Key surveillance for typhoid/paratyphoid fever in China, 2012

Objective To understand the predominant serotypes, the change in drug resistance of Salmonella typhi and Salmonella paratyphi and the change of related pulsed-field gel electrophoresis (PFGE) pattern in surveillance areas in the mainland of China. Methods Descriptive epidemiological analysis was conducted on the surveillance data of typhoid/paratyphoid fever in key surveillance areas in China in 2012. The results were compared with those reported to national disease reporting information system. Results The overall incidence of typhoid/paratyphoid fever in 13 surveillance areas was 7.86/lakh. Among 510 laboratory confirmed cases, paratyphoid fever cases accounted for 56.08%, significantly lower than the national average level (63.14%). The surveillance results showed that 147 S. typhi and S. paratyphi strains were isolated. The positive detection rate was 2.55%. The predominated pathogen was S. paratyphi A, accounting for 73.47%. This proportion was much higher than that reported to national disease reporting information system. The positive detection rate and the pathogens detected varied with the surveillance area. The drug-resistance rates of S. typhi and S. paratyphi A to nalidixic acid and ciprofloxacin increased in 2012. PFGE analysis showed there were 14 patterns of S. typhi detected in 2012, in which 3 were new predominant patterns, while JKPX01. CN0001were still the predominant pattern of S. paratyphi A. Conclusion S. paratyphi A is the major pathogen in the surveillance areas. Surveillance for typhoid/paratyphoid fever in key areas can provide more information about the incidence of typhoid/paratyphoid fever in China, but the regular evaluation on the surveillance quality is needed.