Scrutinising Lyme disease in the UK

Abstract

As discussed in your Editorial,1The Lancet Infectious DiseasesScrutinising Lyme disease in the UK.Lancet Infect Dis. 2019; 19: 915Summary Full Text Full Text PDF PubMed Scopus (1) Google Scholar Eugene Shapiro's primary objection to our Lyme disease study appears to be in connection with the finding that only 22% of the cases had a record of the rash, erythema migrans, whereas he says up to 90% of Lyme disease cases have the rash.2Shapiro E Lyme disease incidence three times higher in UK than previously thought, study suggests.Helio. 2019; https://www.healio.com/infectious-disease/emerging-diseases/news/online/%7B18f59b0c-3d16-4e7b-b68e-7a37653bf855%7D/lyme-disease-incidence-three-times-higher-in-uk-than-previously-thought-study-suggestsDate accessed: February 14, 2020Google Scholar, 3Cairns V Wallenhorst C Rietbrock S Martinez C Incidence of Lyme disease in the UK: a population-based cohort study.BMJ Open. 2019; 9e025916Crossref PubMed Scopus (25) Google Scholar If most cases had the rash, then laboratory testing would often not be necessary because patients presenting with the rash can be diagnosed and treated without the need for blood tests. Shapiro has defended his claim that most Lyme disease cases have the rash with two studies, both of which identified patients with erythema migrans or a later manifestation of Lyme disease, whereas patients not presenting with those symptoms were excluded.4Shapiro ED Wormser GP Controversies about Lyme disease—reply.JAMA. 2018; 320: 2482-2483Crossref PubMed Scopus (3) Google Scholar As a result, the prevalence of erythema migrans is overestimated and misleading. Other studies with overestimated proportions of cases with the rash have included self-selected patients who presented to hospital because they had the rash. An impression of the true proportion of cases with the rash is best obtained from studies that aimed to collect all cases diagnosed by general practitioners (GPs). One example of a reasonably complete dataset of Lyme disease patients is by Sears and colleagues5Sears SD Smith P Mills DA et al.Report to Maine legislature: Lyme disease.https://www.maine.gov/dhhs/mecdc/infectious-disease/epi/vector-borne/lyme/documents/lyme-legislature-2010.pdfDate: 2010Date accessed: January 22, 2020Google Scholar who found that 43% of patients with confirmed or probable Lyme disease had the rash. Some of the suspected cases might have had Lyme disease and been treated, but they were not included in the calculation. The UK study by Lovett and colleagues6Lovett JK Evans PH O'Connell S et al.Neuroborreliosis in the South West of England.Epidemiol Infect. 2008; 136: 1707-1711Crossref PubMed Scopus (22) Google Scholar found that many of the Lyme disease cases who presented to hospital had erythema migrans, and they were included because they met the study criteria of having a clinical manifestation. The more complicated cases might have been referred to hospital. Of those with neuroborreliosis, 36% had a GP record of a rash thought to be erythema migrans. Only 25% of the cases had the rash in the original study by Steere and colleagues7Steere AC Malawista SE Snydman DR et al.Lyme arthritis: an epidemic of oligoarticular arthritis in children and adults in three Connecticut communities.Arthritis Rheum. 1977; 20: 7-17Crossref PubMed Scopus (916) Google Scholar identifying Lyme disease—a study in which having the rash was not one of the criteria for being included. The 22% of cases with the rash in our study is somewhat lower than the proportions seen in other GP studies, which suggests that some of the suspected and treated cases in our study might not have had Lyme disease. However, that might have been counterbalanced, to some extent, by our conservative selection procedure leading to the exclusion of some cases. Diagnosis of Lyme disease can be difficult, and it is sometimes uncertain so any survey of GP data will contain some disputed results. I declare no competing interests. Scrutinising Lyme disease in the UKConcerns over Lyme disease in the UK have been gaining attention. Most recently a study in BMJ Open by Victoria Cairns and colleagues received broad coverage in the press. This study reported that the incidence of the disease was three times higher than that of previous estimates and that people throughout the UK are at risk. This is clearly an attention grabbing finding. However, this conclusion might not be as clear-cut as it seems and, given the passionate advocacy associated with this disease, it is essential that care is taken over findings that could influence perceptions of its scale. Full-Text PDF