Environmental surface sampling of respiratory and gastrointestinal pathogens during the 2022–2023 Grand Magal of Touba

Background

The Grand Magal of Touba (GMT) pilgrimage is known to be associated with risks of infection, but no studies on the role microbial contamination of the environment has been conducted yet.

Materials and methods

We sampled pilgrims and surfaces in the houses where they were accommodated during the 2022–2023 GMT. Respiratory and gastrointestinal pathogens were tested by qPCR.

Results

Of the 152 surfaces sampled, 10.5 % tested positive for Streptococcus pneumoniae, 5.9 % for Staphylococcus aureus, 16.4 % for SARS-CoV-2 (Severe acute respiratory syndrome Coronavirus 2), 3.9 % for Klebsiella pneumoniae, and 0.6 % for rhinovirus. Only Escherichia coli was positive out of all the gastrointestinal pathogens tested, with enteropathogenic E. coli (EPEC) (23.7 %), and enteroaggregative E. coli (EAEC) (22.4 %) being the most frequent. Of 71 pilgrims tested, 66.2 % acquired a respiratory pathogen, including 16.9 % Haemophilus spp., 7.0 % SARS-CoV-2, 11.3 % Streptococcus pneumoniae, 5.6 % Staphylococcus aureus, 1.4 % rhinovirus, and 2.8 % influenza virus. A further 23.9 % acquired a gastrointestinal pathogen, including EAEC (18.3 %), EPEC (2.8 %), Giardia lamblia (5.6 %) and EIEC/Shigella (2.8 %).

Conclusion

These preliminary results showed a good correlation between results of surface sampling and human infection for SARS-CoV-2 and EAEC. SARS-CoV-2 surface sampling could be used as a surveillance tool during the GMT. Further larger-scale studies are needed to confirm these preliminary findings.