Spread of the disease
Edema disease (Engl. Edema Disease, ED) is a lethal infectious disease, which is seen in pig production throughout the world. It primarily occurs in piglets during the first two weeks after weaning. It is caused by a proliferation of Shigatoxin-producing E.coli bacteria (STEC), which is known as Verotoxin. A German study to differentiate pathogenic E. coli bacteria in weaning pigs found STEC in 34% of cases (Sting and Stermann 2008).
Synlab.vet GmbH in Leipzig analysed the samples received in 2011/2012 and, with the aid of PCR, found E.coli strains, which can produce Shigatoxin Stx2e, in 37 % of cases.
Edema disease usually occurs within the first two weeks after weaning. The heavier and best-developed animals within a group are especially affected. Older animals only develop the disease in limited cases.
The clinical picture of edema disease is triggered by a proliferation of STEC in the intestine followed by Shigatoxin Stx2e synthesis.
This is made more favourable by
Shigatoxin is one of the most potent, naturally occurring poisons. It destroys the very fine blood vessels, the capillaries, and causes fluid accumulation in the tissue. It particularly affects the intestines, hypodermis and brain. For this reason animals that do not suddenly die of a peracute incidence of the disease, suffer edema of the eyelids, bridge of the nose and intestines. The animals also demonstrate fits and convulsions, paralysis and lying on the side paddling as a result of neurological deficits. Diarrhoea and dehydration are also observed if other enterotoxins (LT and ST) are produced in addition to Shigatoxin. Adistinctive sign of laryngeal edema is the unusual, high-pitched squeal of the pigs. It is a matter of the dose of the poison as to whether the pig dies within hours or remains to be reared as a runt lacking in performance behind its pen mates.