The pathogen Streptococcus suis (S. suis) that causes infections in pigs is increasingly being seen in humans in some parts of the world. The infection is acquired through exposure to contaminated pigs, carcasses, or pig meat and organs, so occurs most frequently in farm and slaughterhouse workers, as well as veterinarians. But cases also can occur in those who consume raw pork products.
A predominance of S. suis cases have occurred in Southeast Asia, where there is a high density of pigs, with as many as 436 cases reported in Thailand this year (through Sept. 25), and 9 people dying from the infection. In a cross-sectional study, live pigs from 111 farms across Chiang Mai, Thailand were sampled to determine prevalence of S. suis, with results showing 18.2% (138/760) of tonsil swab samples and 54.1% (60/111) of pig farms to be positive.
The lower prevalence rates found in Europe and North America may be due to less virulent strains or underdiagnosis or misdiagnosis along with the good hygiene conditions and prevention strategies conducted during pork processing operations (e.g., wearing gloves). However, more study and research is needed to ensure understanding and enable more effective response to the occurrence of S. suis infections, especially in southeast Asia.
Although cases do most often occur in those working with pigs, travelers should be aware that dietary habits in some countries may pose a risk for infectious diseases, including S. suis infection. Infections can typically be successfully treated with antibiotics, but prompt medical attention is needed.
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