An outbreak investigation of Streptococcus suis infection, Maewang District, Chiang Mai Province, Thailand, June 2017

Abstract

Background: On 2 June 2017, three suspected Streptococcus suis infection patients were notified to SRRT Santopong, Chiang Mai Province. We investigated this event to confirm the diagnosis, confirm the outbreak, describe the epidemiology of the outbreak and implement control measures.
Methods: We conducted the descriptive study by reviewing medical records, interviewing patients at Sanpatong hospital and conducted the active case finding. The case definition was people who lived in Donpao Sub-district, Maewang District, Chiang Mai Province and had history of contact with pigs, ate raw pork or ate raw blood of pigs between 26 May – 7 June 2017. Environmental study were conducted by interviewing pork butcher’s shops, pig slaughterhouse and pig farms and walking through survey for the surroundings. We collected some blood and cerebrospinal fluid for bacteria culture and PCR serotyping for S. suis.
Results: Three cases were confirmed S. suis outbreak. The attack rate was 60% from five exposure of eating raw minced beef and pork. All of patients had history of daily alcohol consumptions. Clinical presentations of all patients were fever, alteration of consciousness, confusion and myalgia. Environmental study showed the cases ate raw pork, which raised within the case’s house. All of pork butcher’s shops, pig slaughterhouse and pig farms had good standard. Laboratory study showed 3/3 blood/cerebrospinal fluid culture had Streptococcus suis and 2/2 multiplex PCR showed serotype 2.
Discussion and Conclusions: We confirmed the outbreak of Streptococcus suis infection at Maewang District, Chiang Mai Province between 26 May – 7 June 2017 which had 3 confirmed cases and one dead. Attack rate was 60 percent. This event was point common source from eating raw pork. The pathogen of this outbreak was Streptococcus suis serotype 2.