You may have contracted Lyme disease at some point in your life and not even know it, according to a new study in BMJ Global Health. More than 14% of the world’s population — 1 in 7 people— most likely has, or has had, tick-borne Lyme disease, say study authors. Through a pooled data analysis of the available evidence, researchers discovered the presence of antibodies for Borrelia burgdorferi sensu lato (Bb) infection, or Lyme disease, in subjects’ blood.
The medical team searched major research databases and reviewed 137 eligible studies (out of an initial haul of 4196) published through the end of 2021. Statistics were then pooled from 89 studies, involving 158,287 people.
The pooled data analysis revealed that the reported estimated overall global seroprevalence—the presence of antibodies to Bb infection in the blood—was 14.5%.
The three regions with the highest reported seroprevalence were Central Europe (21%), Eastern Asia (16%), and Western Europe (13.5%). At the other end of the scale, the regions with the lowest reported seroprevalence were the Caribbean (2%), Southern Asia (3%), and Oceania (nearly 5.5%).
But the reported pooled Bb seroprevalence in studies — utilizing Western blotting, a widely implemented analytical technique to confirm the presence of specific proteins — was lower than that of studies using other confirmatory methods. In light of this finding, the study authors suggest that the routine use of Western blotting could significantly improve the accuracy of Bb antibody detection.
A smaller pooled analysis of the results of 58 studies in which Western blotting had been used, showed that older age (50+), male sex, residence in a rural area, and being bitten by a tick were all associated with a heightened risk of Bb antibodies.
“Our results indicate that the prevalence of Bb in 2010–2021 was higher than that in 2001–2010,” write the study authors. Possible explanations include ecological changes and factors such as longer summers and warmer winters, lower rainfall, animal migration, fragmentation of arable land, and more time spent outdoors with pets, say study authors.
This systematic review provides a global estimate of the epidemiology of Bb infection in humans. With a high reported pooled seropositivity rate in the total population, Bb infection was most common in Europe. Subgroup analysis showed that the pooled seroprevalence increased steadily in these four subpopulations (the general population, the high-risk population, the tick-bitten population, and the LB-like symptoms population). This report further elaborates on the public health implications of the increasing prevalence of Bb infection. We confirmed that results confirmed by WB are more reliable than those not confirmed by WB when assessing human Bb infection. For risk factors, male sex, age >40 years, residence in rural areas, and suffering from tick bites might increase the risk of Bb infection. However, future studies should be undertaken to verify these conclusions. LB is a widely distributed infectious disease, but it has 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. A more accurate characterization 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 programs.