SUDS disease, a term sometimes used to describe sudden, unexplained deaths in animals, often refers to a specific bacterial infection known as erysipelas. This condition primarily affects livestock, especially swine, and is caused by a particular bacterium. Erysipelas has historically impacted animal health due to its economic effects and potential to spread within herds.
Understanding SUDS Disease
Erysipelas is an infectious condition caused by the bacterium Erysipelothrix rhusiopathiae. This Gram-positive, rod-shaped bacterium is found worldwide and can manifest in acute, subacute, and chronic forms. It has been recognized since the late 1880s and continues to impact animal agriculture globally.
The bacterium Erysipelothrix rhusiopathiae can survive for extended periods in the environment, including soil and marine locations. It can persist in pig feces for approximately one to five months.
How It Spreads and Who It Affects
Erysipelothrix rhusiopathiae spreads primarily through ingesting contaminated feed, water, or feces. The bacteria are shed in the feces, urine, and oronasal secretions of infected animals, including healthy carriers. Transmission can also occur through skin abrasions.
Pigs are the most commonly affected species, with up to 50% of healthy pigs potentially carrying the bacterium in their tonsils without showing disease signs. These asymptomatic carriers are a significant source of infection for other animals. Pigs between three and twelve months of age and pregnant sows are particularly susceptible.
The bacterium has been isolated from a wide range of animals, including turkeys, sheep, cattle, horses, dogs, cats, mice, rats, and various wild birds and mammals. Fish, both freshwater and saltwater species, can also harbor the bacteria. Outbreaks in poultry, especially turkeys and laying hens, are also reported, with increasing cases in cageless production systems.
Identifying the Symptoms
Symptoms of erysipelas vary by affected species and disease form. In pigs, the acute form often presents with sudden death, high fever (104-108°F), depression, and anorexia. A distinctive symptom is diamond-shaped skin lesions, which are raised, red to purple, and firm. These lesions, often easier to feel than see in early stages, may turn black due to tissue death and typically heal within 7-10 days.
Pigs with acute erysipelas may also exhibit stiffness, lameness, or a reluctance to move, often walking stiffly on their toes. Respiratory distress can occur, and pregnant sows may experience abortions due to the fever. In some cases, especially in younger pigs, there may be cyanosis or a bluish discoloration of the ears, snout, and extremities.
The subacute form in pigs presents with similar but milder signs, with fewer or less severe skin lesions and a mild fever. Chronic erysipelas, which can follow acute or subacute cases, is most commonly characterized by arthritis, leading to persistent lameness. Infection of the heart valves (endocarditis) can also occur, causing heart failure and potentially sudden death. In turkeys, symptoms include cyanotic skin lesions, often appearing as a “blue comb,” muscle hemorrhages, and sudden deaths. Sheep, particularly lambs over one month old, commonly show arthritis.
Confirming the Diagnosis and Treatment Options
Diagnosis of erysipelas involves clinical observations and laboratory confirmation. The presence of characteristic diamond-shaped skin lesions in pigs is highly indicative, though other diseases can present similarly. In cases of sudden death or severe illness, a high fever, stiff gait, and reluctance to move are strong indicators.
Post-mortem examination can reveal an enlarged spleen, congested lymph nodes, and petechial hemorrhages on organs. Joint lesions, including arthritis and ulceration of articular cartilages, are common in chronic cases. Definitive diagnosis relies on laboratory confirmation through bacterial culture of fresh tissues, fluids, or blood. PCR testing on oral fluids, serum, or tissue samples provides a rapid and reliable diagnostic method. However, detecting the bacteria in healthy carriers (30-50% of pigs) means clinical signs must accompany a positive test for a conclusive diagnosis.
Treatment for erysipelas, particularly in acute cases, is highly effective with antibiotics. Penicillin is the drug of choice due to the bacterium’s susceptibility to beta-lactam antimicrobials. Early administration of penicillin usually leads to dramatic improvement within 24-36 hours. While acute cases respond well, there is no practical treatment for chronic forms of the disease, and such animals may need to be culled. Supportive care, such as fluid and electrolyte replacement, may also be beneficial.
Prevention and Human Health
Preventing erysipelas outbreaks relies on vaccination, biosecurity, and sound animal husbandry. Vaccination programs are highly effective, especially for swine, in controlling disease and reducing losses. Both injectable bacterins and live attenuated vaccines are available and provide extended immunity. Young breeding stock should be vaccinated twice before entering the herd, and sows typically receive booster vaccinations before farrowing or every six months.
Biosecurity measures, including strict sanitation and hygiene, are important in preventing the spread of Erysipelothrix rhusiopathiae. Regular cleaning and disinfection of barns, along with proper disposal of feces, help reduce environmental contamination. Limiting exposure to potential carriers, such as wild mammals, birds, and surface water runoff, also helps control the disease. Managing stress factors like overcrowding, mixing pigs after weaning, and sudden temperature changes can help prevent disease triggers.
Erysipelothrix rhusiopathiae has zoonotic potential, meaning it can be transmitted from animals to humans. Human infection, known as erysipeloid, typically occurs through direct contact with infected animals, their products, or wastes, often through skin abrasions or cuts. This is primarily an occupational hazard for individuals working with animals, such as farmers, veterinarians, butchers, and slaughterhouse workers.
Erysipeloid usually manifests as localized cutaneous lesions, which are painful, red, and swollen, often on the hands. While usually mild, severe cases can lead to systemic complications like septicemia or endocarditis, though these are rare. Protective measures, including wearing gloves and maintaining good personal hygiene, are important for individuals at risk of exposure.