The incidence of Lyme disease in the United Kingdom is around three times higher than previously estimated, findings from a retrospective cohort study published in BMJ Open suggest.
“Lyme disease is not as widely known in the U.K. as it is in the United States, but it is far more common in the U.K. than previously thought,” Victoria Cairns, PhD, a consultant statistician from Oxford, England, told Infectious Disease News.
Cairns and colleagues note that Lyme disease has become the most common tick-borne infection in many parts of Europe and in the U.S. According to the CDC, study findings suggest that there are approximately 300,000 cases of Lyme disease diagnosed in the U.S. each year, and WHO estimates that there are 85,000 annual cases in Europe — an estimate that varies widely between and within countries, the researchers wrote.
The official estimate for the U.K. according to the British Infection Association is between 2,000 and 3,000 news cases per year, Cairns and colleagues wrote. They noted that, as in the U.S., “numbers based on centralized reporting are likely to be considerable underestimates” in the U.K. Further, incomplete recording of antibiotic use by specialists and in-hospital may also exacerbate underestimated cases, the researchers wrote.
For their study, they extracted data from the Clinical Practice Research Datalink, a primary care database that covers approximately 8% of the U.K. population across 658 primary care practices. The cohort of 8.4 million patients was registered with general practitioners between January 2001 and December 2012. The researchers identified patients with Lyme disease using an algorithm based on medical codes for Lyme disease, erythema chronicum migrans, laboratory tests and anonymized medical notes to reflect the difficulty in diagnosing the disease. They divided patients into three diagnostic categories — clinically diagnosed Lyme disease, treated suspected Lyme disease and treated possible Lyme disease. They calculated annual incidence rates and the estimated total number of Lyme disease cases separately for each U.K. region.
According to the study, the number of cases increased rapidly between 2001 and 2012. The trend culminated in an estimated incidence rate of 12.1 (95% CI, 11.1-13.2) per 100,000 individuals per year, with a U.K. total of 7,738 Lyme disease cases in 2012. The disease was detected in every region of the U.K., with Scotland reporting the highest incidence rates and most cases, followed by South West and South England. The researchers projected that if the trend continues, the number of cases may surpass 8,000 by the end of the year.
“The general public should become aware of the magnitude of Lyme disease so that they are ready to take preventive measures,” Cairns said. – by Joe Gramigna
Disclosures: Cairns reports no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.