Human activities predominate in determining changing incidence of tick-borne encephalitis in Europe

Abstract

Explanations for the dynamics of tick-borne disease systems usually focus on changes in the transmission potential in natural enzootic cycles. These are undoubtedly important, but recent analyses reveal that they may not be quantitatively the most significant side of the interaction between infected ticks and humans. Variation in human activities that may impact inadvertently but positively on both the enzootic cycles and the degree of human exposure to those cycles, provide more robust explanations for recent upsurges in tick-borne encephalitis in Europe. This can account for long-term increases in incidence that coincided with post-soviet political independence, for small-scales spatial variation in incidence within a country, and for short-scale fluctuations such as annual spikes in incidence. The patterns of relevant human activities, typically those related to the use of forest resources, are evidently driven and/or constrained by the cultural and socioeconomic circumstances of each population, resulting in contrasting national epidemiological outcomes.

Epidemiological and Ecological Studies of Tick-borne Encephalitis Virus

“…Between 1990 and 2007 an average of 8755 TBE cases per year was reported in Europe and Russia, compared to an average of 2755 cases per year between 1976 and 1989 [133]. In the 1990s there was a dramatic increase in TBE cases in eastern Europe [134][135][136].…”

“…Which factors that contribute the most can differ geographically and is often hard to quantify. At the borders of the current TBEV distribution, climate change may have a role, while changes in TBE cases within core endemic areas appears better explained by socio-economic factors [137][138][139][140][141][142][143][144][145][146][147][148][149][150][151][152]. In the Baltic countries, increased risk of TBE has been correlated to socioeconomic factors, where lower educated, unemployed, and retired individuals are more often unvaccinated and visit the forest more frequently for recreation and picking berries and mushrooms [153].…”

Goat cheese production in Sweden – a pioneering experience in the re-emergence of local food

“…In nature, TBEV is present at endemic foci, maintained in rodent-tick cycles where human infections are ''dead ends'' for further transmission of the virus (Mandl 2005). Several factors, including climate change, socioeconomic changes, and variation in human activities have affected the distribution of both the tick vector and TBEV (Sü ss et al 2008;Randolph 2010), which increases the risks for human infections (Donoso Mantke et al 2008;Elväng et al 2011).…”

Tick-Borne Encephalitis Virus: A General Overview

“…TBE cases have increased steadily since the mid-1970s in Russia, and since the mid-1980s in Switzerland, Sweden, and Finland. In Austria, the only country with extensive systematic vaccination coverage, TBE incidence has decreased progressively since the early 1980s (Randolph, 2002). Russia is the country with the largest geographical range of TBE virus and the highest TBE incidence.…”