Up until today, all anyone could say in answer to the question “how many people catch Lyme disease each year in the UK?” is “we don’t know!” Doctors would argue “it’s a very small number – only 1200 cases a year”. However, that figure of about 1,200, the only one we have had so far, is just the positive test results. People with the characteristic rash are treated without a test, so they are not counted, and estimates of this number are really just a finger in the air.
Discussions with the National Institute of Health Research about research funding come to a full stop when they say “We need to know how many people are affected by this to know whether we can justify funding any research.”
Now we at last have a new estimate of the annual incidence of Lyme disease. An open access paper published today reports on the results of a study of an amalgamated GP database. This database contains the anonymised GP records of 8.4 million people. Searching for possible Lyme disease diagnoses in this sort of database is not easy and if you heard John Tulloch describe his research at our 2018 conference in Exeter, you would understand.
In summary, this study by Victoria Cairns and colleagues, found that cases of Lyme disease in the UK increased rapidly in the years 2001 to 2012 and based on what they found in this subset of GP records, they estimate there were a total of 7,738 cases in 2012. This informed estimate is 6 times the reported number of cases in 2012, which was 1,249 positive blood tests. Applying this to the reported 1641 cases in England and Wales in 2018 (we don’t have the figure for Scotland that year), would indicate a possible 10,000 cases last year.
So now at least we have some idea of the number of people diagnosed. This is the first step towards funding, not only for research, but also for specialist clinics.
Compared with heart disease and many cancers, 10,000 a year may seem quite small, but even this figure is an underestimate. Bear in mind that this is just an estimate of the number of people diagnosed, not the number of people who actually caught Lyme disease. Given that in 2018 31% of the cases with positive blood tests were late diagnosed, there is some catching up to do. Many GPs don’t think of Lyme disease when someone presents with no memory of a tick bite and with non-specific symptoms that are difficult to pin down and which overlap those of many other diseases and conditions.
How many people are affected by Lyme disease each year? We still don’t know, but at least we can say its almost certainly more than 10,000 people every year, and rising.