Epidemiological situation of Lyme borreliosis in Belgium, 2003 to 2012

Abstract

Background: Some studies show that the incidence of Lyme borreliosis is increasing in different European countries. In order to evaluate if this is also the case in Belgium, different data sources were consulted to describe the epidemiology of Lyme borreliosis in the country during the last decade.

Methods: Data from two databases were analyzed for the time period 2003-2010 and 2003-2012 for respectively: the registration of minimal clinical data from Belgian hospitals (principal and secondary diagnosis), and a sentinel laboratory network reporting positive laboratory results.

Results: The number of hospitalized cases per year remained stable between 2003 and 2010, ranging from 970 (in 2008) to 1453 (in 2006), with a median of 1132.5 cases per year. Between 2003 and 2012, yearly fluctuations in the number of positive tests were reported by the sentinel laboratory network (with a minimum of 996 positive tests in 2007 and a maximum of 1651 positive tests in 2005), but there is no increasing trend over the study period (median = 1200.5 positive tests per year). The highest incidence rates of hospitalization and the highest reported incidence of positive laboratory results are registered in the provinces of Luxemburg, Limburg, Flemish Brabant and Antwerp, with a typical seasonal pattern (peak in September). The age groups affected most are those from 5 to 14 years and 45 to 69.

Conclusion: Based on hospital records and laboratory results, no increasing trend in Lyme disease was observed over the 2003-2012 period in Belgium. These results are in line with the stable incidence of erythema migrans reported by a sentinel network of general practitionners between 2003 and 2009. Multi-source surveillance of vector-borne diseases should be further implemented.

Keywords: Belgium; Epidemiology; Lyme borreliosis.

Fig. 1

Number of hospitalizations for Lyme borreliosis (principal and secondary diagnosis) by year, 2003–2010, Belgium

Fig. 2

Number of Lyme borreliosis positive tests reported by the sentinel laboratory network, by year, 2003–2012, Belgium

Fig. 3

Number of hospitalizations for Lyme borreliosis, by month, 2003–2010, Belgium. Box plot: The mean and median annual number of cases are presented by month. The length of the box represents the interquartile range (the distance between the 25th and the 75th percentile). The horizontal line in the box represents the median, and the diamond, the mean. The wiskers extend to the group minimum and maximum value

Fig. 4

Number of positive laboratory tests for Lyme borreliosis, by month, 2003–2012, Belgium. Box plot: The mean and median annual number of positive tests are presented by month. The length of the box represents the interquartile range (the distance between the 25th and the 75th percentile). The horizontal line in the box represents the median, and the diamond, the mean. The wiskers extend to the group minimum and maximum value

Fig. 5

Cumulative incidence of hospitalizations for Lyme borreliosis by 100 000 inhabitants, by province, 2003–2010, Belgium

Fig. 6

Reported cumulative incidence of positive laboratory tests for Lyme borreliosis by 100 000 inhabitants, by province, 2003–2012, Belgium