Epidemiological characteristics of scarlet fever in Guangdong province, 2005–2017

ObjectiveTo analyze the epidemiologic characteristics of scarlet fever from 2005 to 2017, in Guangdong, and provide evidence for prevention and control of scarlet fever.

MethodsDescriptive epidemiologic analysis was conducted on the spatial, temporal and population distributions of scarlet fever cases reported through national infectious disease reporting and management system in Guangdong from 2005 to 2017. Joinpoint regression software was performed to obtain the average annual percentage changes (AAPC) of incident rates and analyze the incident trends. A total of 66 strains of beta-haemolyticgroup A Streptococcus pyogens (GAS) isolated in 2017 were analyzed through emm typing and antibiotic susceptibility test.

ResultsA total of 20 157 scarlet fever cases were reported in Guangdong from 2005 to 2017, with the annual incidence rates of 1.46/100 000. More cases were reported in summer and winter. High incidences were reported in Pearl River Delta region, with the proportion of 95.79% to the total cases of the province. Most cases were children aged 3 to 7 years. The proportion of children in kindergarten is the highest, followed by scattered children and students. The incidence of scarlet fever in Guangdong was on the rise, and the AAPC was 26.4% (95%CI: 16.9%–36.7%). The most prevalent emm type of pathogenic bacteria was emm12 (65.12%), followed by emm1 (32.56%). The strains were all resistant to erythromycin, clindamycin and tetracycline, and the bacteria were all sensitive to pencillin, cefotaxime and levofloxacin.

ConclusionThe incidence of scarlet fever in Guangdong was on the rise, but no obvious change were observed in the epidemiological patterns. The prevalent emm type of GAS was emm12 and emm1, and strains of GAS were sensitive to pencillin.