More than 14% of people globally have been exposed to the tick-transmitted pathogen that causes Lyme disease, researchers estimate.

In a systematic review and meta-analysis, which included 89 studies of 158, 287 people, an estimated 14.5% of people globally had antibodies in their blood to a Borrelia burgdorferi sensu lato (Bb) infection.

The top three regions for Bb seroprevalence – where people test positive for a disease based on blood specimens - were Central Europe (21), Eastern Asia (16%) and Western Europe (14%), according to the analysis published in BMJ Global Health.

In contrast, the reported prevalence was lowest in the Caribbean (2%), Southern Asia (3%) and Oceania (5%).

Potential risk factors associated with Bb infection were being male, being aged 50 years and over and older, living in a rural area and suffering from tick bites.

The most common clinical manifestation of Lyme disease, also known as Lyme borreliosis (LB), was an enlarged erythema on the skin, usually at the site of the tick bite.

However, the infecting agent can spread to other tissues and organs, potentially affecting the nervous system, joints, heart and skin, the authors noted.

Their results indicated that the prevalence of Bb infection in 2010-2021 was higher than that in 2001-2010, the researchers said, noting that tick populations have expanded globally and geographically in recent years.

‘This may be related to ecological changes and anthropogenic factors, such as longer summers and warmer winters, changes in precipitation during dry months, animal migration, fragmentation of arable land and forest cover due to human activities and the prevalence of outdoor activities,’ they wrote.

Yet despite LB being a widely distributed infectious disease, it had not received much attention worldwide.

‘One of the major public health challenges regarding LB is the ability to predict when and where there is a risk of Bb infection,’ the study authors said.

‘A more accurate characterisation of the global distribution of Bb infection would guide the circulating epidemiology of LB and identify risk factors for the disease, which could inform the development of public health response policies and LB control programmes.’

The analysis also found that the seropositivity rate from studies where a technique called Western blotting (WB) had been used to confirm results was more reliable than the seropositivity rate in studies with non-WB-confirmed results.

‘These results suggest that WB confirmation could reduce false positivity to some degree and improve specifity,’ the authors said.