Concern about rise in Lyme disease cases

Scotland’s Chief Medical Officer, Sir Harry Burns, has published his annual report covering 2010. In Chapter 6, on zoonoses, Sir Harry says

“One concerning trend in zoonoses, i.e. diseases that can be transmitted from animals to humans, is that shown by the increase in Lyme disease, a tick-borne disorder. The rise cannot be accounted for purely by changes in laboratory protocols or in the number or demographics of patients tested. Variations in climatic conditions and alterations in clinical presentations may have contributed to this continuing rise year on year. This is also likely to be impacted by improved recognition and clinical suspicion.”

In England and Wales, the provisional figures for the first 3 quarters of 2011 have just been released. The laboratory confirmed cases for weeks 1-39 (approx. Jan – Sept) rose from 768 in 2010 to 968 this year – an increase of 26%.

Nobody knows precisely what this rise is due to although better awareness amongst the public and doctors is a likely contributing factor.

It is important to realise that these numbers only cover laboratory confirmed cases; those people diagnosed from the typical rash without a blood test, are not included. If awareness has improved, then the number of people diagnosed at this early stage will also have increased.

Also uncounted are

  • those people who ignored their rash and didn’t bother a doctor;
  • those whose doctor mis-diagnosed the rash as cellulitis or ringworm;
  • those who never saw a rash and whose doctor thinks Lyme disease is unknown outside the New Forest;
  • those whose blood test for Lyme disease came back negative.

All these are without treatment for Lyme disease until they or their doctor put two and two together, eliminate other possibilities and consider Lyme disease seriously, independently of the blood test.

We might have a handle on the number of laboratory confirmed cases each year, but we have no idea of the number of genuine Lyme disease cases in the UK.

How big is the iceberg?