Seroprevalence of Borrelia burgdorferi sensu lato antibodies in English adult blood donors: A nationwide cross-sectional study, 2021-2022.

BACKGROUND

Estimates of Lyme disease incidence in England are based on reporting of cases with a laboratory-confirmed diagnosis only, underestimating total cases. In 2017 - 2018, two independent reviews commissioned by the UK Government highlighted the lack of official data on Lyme disease prevalence and incidence as a critical knowledge gap.

AIM

To estimate the prevalence of IgG antibodies in the English adult population specific for Borrelia burgdorferi sensu lato (Bbsl), the causative agent of Lyme disease.

METHODS

The prevalence of Bbsl-specific antibodies in the English population was estimated in a cross-sectional cohort, selected from an archive of residual NHS blood donor plasma samples (age range 17 - 84, collected between 2021 - 2022). 10,000 samples were randomly selected proportionate to the population size of each of the nine English administrative regions. 9,994 samples were tested using a standard two-tiered testing strategy, with an IgG/IgM ELISA followed by an IgG immunoblot (array) test for any sera with positive or indeterminate reactivity in the ELISA.

RESULTS

Out of the 9,994 samples tested, 482 were seroreactive by screening ELISA. After two-tier testing, 49 were confirmed positive. Regional and demographic differences in seroprevalence were observed after two-tier testing, but due to the low overall seroprevalence, were not significant upon multivariable analysis.

CONCLUSION

The seroprevalence of Borrelia burgdorferi sensu lato-specific IgG in the English adult population (2021 - 2022), determined using two-tier testing was estimated at 0.49 % (95 % CI 0.36 - 0.65). This is lower than neighbouring UK nation Scotland and other northern European countries.