Tick-Borne Encephalitis and Lyme Disease in Hungary: The Epidemiological Situation Between 1998 and 2008

Diagnosed cases of tick-borne encephalitis (TBE) and Lyme disease (LD) have been reportable infectious diseases in Hungary since 1977 and 1998, respectively. Clinically diagnosed cases have been registered in the National Database of Epidemiological Surveillance System (NDESS). All reported TBE cases are confirmed by laboratory serological and, if necessary, PCR tests, whereas the registered cases of LD are mainly based on the appearance of erythema migrans concurring with possible exposure of tick bite. Our work is the first comparative epidemiological and geographical information analysis of these 2 diseases together. The following demographic data from each individual case (703 TBE and 13,606 LD) recorded in the NDESS were used: Sex, age, the starting date and place of the onset of disease, and a short report from the affected person. The descriptive epidemiological analysis of incidence was carried out using directly standardized rates, and smoothed indirectly standardized incidence ratios were calculated by hierarchical Bayesian methods at the municipality level using a Rapid Inquiry Facility (RIF). The average yearly incidence rate of TBE was 0.64 per 100,000 inhabitants (range, 0.46-0.84) and of LD was 12.37 per 100,000 inhabitants (range, 9.9-18.1), with the highest incidence rates in 1998 for TBE and 2008 for LD. The most affected age groups were men between 15 and 59 years of age for TBE, and women between 45 and 64 years of age for LD. Seasonality, based on the starting date of the illness, was also characterized. Extended areas of high risk were identified in western and northern Hungary, illustrated on high-resolution (municipality level) maps. On the basis of our analysis, it is possible to associate areas and periods of high-risk with characteristics (sex, age, residence) of groups most affected by tick-borne diseases in Hungary.