Streptococcus suis is a streptococcal bacterium which has a distinctive boat shape, possesses a capsule to resist phagocytosis (digestion by white cells in the body) and a toxin. S. suis is sensitive to a wide range of antimicrobials and farm disinfectants but survives 512 days on the tonsils in carrier animals and 25 days at 9°C in dust. S. suis infects pigs at or shortly after birth from the sow or by aerosol or contact within 5-25 days of mixing with carrier animals. It multiplies in the tonsillar crypts, is taken up by white blood cells and is distributed in the blood to the brain and joints. It can cause septicaemia within a few hours which may kill the animal or cause meningitis which is frequently fatal. Arthritis also occurs.
Serotype 1 causes disease in piglets of 10-14 days of age. Affected animals cease to thrive, become rough-coated, develop fever (40.6-41.1°C, 105-106°F) and may die. Enlarged, hot, painful swollen joints develop later or animals become stiff, bind or show muscular tremors ending in ataxia or death. Sudden death may occur in endocarditis due to streptococcal infection. Typically, up to two thirds of the litter develops some form of the disease. Serotype 2 causes disease in pigs aged 3-12 weeks or more with an incubation period of 24 hours to 2 weeks. Outbreaks often begin with the death of a pig in a good condition. Fever of 40.6-41.7°C, 105-107°F and flushing of the skin may occur in live pigs. Nervous signs such as incoordination, tremor, paralysis, paddling, opisthotonus and tetanic spasms develop in that order. Death can occur within 4 hours of the onset of the clinical signs. Animals developing meningitis have a glassy stare, flushed skin and unsteady gait. Head tilt is sometimes present. Arthritis may occur in younger pigs and occasionally in gilts and sows. Bronchopneumonia may occur. Mortality varies from 1-50% in any batch of pigs and in herds with enzootic infection may be 0.5% with 1% morbidity.
• Increased feed cost
• Less weight gain