The dynamics and interactions of respiratory pathogen carriage among French pilgrims during the 2018 Hajj

Abstract

We conducted this study to describe the dynamics of the acquisition of respiratory pathogens, their potential interactions and risk factors for possible lower respiratory tract infection symptoms (LRTI) among French pilgrims during the 2018 Hajj. Each participant underwent four successive systematic nasopharyngeal swabs before and during their stay in Saudi Arabia. Carriage of the main respiratory pathogens was assessed by PCR. 121 pilgrims were included and 93.4% reported respiratory symptoms during the study period. The acquisition of rhinovirus, coronaviruses and S<i>taphylococcus aureus</i> occurred soon after arrival in Saudi Arabia and rates decreased gradually after days 5 and 6. In contrast, <i>Streptococcus pneumoniae</i> and <i>Klebsiella pneumoniae</i> carriage increased progressively until the end of the stay in Saudi Arabia. <i>Haemophilus influenzae</i> and <i>Moraxella catarrhalis</i> carriage increased starting around days 12 and 13, following an initial clearance. Influenza viruses were rarely isolated. We observed an independent positive mutual association between <i>S. aureus</i> and rhinovirus carriage and between <i>H. influenzae</i> and <i>M. catarrhalis</i> carriage<i>.</i> Dual carriage of <i>H. influenzae</i> and <i>M. catarrhalis</i> was strongly associated with <i>S. pneumoniae</i> carriage (OR = 6.22). Finally, our model showed that <i>M. catarrhalis</i> carriage was negatively associated with <i>K. pneumoniae</i> carriage. Chronic respiratory disease was associated with symptoms of LRTI. <i>K. pneumoniae, M. catarrhalis-S. aureus</i> and <i>H. influenzae</i>-rhinovirus dual carriage was associated with LRTI symptoms. Our data suggest that RTIs at the Hajj are a result of complex interactions between a number of respiratory viruses and bacteria.