Classification: ICD-9 A41.09; ICD-10 A40.8
Syndromes and synonyms: None.
Agent: Streptococcus suis, a Gram-positive alpha-hemolytic bacterium, with 35 serotypes based on capsular polysaccharide antigens. The predominant one causing human disease is serotype 2.
Reservoir: Pigs; occasionally found in wild boar, horses, dogs, cats, and birds. Asymptomatic pigs typically carry the bacteria in their tonsils.
Transmission: Through wounds on the skin, including minor abrasions. Infection via ingestion of contaminated improperly cooked pork products. No human-to-human transmission.
Cycle: Pig-to-pig, with occasional spill-over to humans.
Incubation period: From a few hours up to 3 days.
Clinical findings: Fever and signs of meningitis (headache, vomiting, neck stiffness, intolerance of light, and decreased level of consciousness). Hearing loss, generally permanent, in around 50% of those infected. Arthritis, pneumonia, and fatal toxic shock syndrome are possible complications.