Diseases

Learn More About a Disease

Edema disease

Edema disease, or Escherichia coli enterotoxemia, is a deadly infectious pathology that affects pig farms around the world. It appears mainly in piglets within the first two weeks after weaning. It is due to the proliferation of the E. coli bacteria that produce Stx2e shiga toxins (STEC), also known as verocytotoxin-producing E.coli (VTEC). This colibacillus (intestinal bacterium) causes diarrhea or sudden death in pigs. Escherichia coli (E. coli) is present in the digestive tracts of animals. Some strains of E. coli, particularly VTEC, cause diarrhea and a variety of diseases in animals. VTEC have fimbriae or pili (specialized structures) that allow the bacillus to attach itself to the intestinal wall, where it produces toxins that trigger the secretion of liquids and electrolytes into the intestinal lumen, causing diarrhea, dehydration and acidosis. The disease can be triggered by the misuse of antibiotics, and such stress factors as a change in environment or feed, weaning, or cohabitation with different groups of animals.4

Clinical Signs +

VTEC can cause edema disease in piglets, usually after weaning and when they are between 4 and 12 weeks of age.  Onset of the disease is sudden, the first sign being a lack of coordination of the hind legs, and progresses to total paralysis and death. In its less observable manifestations, the face and eyelids may also become swollen.  Even if the disease does not seem to spread, it affects pigs with the best growth rates.4

Transmission +

In general, the infection is transmitted through the fecal-oral route. Because coliforms are frequently found in the feces of pigs, pathogenic E. coli ingested in the environment develop in the intestine, furthered by disturbances often linked to the piglet's ability to digest certain foods and nutrients.2

Diagnosis +

Confirmation of diagnosis is by histological observation of a villi culture, i.e. the isolation of pili antigens through immunofluorescence or other immunological techniques performed on intestinal scrapings.

Enterotoxigenic strains of an Escherichia coli being the cause of the disease, the involvement of other agents, such as viruses or coccidia, should be considered.

Diagnosis is generally confirmed through animal autopsy. Hemorrhages of the wall of the small intestine, or a mesenteric or mesocolonic edema may be observed.3

Treatment +

Because the onset of disease is sudden and its course rapid, treatment is often ineffective. Therapeutic measures include rapid treatment with appropriate antibiotics and restoring fluid and electrolyte balances in pigs less severely affected.

Consult your veterinarian before administering antibiotics and vaccines to animals. Your veterinarian is the best source of recommendations that are truly adapted to your farm.

Prevention +

Disease prevention requires reducing contributory factors such as humidity and cold. Hygiene measures and general cleanliness reduce VTEC infections to a minimum. Vaccination of pregnant sows is recommended. Vaccination of piglets is also possible around weaning time. 

REFERENCES:

1 Ontario Ministry of Agriculture - Animal Health

2 Public Health Agency of Canada

3 Edema disease - Iowa State University-College of Veterinary Medecine

4 The Merck Veterinary Manual, Third Edition

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