OSB archive
OSB archive

Poverty link to tick-borne disease

Cath Harris

Oxford University researchers have linked a surge in the incidence of tick-borne disease in Eastern Europe to poverty levels.

Their study of 14 European countries, published in Parasites and Vectors, associated socio-economic factors in three east European countries with the highest increases in outbreaks of tick-borne encephalitis [TBE]. TBE is a viral infection of the central nervous system caught from the Ixodes ricinus tick.

The scientists attributed the 2009 increases to a reaction to unemployment in countries where pre-existing poverty levels were high. This may have led to a rise in the consumption and commercial use of foods sought in nearby forests, where ticks are found.

‘The bottom line from research is that everyone focuses on the biology of disease,’ Professor Sarah Randolph of the Department of Zoology says. ‘Then we realised it doesn’t rest solely with that but with the other side of the coin - the human exposure to ticks.’

Research in the 1990s by Professor Randolph showed that outbreaks of tick-borne diseases had increased dramatically in many central and eastern European nations. This was ‘likely to have been due to environmental and socio-economic changes associated with the end of communist rule,’ Professor Randolph explains.

Her latest research with colleague Elinor Godfrey has confirmed the link between poverty - as reflected in household expenditure on food - and the prevalence of tick-borne disease. This factor could have an immediate impact on people’s daily activities and behaviour associated with exposure to ticks.

Professor Randolph says: ‘TBE cases were more numerous in 2009 than over the previous five years in almost all countries but the increases were far greater in Latvia, Lithuania and Poland.’ In these nations, outbreaks rose by 91%, 79% and 45% respectively. Outbreaks increased by less than 25% in the other countries studied, which included Sweden, Italy, Estonia and the Czech Republic.

The researchers’ analysis ruled out changes in the weather, such as altered rainfall patterns and variations in temperature with the seasons, as explanations for the surge. Professor Randolph believes the traditional use of forest products in east Europe and commercial opportunities for wild food, particularly in Lithuania and Poland, are significant in explaining her findings.

In addition, the physiological and emotional stress of economic hardship could reduce resistance to disease. Fewer people are getting inoculated because the TBE vaccine is relatively expensive for those on low incomes.

‘Recognition of these risk factors could allow more effective protection through education and a vaccination programme targeted at the economically most vulnerable,’ Professor Randolph says.