Population-Based Study of Streptococcus suis Infection in Humans in Phayao Province in Northern Thailand

Abstract

Background Streptococcus suis infection in humans has received increasing worldwide recognition.Methods and FindingsA prospective study of S. suis infection in humans was conducted in Phayao Province in northern Thailand to determine the incidence and the risk behaviors of the disease in this region in 2010. Thirty-one cases were confirmed. The case fatality rate was 16.1%, and the estimated incidence rate was 6.2 per 100,000 in the general population. The peak incidence occurred in May. The median age of the patients was 53 years and 64.5% were men. Consumption of raw pork products was confirmed in 22 cases and the median incubation period (range) was 2 days (0–11) after consumption of raw pork products. Isolates from 31 patients were confirmed as serotype 2 in 23 patients (74.2%) and serotype 14 in eight patients (25.8%). The major sequence types (STs) were ST1 (n = 20) for serotype 2 and ST105 (n = 8) for serotype 14. The epidemiological analysis suggested three possible clusters, which included 17 cases. In the largest possible cluster of 10 cases in Chiang Kham and its neighboring districts in May, the source of infection in four cases was identified as a raw pork dish served at the same restaurant in this district. Microbiological analysis confirmed that three of four cases associated with consumption of raw pork at this restaurant were attributable to an identical strain of serotype 2 with ST1 and pulsotype A2.ConclusionsOur data suggest a high incidence rate of S. suis infection in the general population in Phayao Province in 2010 and confirm a cluster of three cases in 31 human cases. Food safety control should be strengthened especially for raw pork products in northern Thailand.

Antimicrobial Susceptibility, Tetracycline and Erythromycin Resistance Genes, and Multilocus Sequence Typing of <i>Streptococcus suis</i> Isolates from Diseased Pigs in China

“…We showed that most S. suis serotype 2 strains from diseased pigs in China belong to ST1 and ST7, which differed from another study performed in North America, in which most S. suis serotype 2 strains belonged to ST28 and ST25, and only a small percentage (5%) of isolates were assigned to ST1 [8]. ST1 was the major ST identified and has resulted in the deaths of 3 out of 20 patients in northern Thailand [21]. ST7 caused the human STSS outbreaks in the Sichuan and Jiangsu provinces of China [26].…”

Development of loop-mediated isothermal amplification to detect Streptococcus suis and its application to retail pork meat in Japan

“…suis belonging to the ST1 complex has attracted considerable public attention as a clonal group that may have a higher degree of virulence for humans than the other clonal groups (King et al, 2002), whereas most of the other human clinical isolates were classified into ST25, ST28, ST101, ST102, ST103, or ST104 (Chang et al, 2006;Takamatsu et al, 2008;Takeuchi et al, 2012), which were grouped into the ST25 complex (formerly the ST27 complex). Therefore, these findings suggest that the ST25 complex is another clonal group that needs to be considered due to its importance in human infection.…”

Rapid Visual Detection of Highly Pathogenic Streptococcus suis Serotype 2 Isolates by Use of Loop-Mediated Isothermal Amplification

“…However, S. suis infection has become widespread in large-scale pig farms, causing huge economic losses and threatening public health due to its rapid spread and high mortality rates (28). So far, S. suis 2 has caused Ͼ95% of reported human S. suis infections (29) and it is a major pathogen that causes life-threatening bacterial meningitis in developing countries (30,31). In recent years, several virulence-associated biomarkers, such as CPS, muramidase-released protein, and extracellular factor, have been used for the detection of S. suis 2 infection.…”