Slaughter of affected animals
- Detection and slaughter of subclinical shedders using faecal culture, DNA probes and ELISA
- Good hygiene to protect young calves
- Separation and isolation of calves from affected dams
- Inactivated adjuvanted vaccines are available and reduce shedding of mycobacteria but do not eliminate infection