Socio‐economic factors in the differential upsurge of tick‐borne encephalitis in central and Eastern Europe

Abstract

Tick-borne encephalitis (TBE), the most serious widespread vector-borne disease of humans in Europe, increased from 2- to 30-fold in many Central and Eastern European countries from 1992 to 1993, coinciding with independence from Soviet rule. Unemployment and low income have been shown in Latvia to be statistically associated with high-risk behaviour involving harvest of wild foods from tick-infested forests, and also with not being vaccinated against TBE. Archival data for 1970--2005 record major changes in the agricultural and industrial sectors, and consequent changes in the abiotic and biotic environment and socio-economic conditions, which could have increased the abundance of infected ticks and the contact of humans with those ticks. For example, abandoned agricultural fields became suitable for rodent transmission hosts; use of pesticides and emissions of atmospheric industrial pollutants plummeted; wildlife hosts for ticks increased; tick populations appear to have responded; unemployment and inequality increased in all countries. These factors, by acting synergistically but differentially between and within each country, can explain the marked spatio-temporal heterogeneities in TBE epidemiology better than can climate change alone, which is too uniform across wide areas. Different degrees of socio-economic upheaval caused by political transition in Estonia, Latvia, Lithuania, Slovenia and the Czech Republic can apparently explain the marked variation in TBE upsurge. Causal linkage between national socio-economic conditions and epidemiology is strongly indicated by striking correlations across eight countries between the degree of upsurge of TBE and both poverty and household expenditure on food (R2 = 0.533 and 0.716, respectively).

Rodents as Sentinels for the Prevalence of Tick-Borne Encephalitis Virus

“…In addition, TBEV infections emerged in new areas, for example, southern Sweden, Denmark, and France, possibly because of socioeconomic or climate changes (Haglund 2002, Brö ker and Gniel 2003, Donoso Mantke et al 2008, Sumilo et al 2008, Fomsgaard et al 2009). …”

From childhood to golden age: increased mobility – increased risk of contracting tick-borne encephalitis?

“…Unemployment rose in many countries, leading not only to high-risk behaviour involving harvesting mushrooms and other wild foods in infested forests but also to lower vaccination rates. All of these factors taken together are able to explain the spatio-temporal heterogeneities in TBE epidemiology better than climate change alone, which is too uniform across wide areas [16]. Overall, therefore, human behaviour, driven by a wide variety of factors, is crucially important in the emergence of zoonotic diseases [17].…”

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].…”