Erysipelas is caused by a bacterium called Erysipelothix Rhusiopathiae and can affect stock 6 weeks of age and older. Infection is transmitted between pigs by contact with infected saliva, urine, faeces and also nasal discharges. Birds and small mammals can act as a reservoir for infection.
Erysipelas survives for a long time in the environment, surviving in soil or muck for 6 months or longer. It is also relatively resistant to drying, which can make environmental control difficult.
There are different forms of the clinical signs seen with this disease.
In the Acute, very sudden onset, affected pigs have a high temperature and decreased appetite. They can be dull and reluctant to move, the pigs skin and or ears may show red to dark purple patches and usually follows 12 – 48 hours late.
The skin can have raised areas that are warm to the touch, and it is these that go on to develop into the classic ‘diamond’ skin lesions. They usually appear 24 – 48 hours after the onset of clinical signs and are more easily seen on white pigs.
As infection with Erysipelas causes an increased temperature, affected sows can abort and boars become sub – fertile for up to 6 – 8 weeks due to damaged sperm.
Erysipelas can also cause chronic long term disease, it can cause inflammation of the valves in the heart that ensure blood flow through the heart. When this is extreme, sudden death can result as the pig goes into congestive heart failure. Prior to death, the pig can appear to have pneumonia due to the fluid build up on the lungs as the heart malfunctions.
Erysipelas bacteria can also be found in the joints that leads to arthritis, and should always be considered as a cause of lameness in finishing pigs. Lameness or stiffness may be seen on farm and your abattoir may report increased numbers of joint condemnations.
Erysipelas can be treated effectively in the acute sudden stage of the disease, it is very sensitive to penicillin based antibiotics and these can be administered through individual injection, group water or feed medication depending on the clinical situation on farm. Chronic lesions in the heart or joints are less likely to respond to antibiotics.
Erysipelas is zoonotic, which means it can infect humans as well. To reduce the risk of human infection from infected carcases in the slaughter house , it is a legal requirement that pigs showing clinical signs of acute Erysipelas infection with a fever cannot be sent to slaughter.
To reduce potential fertility problems in the adult herd it is recommended to vaccinate breeding stock. Animals are susceptible to the disease from 6 weeks of age and gilts should complete their primary course, usually as 2 separate injections. to maintain good immunity they should receive a booster every 6 months, this also applies to breeding boars.