ETIOLOGY AND PATHOGENY: PART 1

Erysipelas or 'Swine Erysipelas' is an infectious disease caused by Erysipelothrix rhusiopathiae. This disease is characterized by cutaneous or septicemic pictures, and can also produce arthritis or valve endocarditis when it is chronic.

Erysipelothrix rhusiopathiae has 26 serotypes, and 1 and 2 affect pigs. This agent has also been isolated from sheep, rodents and birds, and in slaughterhouses are found in a high percentage of animals that were asymptomatic.

In pigs, most clinical infections appear in the transitional – fattening stage, when maternal antibodies decrease acutely or are chronic in adult pigs and in this case there will be no septicemia.

The disease is uncommon in pigs 8-12 weeks of age, thanks to the protection provided by maternal antibodies through colostrum. Therefore, growing pigs, first-time sows and unvaccinated sows are more susceptible to the disease.

The transmission of the disease can be by oral or percutaneous route from the environment or from carriers of the disease.

Subsequently, it passes to the tonsils or lymph nodes and the infection reaches the blood, producing a septicemic process. At this time, the animal will suffer fever, dejection and discomfort. It will also produce an inflammatory reaction that leads to the formation of hyaline thrombi, which occlude the peripheral vessels, causing the characteristic diamond-shaped skin lesions. From this point, the infection can also become chronic, at which point the dermal form will normally disappear. In the chronic form, there is arthritis, which can manifest as a slight limp until there is a total lack of movement of the joint. Another frequent lesion is proliferative endocarditis, which is found mainly at the valve level, and is caused by the previous septicemic process. The mitral valve is usually the most affected, eventually occluding communication with the pulmonary veins or the aorta. This stenosis causes different clinical signs such as dyspnea, tachycardia, stress cyanosis and weight loss.

Finally, a necrotic dermatitis can also be seen less frequently, which can affect the ears, tail, distal parts of the extremities, head and back.