Clinical presentation of Lyme disease in the higher-risk region of Quebec: a retrospective descriptive study.

BACKGROUND: Lyme disease is emerging in Canada. This study aimed to describe the use of serologic testing for the disease in the La Pommeraie health region in southern Quebec between 2012 and 2015 and to describe the clinical presentation of laboratory-confirmed cases.

METHODS: The medical charts of all patients investigated for Lyme disease at the Brome-Missisquoi-Perkins Hospital's laboratory between 2012 and 2015 were reviewed for results of serologic testing. Laboratory diagnosis was based on 2-tiered testing: cases had to have positive results of both the enzyme immunoassay and the Western blot test (IgM or IgG). We collected data on clinical presentation for patients assessed at the hospital or at the La Pommeraie Family Medicine Unit.

RESULTS: Over the study period, 720 patients were investigated for Lyme disease. There was a more than fivefold increase in requests for serologic testing from 2012 (53) to 2015 (273). The number of confirmed cases increased from 2012 (3) to 2013 (19) and remained stable thereafter (19 in 2014, 18 in 2015). Fifty patients were positive for IgM with or without IgG positivity, and 9 patients were IgG-positive only. Chart reviews were completed for 278 of the 720 patients, including 38 of the 59 laboratory-confirmed cases. Among the 29 IgM-positive patients, the most common symptoms were fever (17 patients [59%]), fatigue (14 [48%]), myalgia (12 [41%]) and headaches (10 [34%]). Twenty-three (79%) had some cutaneous manifestation, including specifically erythema migrans (14 [48%]). A tick bite was reported by 11 patients (38%). Of the 44 patients in the entire study population who presented with erythema migrans, 15 (34%) had confirmed Lyme disease.

INTERPRETATION: Requests for serologic testing for Lyme disease increased in the La Pommeraie health region over recent years. Cutaneous manifestations, fever and myalgia were the most common symptoms of IgM-positive cases. Most patients did not report a tick bite.