Insights into the clinical and molecular epidemiology of an infections outbreak of human parvovirus B19 in France, 2023-2024.

BACKGROUND

The human parvovirus B19 (B19V) infections cycle occurs in 3- to 4-year periods and is responsible for benign childhood erythema infectiosum. It is also associated with transient aplastic crisis in patients with underlying hemolytic diseases and with severe fetal sometimes fatal infection. This study investigated the epidemiological, clinical and molecular characteristics of an unusually large 2023-2024 outbreak of B19V.

METHODS

Laboratory-confirmed cases were retrospectively and prospectively recorded at the Clermont-Ferrand University Hospital, France, between January, 2018 and November, 2023 and between December 2023 and May 2024 (2023/2024), respectively. Demographical and clinical data were investigated for the 2023/2024 period. Subgenome sequences (2690 nt) were obtained by next generation sequencing for virus genotyping and temporal molecular analysis.

RESULTS

The positive rate of B19V positive laboratory-confirmed cases was seven times higher between December 2023 and May 2024 than in the previous 5-year period (14.6 % vs 2.1 %, p < 0.001). No atypical clinical presentation or increased pathogenicity were observed, but this large outbreak resulted in a higher number of severe infections in pregnant women (8/16, 50.0 % of fetal complications) and those with chronic anemia. Phylogenetic analysis revealed that the 2023/2024 outbreak in France and Europe was mainly driven by a pre-existing lineage of B19V 1a subgenotype that emerged in 2017 (95 % highest posterior density interval: 2000-2018).

CONCLUSIONS

The recent epidemic of B19V infections re-illustrates the immunity gap of the post-pandemic COVID-19 pandemic. This highlight the impact of any outbreak on at-risk population and the need for a more global and genomic surveillance.