Herd Health: What is Streptococcus suis?

Tuesday, December 2, 2008

by BETH YOUNG and CATE DEWEY

Streptococcus suis is a bacterium commonly found in pigs worldwide.  Many piglets become infected with it during or shortly after birth. The bacteria can be found in the nose and tonsils of many pigs, even those that don't become sick. People often refer to it as "strep" or "strep suis."

What happens to pigs?
The disease usually affects nursing or recently weaned pigs, but pigs of any age can become ill. The most common signs of this disease are found in pigs which develop meningitis (brain infection). These pigs are often found lying on their sides and paddling. It can also cause unsteadiness, head tilting, tremors and seizures. The disease progresses rapidly and some pigs die so quickly that signs of illness are not noticed. The bacteria can also cause pneumonia, arthritis and blood poisoning.

What happens to people?
Human infection with Streptococcus suis is extremely rare, particularly in Canada. Abattoir workers are the most susceptible, but others who work closely with pigs, such as farmers and veterinarians, can also be affected.

Infection occurs when the bacteria enter the body through skin wounds during contact with infected pigs or pork. Symptoms in infected people can include fever, nausea and vomiting, pneumonia, arthritis, meningitis, septicemia (blood infection), coma and, occasionally, death. Permanent deafness is common in people who have recovered from the infection.

What can be done to prevent it from spreading from pigs to people?
Any cuts or scrapes incurred when working with pigs or in a pig barn should be thoroughly cleaned and covered with a bandage. Gloves should be worn when treating or handling pigs that are suspected of being sick with Streptococcus suis. Hand washing after handling these pigs is also important.

Any pigs that have died from Streptococcus suis infection should quickly be disposed of in an appropriate manner, so people cannot come in contact with them. Wearing gloves when disposing of dead pigs and washing hands when finished will also help prevent human infection. Ensuring that pigs which are sick or have died are not slaughtered for human consumption is extremely important. BP

Beth Young is a post-doctoral researcher and Cate Dewey is a professor in the Department of Population Medicine, Ontario Veterinary College, University of Guelph