Meningitis
What is it?
Pig meningitis can be caused by the Streptococcus suis (Strep. suis) bacterium, which can infect people in whom meningitis often develops. It is commonly found in the tonsils and nasal cavities of healthy pigs and is endemic in most countries with a substantial pig industry, including the UK. There are at least 35 different types of Strep. suis. Two have been implicated in human infections.
History
Streptococcus suis has been a recognised zoonosis infectious disease that can be transmitted from animals to humans since 1968.
Symptoms in animals
Meningitis is most common in 4-8 week old pigs. Typical symptoms include involuntary eye movement, convulsions, paddling, shivering, signs of pain/discomfort, raised hair and grinding teeth.
Source
The bacteria can be spread by direct and indirect contact and can cause disease when too many pigs are crowded together. Pigs may spread infection without showing any symptoms.Separate studies in 2001 and 2004 concluded that around half of the British pig herd was carrying Strep. suis.
Routes of transmission
Human infection is usually through close contact with infected pigs or with raw or under cooked pig meat, and is thought to occur through cuts or abrasions on the skin when handling infected pig carcasses. Just two or three human cases of Strep. suis are reported each year but it is a recognised occupational hazard to veterinary surgeons, farmers and meat industry workers. The last fatal case of pig linked meningitis in the UK occurred in a farm worker in 1999. In 2005, a human disease outbreak in China caused by a strain of Strep. suis raised concern among the World Health Organization and UN Food and Agriculture Organization. Thirty seven farmers who died displayed symptoms - bleeding under the skin - that had previously been unheard of with the disease. This outbreak coincided with one in the local pig populations.