Comparison of the epidemiological patterns of Lyme borreliosis and tick-borne encephalitis in the Czech Republic in 2007-2016.

Background: Lyme borreliosis (LB) and tick-borne encephalitis (TBE) are two vector-borne diseases transmitted by ticks. Both diseases are endemic and have been reported in all regions of the Czech Republic including urban agglomerations, but in varying proportions. Because of the natural conditions in the border areas, the risk of infection is also high for travelers from the neighboring countries such as Austria, Germany, Poland, and Slovakia Materials and Methods: To gain more information on the epidemiology of LB and TBE in the last decade, we analyzed national surveillance data from 2007 to 2016. Results: Incidence of LB in the Czech Republic was 37.3/100,000 population and year (27.6 - 46.1/100,000). Incidence of TBE incidence was 5.7/100,000 (3.4-8.2/100,000) and declined although the trend was not significant (p = 0.155). Difference between the incidences of LB and TBE was increasing in time. Overall male-to-female ratio was 0.84 and 1.51 for LB and TBE, respectively. The age-specific incidences of both infections have a typical two-peak shape, with the first peak in the age group 5-9 years for LB and 15-19 years for TBE. The second peak for both LB and TBE is in the age group 55-64 years. TBE poses a considerable risk to children < 15 years. Among 39,074 cases of LB, the most common clinical manifestations were erythema migrants 62.1% and Lyme neuroborreliosis 25.1%. All 5969 TBE cases manifested itself by affecting nervous system, namely meningo-encephalitis 47.9%, meningoencephalomyelitis 21.8% and meningitis 19.8%. Conclusions: The data evidence the high chance risk of infection with LB and TBE in the Czech Republic. The incidence of both infections shows a bimodal distribution during the year. LB cases are five to six times as frequent as TBE cases. Over the last years, the incidence of LB has remained roughly stable while TBE has shown a downward trend. The present study is unique in allowing the comparison of the incidence rates of LB and TBE over time and space.