Surveillance for respiratory infectious diseases caused by 6 common viruses in a recruit training site in the Northern region of China

BACKGROUND Recruit training sites are places with a high incidence of respiratory infectious diseases. Effective surveillance for acute respiratory infectious diseases in a recruit training site is an important way to prevent disease outbreaks. METHODS Eight hundred recruits (722 males and 78 females) enlisted in autumn 2015 received a background survey within 24 h of settlement at the recruit training site, including their general personal information, vaccination history, mental status and clinical symptoms. Then, nasopharyngeal swabs of these recruits were collected to detect common respiratory pathogens [influenza virus type A, influenza virus type B, adenovirus (Adv), human respiratory syncytial virus, human bocavirus and human metapneumovirus] by PCR. In addition, fasting venous blood was collected in the morning for adenovirus IgG antibody detection. During the three months of training, the recruits were monitored for symptoms of respiratory infection, and nasopharyngeal swabs were collected from those with an axillary temperature ≥38 °C and other respiratory symptoms within 4 h of symptom onset. Samples were further examined by PCR. RESULTS Among the 795 effective nasopharyngeal swab samples collected during survey, two cases of group C type 1 adenovirus were identified by PCR. During the 3 months of training, fever and respiratory symptoms occurred in 39 recruits (incidence rate of 4.9%) and 5 cases of adenovirus were detected (positive rate of 12.8%). Genotyping showed 3 cases of type 4 adenovirus and 2 of type 3 adenovirus. No type 7, 14 or 55 adenovirus was detected. The Adv-IgG positive rate of recruits was 48.2%. Among the 5 Adv positive cases with fever and respiratory symptoms, 4 were Adv-IgG positive. CONCLUSION The pathogen carrier rate in recruits was low, and only group C adenovirus, which causes mild infection in humans, was detected. No respiratory outbreak was observed at the recruit training site, and sporadic cases were mainly caused by type 3 and type 4 adenoviruses.