Lyme disease risk higher than thought

The risk of Lyme disease in the UK is greater than previously thought, scientists say.

A study by researchers at Bristol University found a much higher proportion of ticks infected with the disease-causing bacterium than had previously been reported.

Lyme disease is a debilitating chronic infection caused by the bacterium Borrelia burgdorferi. People - and some animals, including dogs - can become infected after being bitten by an infected tick.

Signs of the disease include a characteristic circular red rash, which may look like a bulls eye on a dart board, followed by flu-like symptoms such as tiredness, headaches and muscle or joint pain.

If untreated, the disease can affect the joints and nervous system, causing a range of related health problems.

In the study, researchers asked vets across England, Scotland and Wales to select dogs at random and check them for the presence of ticks.

As pet dogs generally share the same environment and visit the same outdoor areas as their owners, the dogs exposure to infected ticks could provide an index of the likely risk to humans.

Of 3,534 dogs inspected at the vet clinics between March and October 2009, some 14.9 per cent were found to have ticks. Of the ones that could be tested, 2.3 per cent were positive for the Borrelia bacteria.

However, the expected prevalence of infected ticks in dogs is 0.5 per cent, or 881 infected ticks per 100,000 dogs.

The researchers said this suggested the prevalence of Borrelia in the UK tick population is considerably higher than previously thought.

Cases of Lyme disease in the UK have been rising in recent years. In 2010 there were 953 reported cases in England and Wales, but the level of under-reporting is likely to be considerable, the researchers said.

Faith Smith, who led the study, said: "Lyme disease appears to be a rapidly growing problem in the UK with important health and economic impacts in terms of loss of working hours and potential decrease in tourism to tick hotspots.

"Without considerably better surveillance and routine diagnostic testing, Lyme disease is only likely to become more prevalent.

"In particular, future warmer winters might well extend the period over which ticks are active seasonally, while growing wild reservoir host populations, such as deer, will allow the tick population to expand."

The study is published in the journal Comparative Immunology, Microbiology and Infectious Diseases.

This article was published on Wed 25 January 2012