Introduction: Lyme disease is caused by an infection with Borrelia burgdorferi sensu latu (B. burgdorferi sl.) which is carried by Ixodes ticks. The disease has not been considered to be endemic in Iceland and no cases of Icelandic origin have been published. The epidemiology of Lyme disease in Iceland has never been studied. The objective of this study was to provide basic epidemiological information about Lyme disease in Iceland.

Material and methods: Included in the study were all pa­­tients who had a measurement of serum antibodies against B. burgdorferi sl. or were diagnosed with Lyme disease (ICD-10, A69.2) at Landspítali University Hospital in Iceland from 2011-2015. Clinical data regarding these patients was retrospectively collected from medical records and the database of the Department of clinical microbiology at Landspítali University Hospital.

Results: 501 patient had a measurement of serum antibodies against B. burgdorferi sl. and 11 patients were clinically diag­nosed with Lyme disease during the study period. 33 patients fulfilled criteria for a confirmed diagnosis of Lyme disease. 32 (97%) patients had erythema migrans and one (3%) patient had neuroborreliosis. An average of 6.6 cases were diagnosed a year (two cases per 100,000 persons/year). All cases originated abroad.

Conclusions: Lyme disease is rare in Iceland. On average around 6 to 7 cases are diagnosed every year, primarily localised infec­tions presenting as erythema migrans. None of the cases had a definitive Icelandic origin and the yearly number of cases has not been increasing.

Table I   Results of testing for antibodies against Borrelia burgdorferi sensu latu in serum samples from patients in Iceland from 2011 to 2015, broken down by year and antibody type.  Number and percentage, n (%).

Table II   Persons who had a measurement of serum antibodies against Borrelia burgdorferi sensu latu in Iceland from 2011 to 2015. Patient demographics, symptoms and epidemiological information. Broken down by results of antibody testing and confirmed cases of Lyme disease. Number and percentage, n (%). Age is given as mean age and standard deviation.