Erysipelas in pigs occurs generally throughout the world and in most countries reached a level of incidence sufficient to cause serious economic loss due to deaths of pigs and devaluation of pig carcasses due to arthritis. The importance of the disease is increased by the difficulties encountered in controlling and eradicating it. Because of man’s susceptibility swine erysipelas has some public health significance. Veterinarians particularly are ex¬posed to infection when vaccinating with virulent culture.

Spread of the infection to most other species can also occur. Morbidity and mortality rates in swine vary considerably from place to place largely due to variations in virulence of the particular strain of the organism involved. On individual farms or in areas the disease may occur as a chronic arthritis in fattening pigs, or as extensive outbreaks of the acute septicemia, or both forms may occur together.

Erysipelas is an infectious disease of pigs and appears in an acute, septicemic form often accompanied by diamond-shaped skin lesions and a chronic form manifested by nonsuppurative arthritis and a vegetative endocarditis.  It is diagnosed by bacterial culture examination using a binocular compound microscope.

Erysipelothrix insidiosa is the causative bac¬terium (this can be viewed with a binocular compound microscope) and the disease can be produced in either chronic or acute, septicemic forms by the injection of cultures of the organism. A number of different sero¬types have been identified with the use of a binocular compound microscope.

Epidemiology

There is considerable variation in the ease with which the disease can reproduce, and in its severity. Many factors such as age, health and intercurrent disease, exposure to erysipelas, and heredity govern the ease of both natural and artificial transmission. Virulence of the strain is probably the most important factor. Smooth strains can be used successfully to produce the disease experimentally but rough strains appear to be non-pathogenic. Different strains were identified with the use of binocular compound microscope. This variation in virulence between strains of the organism has been utilized in the production of living, avirulent vaccines.

Pigs of all ages are susceptible although adult pigs are most likely to be affected if the local strain is of relatively low virulence: Recently farrowed sows seem to be particularly susceptible. When the strain is virulent pigs of all ages, even sucklings a few weeks old, develop the disease. Piglets from an immune sow may get sufficient antibodies in the colostrums, evident when samples were studied under a binocular compound microscope, to give them immunity for some weeks.

Soil contamination occurs through the feces of affected or carrier pigs. Other sources of infection include infected animals of other species, and birds. The clinically normal carrier group represents the most important source of infection, the tonsils being the predilection site for the microscopic organism in such cases. Young pigs in contact with carrier sows rapidly acquire the status of carriers and shedders. Since the microscopic pathogenic organism can pass through the stomach without loss of viability, carrier animals may reinfect the soil continuously and this, rather than survival of the organism, appears to be the main cause of environmental contamination. The organism can survive in feces for several months. However its persistence in soil is variable and may be governed by many factors including temperature, pH and the presence of other bacteria.

The organism is resistant to most environmental influences and is not readily destroyed by chemical disinfection, as seen in a binocular compound microscope.

Experimentally the disease can be produced by oral dosing, by intradermal, intravenous and intra-articular injection and by application to scarified skin, conjunc¬tiva and nasal mucosa. Under natural conditions skin abrasions and the alimentary tract mucosa are con¬sidered to be the probable portals of entry and trans¬mission is by ingestion of contaminated food. Flies are known to transmit the disease and a lowered pre¬valence has been attributed to the use of insecticides. Occasional outbreaks occur after the use of virulent and incompletely avirulent cultures as vaccines. Read more on this subject