Identification of JC polyomavirus in upper respiratory samples from Portuguese children.

Background: JC polyomavirus (JCPyV) is ubiquitous in the human population and the causative agent of a rare, fatal and demyelinating disease of the central nervous system named Progressive Multifocal Leukoencephalopathy (PML). The route of JCPyV transmission remains unclear, but high values of seroprevalence suggest an easy and frequent mode, such as respiratory route.

Objectives: The present study aims to investigate the presence of JCPyV in upper respiratory samples and contribute to the elucidation of the JCPyV transmission pathway.

Study Design: Nasopharyngeal swabs from 587 Portuguese individuals, including 380 children (≤18 years) and 207 adults (>18 years), collected for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) diagnosis between September and November 2021 were evaluated for the presence of JCPyV DNA.

Results: JCPyV DNA was detected in 3.1 % of the nasopharyngeal swabs analysed, with higher frequency of detection in samples from children (4.5 %) than from adults (0.5 %) ( = 0.005). Infection with SARS-CoV-2 does not potentiate the presence of JCPyV in upper respiratory tract, once only one adult of 28 years with confirmed SARS-CoV-2 infection showed detectable JCPyV DNA. JCPyV DNA was more frequently detected in respiratory samples from children without SARS-CoV-2 infection (6.4 %). As for this group, children under six years of age presents the highest frequency of detection (10.3 %).

Conclusions: The present study demonstrates that upper respiratory secretions of children, particularly under the age of six, may be implicated in JCPyV transmission, regardless of SARS-CoV-2 infection.