Nosocomial Malaria Transmissions Resolved by Genomic Analyses-A Retrospective Case Report Study in France: 2007-2021

Between 2007 and 2021 in France, we report 6 nosocomial malaria transmissions (4 during the coronavirus disease 2019 pandemic) confirmed by epidemiological and clinical investigations and parasite whole-genome and phylogenomic analyses based on single-nucleotide polymorphisms and short tandem repeats. Background Exposure of blood to malaria parasites can lead to infection even in the absence of the mosquito vector. During a stay in a healthcare facility, accidental inoculation of the skin with blood from a malaria patient might occur, referred to as nosocomial malaria. Methods Between 2007 and 2021, we identified 6 autochthonous malaria cases that occurred in different French hospitals, originating from nosocomial transmission and imported malaria cases being the infection source. Four cases were observed during the coronavirus disease 2019 pandemic. The genetic relatedness between source and nosocomial infections was evaluated by genome-wide short tandem repeats (STRs) and single-nucleotide polymorphisms (SNPs). Results None of the patients with autochthonous malaria had travel history to an endemic area nor had been transfused. For each case, both the source and recipient patients stayed a few hours in the same ward. After diagnosis, autochthonous cases were treated with antimalarials and all recovered except 1. Genetically, each pair of matched source/nosocomial parasite infections showed <1% of different STRs and <6.9% (<1.5% for monoclonal infections) of different SNPs. Similar levels of genetic differences were obtained for parasite DNA samples that were independently sequenced twice as references of identical infections. Parasite phylogenomics were consistent with travel information reported by the source patients. Conclusions Our study demonstrates that genomics analyses may resolve nosocomial malaria transmissions, despite the uncertainty regarding the modes of contamination. Nosocomial transmission of potentially life-threatening parasites should be taken into consideration in settings or occasions where compliance with universal precautions is not rigorous.

Automated summary

This study investigates nosocomial malaria transmissions in French hospitals using genomic analysis. The results demonstrate the effectiveness of genomic analysis in resolving these transmissions despite uncertainties in the mode of contamination. The study highlights the importance of considering nosocomial transmission of life-threatening parasites when universal precautions are not rigorously followed.