An attempt to elucidate the increased incidence of tick-borne encephalitis and its spread to higher altitudes in the Czech Republic

Incidence and hospitalisation rates of Lyme borreliosis, France, 2004 to 2012

“…These tick distribution and density changes have been shown to be related to changes in climate (Lindgren et al, 2000;Daniel et al, 2004). The incidences of LB and other tick-borne diseases have also increased in Europe during the same time period.…”

“…In some places this may be an effect of better reporting over time. However, studies from localized areas that have reliable long-term surveillance data show that such incidence increases are real, and that they are related to the same climatic factors that have been shown to be linked to changes in tick abundance (Lindgren, 1998;Lindgren & Gustafson, 2001;Daniel et al, 2004).…”

“…In addition, a large number of other tick species have been reported as carriers of B. burgdorferi s.l., but this does not necessarily mean that these ticks are effective in transmitting the disease. Seasonal climatic conditions limit the latitude and altitude distribution of ticks in Europe (Daniel, 1993;Lindgren et al, 2000;Daniel et al, 2003Daniel et al, , 2004. Both altitude and latitude distribution limits of I. ricinus have changed during recent years in Europe, as described in detail in Section 5.…”

Tick-Borne Encephalitis Virus: A General Overview

“…Sporadically, there were more than 400 cases per year in 1970, 1973, and 1979. A steep increase took place in 1990s (according to data from EPIDAT, National Institute of Public Health in Praguewww.szu.cz), when the annual incidence was more than two-fold higher in comparison with the preceding period, 400-600 cases per year with a maximum of 745 cases in 1995 and 706 in 2000 (Daniel et al, 2004). In the year 2006, the incidence (1,026 cases) of TBE in the Czech Republic was almost twice as high than in the preceding years, the highest ever recorded, indicating significantly increased epidemic activity of this important human pathogen .…”

“…One hypothesis dealing with the increased incidence of the last years is based on impact of climatic changes on the biology of the vector I. ricinus (Gray et al, 2009). Gradual raise of the temperature in the last decades caused prolongation of the period of the tick development within a year and, subsequently, acceleration of its development and increase of the density of its population (Daniel et al, 2004). This allowed the intensification of the circulation of TBE virus, more frequent contact of man with infected ticks, and caused dissemination of the ticks and TBE to regions with no or rare previous records of their incidence (Daniel et al, 2003.…”