Streptococcus suis infection is a re-emerging zoonotic disease reported worldwide. This study is aimed to describe the clinical features and determine the risk factors for mortality of this life-threatening disease.

A retrospective cohort study was conducted among patients diagnosed with culture-confirmed S. suis infection in a tertiary-care hospital in Northern Thailand during 2005–2007. Risk factors for mortality were determined by Cox's regression analysis.

There were 66 patients with a mean age of 52.9 years; 68% were males. The most common risk of S. suis infection was eating under-cooked pork (59%). Clinical presentations included acute meningitis (52%), sepsis (27%), septic shock (12%), endocarditis (8%), and septic arthritis (1%). Hearing loss was observed in 35% and was associated with meningitis. The overall mortality rate was 17%; 11% occurred in 24h. Cox's regression revealed that septic shock (p=0.014) and elevated alanine transaminase (ALT, p=0.013) were risk factors for mortality.

S. suis infection is common in Northern Thailand, where people often eat raw pork, and commonly presents with acute meningitis or sepsis. The mortality rate is high. The risk factors for mortality are septic shock and elevated ALT. Awareness of this disease and public education are essentially needed.