A recent analysis estimates more than one-tenth of the world’s population likely has or at some point had tick-borne Lyme disease.
Research published in the peer-reviewed journal BMJ Global Health found that more than 14 per cent of the global populace had antibodies to Lyme disease in their blood.
Certain regions in Europe and Asia reported the highest rates of Lyme disease, with men 50 and older living in rural areas most at risk, the researchers say.
The researchers add, however, that more studies are needed to improve the accuracy of the global estimates.
“LB (Lyme borreliosis) is a widely distributed infectious disease, but it has not received much attention worldwide,” the study concludes.
The authors say a major public health challenge is predicting when and where there will be a risk of infection, but that more accurately characterizing global distribution will help guide epidemiology and identify risk factors for the disease.
Lyme disease occurs through tick bites and varies between people, sometimes presenting itself later without any prior signs or symptoms.
A commonly reported sign of Lyme disease is an expanding skin rash that looks like a target or “bull’s eye.”
Other early signs and symptoms include fever, chills, fatigue, headache, swollen lymph nodes and muscle and joint aches.
If left untreated, an infection can spread to the joints, heart and nervous system, although early diagnosis and treatment can help prevent further complications.
The researchers involved in the study say Lyme disease has continued to spread around the world, but disagreement exists on how common it is globally.
As part of their analysis, the researchers searched databases and pulled 4,196 studies, published between January 1984 and December 2021, ultimately reviewing 137.
They then gathered data from 89 studies, involving 158,287 people.
The data showed an estimated global seroprevalence, or the presence of antibodies in the blood, to Lyme disease infection of 14.5 per cent.
Central Europe reported the highest rate at approximately 21 per cent, followed by eastern Asia at nearly 16 per cent, western Europe at 13.5 per cent and eastern Europe at 10.4 per cent.
Regions with the lowest rates included the Caribbean (two per cent), southern Asia (three per cent) and Oceania (4.1 per cent).
North and South America each had rates of 9.4 and 8.7 per cent, respectively.
The study’s authors say that using an analytical technique called Western blotting could significantly improve the accuracy of antibody detection.
A smaller analysis of 58 studies using this method showed men 50 and older who lived in rural areas and were bitten by a tick were associated with a heightened risk of having antibodies.
The researchers also found infection rates in 2010-21 were higher compared to 2001-10 on average.
They say this may be due to factors such as longer summers, warmer winters, lower rainfall, animal migration, fragmentation of arable land and forest cover due to human activity, as well as humans possibly spending more time outdoors with pets.
The researchers point to the lack of long-term studies in their analysis as being a limit to their findings.
Most of the reports did not define high-risk groups in their studies and the researchers say they were unable to determine whether antibody positivity affects the risk of developing Lyme disease or recurrence in the long term.