Streptococcus suis infection: An emerging/reemerging challenge of bacterial infectious diseases?

Feng, Youjun; Zhang, Huimin; Wu, Zuowei; Wang, Shihua; Cao, Min; Hu, Dan; Wang, Changjun

Accumulated epidemiological data suggests that over 85% of total cases have occurred in Asian countries. 2 The cases of human SS2 infections in the mainland of China and Vietnam are comparable. 2, 8, 16 Relative to the above 2 countries, the human cases clinically infected by S. suis are second. 6, 14, 87 Of being noteworthy, SS2 has been recognized as a pathogen with the mostly-relevance to human bacterial meningitis in southern Vietnam. 16 In Hongkong, the specialized administrative region of China, the first human case of S. suis infection was recorded in 1983, 78, 80 and the accumulated number of S. suis infections were estimated to be about 60 cases. 75, 78 In particular, two big outbreaks of human SS2 infections in China (1998 and 2005) seriously challenged public health. 9, 18 In the 1998 epidemic, 14 out of 25 SS2infected persons died along with an estimated 80 000 pigs. 18 In the 2005 epidemic, totally 215 patients had SS2 infections, 38 of which are dead. A similar scenario was also observed when more than 600 pigs were demonstrated to be infected by SS2. 9, 18 The causative agents of the both epidemics were subsequently determined to be highly invasive clones of strong virulent SS2 strain that seemed to have acquired a new pathogenicity island 89K. 8, 23, 94 Additionally, sporadic human meningitis cases caused by SS2 infections were observed in three other cities of China (Shenzhen City, Chongqing City, and Nanjing City) in 2007, 4, 95 implying that the situation of SS2 infection in China is complicated. This could be due to variants of S. suis 2 identified in subsequent investigations. It might be of much interest to unveil the possible evolutionary relationship of the Chinese epidemic strain with those of the neighboring country like Vietnam through comparative genomics.