Difference between revisions of "Anthrax"
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===Description=== | ===Description=== | ||
| − | Anthrax is a serious, often fatal zoonotic disease of wild and domestic mammals caused by the spore-forming bacterium [[Bacillus anthracis]]. There are three main forms of the disease; gastrointestinal, pulmonary or cutaneous. | + | Anthrax is a serious, often fatal zoonotic disease of wild and domestic mammals caused by the spore-forming bacterium [[Bacillus anthracis]]. The disease occurs worldwide and often in outbreaks. ''B. anthracis'' spores are highly resistant and can survive in the environment for many years. In herbivores, the disease commonly presents as a peracute onset septicaemia with a high mortality rate. In dogs, humans, horses and pigs the onset is less acute. |
| + | There are three main forms of the disease; gastrointestinal, pulmonary or cutaneous. | ||
===Clinical signs==== | ===Clinical signs==== | ||
| − | ==== | + | ====Ruminants and horses==== |
| − | + | * Fatal peracute septicaemia | |
| − | *** | + | * Sudden death |
| − | * | + | * Acute onset pyrexia |
| + | * Depression | ||
| + | * Neurological signs such as staggering or trembling | ||
| + | |||
| + | In addition to the above signs, subcutaneous oedematous swellings may be observed in horses. | ||
| + | |||
| + | congested mucous membranes and petechiae before death | ||
***Abortion, subcutaneous oedema and dysentry in animals surviving more that one day | ***Abortion, subcutaneous oedema and dysentry in animals surviving more that one day | ||
===Pigs=== | ===Pigs=== | ||
| − | + | Pigs are relatively resistant to anthrax and the disease often has a more chronic course affecting the oropharyngeal region. The disease often begins as an oedematous cellulitis of the the neck, head and regional lymph nodes. This may cause death by asphyxia. | |
| + | |||
***Intestinal form with high mortality - dysentry due to haemorrhagic enteric lesions | ***Intestinal form with high mortality - dysentry due to haemorrhagic enteric lesions | ||
***[[Peritonitis#In pigs|Peritonitis]] | ***[[Peritonitis#In pigs|Peritonitis]] | ||
Revision as of 20:05, 27 July 2010
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This article is still under construction. |
Description
Anthrax is a serious, often fatal zoonotic disease of wild and domestic mammals caused by the spore-forming bacterium Bacillus anthracis. The disease occurs worldwide and often in outbreaks. B. anthracis spores are highly resistant and can survive in the environment for many years. In herbivores, the disease commonly presents as a peracute onset septicaemia with a high mortality rate. In dogs, humans, horses and pigs the onset is less acute. There are three main forms of the disease; gastrointestinal, pulmonary or cutaneous.
Clinical signs=
Ruminants and horses
- Fatal peracute septicaemia
- Sudden death
- Acute onset pyrexia
- Depression
- Neurological signs such as staggering or trembling
In addition to the above signs, subcutaneous oedematous swellings may be observed in horses.
congested mucous membranes and petechiae before death
- Abortion, subcutaneous oedema and dysentry in animals surviving more that one day
Pigs
Pigs are relatively resistant to anthrax and the disease often has a more chronic course affecting the oropharyngeal region. The disease often begins as an oedematous cellulitis of the the neck, head and regional lymph nodes. This may cause death by asphyxia.
- Intestinal form with high mortality - dysentry due to haemorrhagic enteric lesions
- Peritonitis
Horses
- Subacute anthrax with subcutaneous oedema of thorax, abdomen and legs following entrance of spores into abrasions
- Septicaemia with colic and dysentry due to haemorrhagic enteritis from ingestion of spores; ecchymoses and splenomegaly
Dogs
- Rarely affected, but similar disease to that found in pigs
Humans
- Cutaneous anthrax - localised lesion from entrance into abrasion which can cause septicaemia
- Pulmonary anthrax - inhalation of spores
- Intestinal anthrax - ingestion of infective material
- Diagnosis:
- Post mortem: bloat, incomplete rigor mortis, ecchymoses, oedema, dark unclotted blood from orifices, blooy fluid in body cavities, splenomegaly
- Blood smear from an ear or tail vein of ruminants, or peritoneal fluid from pigs stained with polychrome methylene blue
- Chains of square-ended blue rods surrounded by mauve capsules
- Culture on blood and MacConkey agar (no growth on MacConkey)
- Biochemical tests
- Treatment:
- High doses of penicillin G or oxytetracylcine
- Control:
- Report suspected cases - notifiable
- Spores destroyed by sterilisation
- Endemic regions:
- Live Sterne spore vaccine which produces toxin but has no capsule, therefore is non-pathogenic; stimulates protective antibody
- Chemoprophylaxis with long-acting penicillin
- Non-endemic regions after an outbreak:
- Movement restrictions
- Footbath with sporicidal disinfectant
- Fumigate buildings with formaldehyde
- Dispose carcases and contaminated material
- Isolate in-contact animals