Analysis of group A streptococcus detection and transmission factors in school scarlet fever cluster epidemic in Tianjin City

Objective To investigate the infection of group A streptococcus (GAS) in the same class of scarlet fever cases in schools reporting the clustering epidemic, and to analyze the related factors affecting the detection and transmission of GAS.Methods The classes with scarlet fever cases in schools reporting the clustering epidemic of scarlet fever in Tianjin from 2017 to 2019 were selected. Pharyngeal swab samples were collected from other students in the class except for the patients to carry out GAS isolation and identification. Conditional Logistic regression was used to analyze the influencing factors of GAS detection.Results The total positive rate of GAS in 15 classes was 21.02%. There was a positive correlation between the positive rate of GAS and the number of cases of scarlet fever in the class (rspearman=0.820, P=0.000). Pharyngeal pain (OR=2.534, 95%CI:1.608-3.992) and tonsillar enlargement (OR=1.902, 95%CI:1.153-3.138) were the risk factors for the detection of GAS. There was no significant difference between the distance between the seat and the latest scarlet fever case (P>0.05).Conclusion We should pay attention to the personnel with sore throat and swollen tonsils in the school epidemic of scarlet fever, adopt the same management method as the case, and judge the close contacts in the case class, which should not be limited to the students around the case.