Carriage of Neisseria meningitidis in newly enlisted young military professionals during the COVID-19 pandemic

Abstract

Aim: Invasive meningococcal disease (IMD) is still a major threat not only to the youngest age group of children but also to adolescents and young adults. Higher rates of meningococcal disease have also been reported in specific at-risk groups, such as secondary and tertiary students and members of the military. Infection occurs after close contact with a clinically ill individual, but most often with an asymptomatic carrier. The aim of our study was to determine the prevalence of carriage of N. meningitidis in young persons newly enlisted in the Army of the Czech Republic (ACR). Material and methods: During August 2021, persons entering the service in the ACR were asked to participate in the presented study approved by the Ethics Committee. Nasopharyngeal and oropharyngeal swabs were collected from the study participants in August. A questionnaire survey was administered to each of them after signing an informed consent form. The biological samples were cultured on the day of collection and analysed for N. meningitidis. In case of meningococcal detection, the serogroup of N. meningitidis was determined. For most of the study participants, swabs were repeated after 2-3 months, in October and November. Swabs were also collected from additional participants, namely students entering the first year of bachelor and master studies at a military college. Results: A total of 252 newly recruited young military professionals, 201 males and 51 females, were included in the study. Carriage of N. meningitidis was found in 13 study participants, i.e., 5.2 % of all tested subjects, with a predominance of positive findings in the summer period. All carriers were males while in females, meningococcal carriage was not detected. In carriers, serogroup B was predominant over non-groupable isolates (NG). There was no evidence of carriage of meningococcal groups A, C, W, X, or Y. Meningococcal isolation was significantly more successful from oropharyngeal compared to nasopharyngeal swabs. Only in five of 17 positive findings, meningococci were detected from both the oropharynx and nasopharynx. No isolation was made from the nasopharynx alone. Conclusion: The lower percentage of meningococcal carriage in young military professionals in the Czech Republic in the study period 2021 as compared to similar reports on military collectives from other countries can be attributed to the current epidemic situation, where the measures taken in connection with the efforts to prevent the spread of COVID-19 resulted in the loss of seasonality of respiratory diseases and also their significantly lower incidence. This correlates with a reduction in carriage in the monitored age category.

Keywords: N. meningitidis; carriage; carrier status; invasive meningococcal diseases; meningococcus; military collective.