Incidence of Lyme disease may be ‘three times higher’ than estimate - study

Irish expert ‘not surprised’ at UK data suggesting much higher number of tick-borne infections

Lyme disease is a bacterial infection passed on through the bite of an infected tick.

Lyme disease is a bacterial infection passed on through the bite of an infected tick.

 

Health authorities may be greatly underestimating the number of Lyme disease cases in Ireland, according to a medical expert, after UK research suggested the rate of infection there was three times higher than previously recorded.

Lyme disease is a bacterial infection passed on through the bite of an infected tick. Early signs may include a rash around the area of the bite, flu-like symptoms and neurological symptoms.

Permanent joint or nerve damage can arise from the disease if it is not promptly treated with antibiotics.

The study, published by the British Medical Journal on Tuesday, drew on anonymised medical information submitted by family doctors to a UK database between 2001 and 2012.

The researchers categorised diagnoses of Lyme disease as those that had been diagnosed clinically (42 per cent), or suspected and treated (47 per cent), or considered possible and treated (11 per cent).

Using this method, the estimated annual incidence rate in 2012 was 12.1 cases per 100,000 of the population, dramatically higher than the 1.84 per 100,000 rate which was previously recorded for England and Wales.

This new figure estimates there were 7,738 cases in the UK in 2012, compared with previous estimates of 2,000-3,000 cases per year.

The figure for 2012 is around three times higher than previous estimates have suggested, and if these trends continue, the number of new UK cases could top 8,000 in 2019, the researchers said.

Jack Lambert, a consultant specialist in infectious disease at Dublin’s Mater Hospital, said he was not surprised by the figures and he believed Ireland would have similar results.

“A tick is the size of a sesame seed, so a lot of people do not know when they have a tick. Then half of the people don’t get the classic rash. I’d suggest the number of cases diagnosed in Ireland is just the tip of the iceberg,” Dr Lambert said.

“My guesstimate for Ireland is that there are around 2,500 cases per year.”

The official estimate is that Ireland has between 200 and 300 cases of Lyme disease annually.

“I’m taking care of 20 people from Donegal who have the disease. How could there be only 200 or 300 cases each year if there are 20 people in Donegal alone who have it?” Dr Lambert added. “I think we’re missing around 80 per cent of the cases. There is a lot more Lyme than Irish or UK governments are acknowledging.”

However, Prof Sally Cutler, professor of medical microbiology at the University of East London, believes the figures in the study are likely to be an “overestimation”.

“I would advise caution when interpreting the number of Lyme disease cases provided in this study as they are likely to be an overestimation,” Prof Cutler said. “Continued observation is a priority, though personally I favour use of more rigorous data than that used in this study.”

She added: “Despite its limitations and potential for underestimation, this study was reassuring in that suspect cases were receiving benefit of doubt from their GPs and were being treated.”