Human Streptococcus suis outbreak in Phayao province, Thailand, 2007
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Date
2010-06-02
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Outbreak, Surveillance and Investigation Reports
Abstract
Background: On May 1st, 2007, the Bureau of Epidemiology received a report of a cluster of five patients with bacteremia and meningitis of unknown cause, including two deaths, from Hospital A. An investigation was performed to determine the etiology and source of the outbreak, and to recommend preventive measures. Methods: A suspected case-patient was defined as a person in village 4, 5 or 9 of Thung Kluai subdistrict, Phusang district, Phayao province who had fever and at least one of following signs or symptoms of severe myalgia, severe headache, nausea/vomiting, diarrhea, arthalgia, ecchymosis, neck stiffness, seizure, alteration of consciousness between April 12th-May11th, 2007. A confirmed case-patient was suspected case that subsequently had laboratory confirmation of S. suis. Specimens from case-patients were tested by culture, biochemical test and PCR. An environmental survey was conducted around the areas of epidemiological interest, pig domestication and food preparation processes. We conducted a case-control study to determine risk factors for persons who become ill with S.suis infection. Controls were chosen from the people in those villages by simple random sampling. Results: In total, 50 suspected case-patients were identified. The male to female ratio was 1.3: 1, median age was 49 years (range: 10-77). Common clinical signs and symptoms included severe myalgia (84%) and severe headache (58%). Initial cases developed symptoms on April 25th, 2007. The mean time from ate implicated item to onset of symptom was 6 days (range: 1-9). We found ten of them had positive from hemoculture and specified S. suis serotype 2 based on biochemical test and PCR. Twenty six of suspected case-patients were positive from serological test. Eating raw pig blood was a statistically significant risk factor (OR=24.8; 95%CI 1.46 - 423.53). Overall case fatality rate was 6%. Conclusion/Interventions: This was the first large scale outbreak of S. suis serotype 2 infections reported in Thailand. Risk factors for this outbreak included eating raw pig blood. Appropriate food preparation was promoted. Enhanced S.suis case surveillance was implemented.
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Outbreak, Surveillance and Investigation Reports; Issue 1, Vol 1, 2008; 4-7