Dangerous bugs are on the rise

WHAT IS A TICK?

A tick is an external parasite that sucks the blood of animals and humans. They live in the soil and emerge to climb tall grass, shrubs, bushes and low-level tree branches in search of a blood host. They are vectors of a number of diseases, which they transmit while feeding on the skin. They target specifically the armpit, groin and back of the knee. However, victims do not feel the bite because the tick also injects a toxin that anaesthetises the area. The public is being warned to take extra precautions, particularly while on holiday, following a huge rise in cases of Lyme disease and tick-borne encephalitis (TBE).

WHY YOU SHOULD BE WORRIED

Ticks are second only to mosquitoes for infecting humans with diseases. The two most serious are Lyme disease and TBE.

In its initial stage, Lyme disease may cause a rash and flu-like symptoms. More serious consequences in the months after infection can be facial palsy (paralysis), viral-type meningitis and nerve inflammation, which may lead to pain, disturbance of sensation or clumsiness of movement. Encephalitis (swelling of the brain) is a rare complication. Lyme disease is treated with antibiotics. Some patients still suffer months and even years after treatment from muscle and joint pain, arthritis, cognitive defects, neurological complaints or fatigue.

According to the World Health Organisation (WHO), TBE is a serious acute disease that affects the central nervous system and can lead to long-term neurological complications in 35 to 58 per cent of patients. It can result in serious meningitis, brain inflammation and even death. TBE incubation is six to 14 days and at first can cause increased temperature, headaches, fever, cough and sniffles. A second phase can lead to neck stiffness, severe headaches, photophobia (intolerance to light), delirium and paralysis. One to 2 per cent of these patients die.

No causal treatment for TBE is known at present. The incidence among children increases with age, with boys showing a higher incidence than girls in all age groups. Hospitalisation may often last up to 40 days. In worse-case scenarios, it can last up to four years.

HOW DISEASES ARE SPREADING

Between 1974 and 2003, the number of registered cases in all European countries with a TBE risk rose by an average of 400 per cent. Every year, there are more than 10,000 new cases of TBE infection. Switzerland registered a 58 per cent increase in cases (131 cases in 2004, 207 cases in 2005) and another rise of 27 per cent in 2006 (259 cases). The Czech Republic had a rise of 28 per cent from 2004 to 2005 and from 2005 to 2006 a further rise of 73 per cent (500 cases in 2004, 642 cases in 2005, 1,017 cases in 2006). In Germany, too, the changes are serious (274 cases in 2004, 431 cases in 2005, and 535 cases in 2006), as well as in Poland (174 cases in 2005, 308 cases in 2006). Lyme disease is believed to affect 2,000 people in the UK every year. A decade ago, there were just 10 cases of Lyme disease in Scotland. Last year, that figure had risen to 177. Ticks are common in woodland, heath land and where deer graze.

WHY NUMBERS ARE INCREASING

Global warming, improvements in diagnosis, and various social and economic factors may well be responsible. "The whole problem is building up. On the one hand, the risk areas are spreading; on the other, more and more people are travelling," says Professor Jochen Süss, of the Friedrich-Loeffler-Institute in Jena, Germany.

WATCH YOURSELF WHILE ABROAD

TBE is endemic in regions of 27 European countries: Albania, Austria, Belarus, Bosnia, Croatia, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Italy, Latvia, Liechtenstein, Lithuania, Norway, Poland, Romania, Russia, Serbia, Slovakia, Slovenia, Sweden, Switzerland and Ukraine.

Each year, 60 million people travel to areas where TBE is endemic. Many tourists have no experience in their home countries of TBE or of appropriate preventive measures.

"Given the continual growth in the numbers of UK tourists in endemic countries, it is only a question of time before this group too finds an increase in the number of TBE cases," says Professor Michael Kunze of the Institute of Social Medicine, Centre of Public Health, Medical University of Vienna.

"Travellers from the UK need to be made aware that, once the disease has broken out, there is no effective treatment for sequelae - conditions that can develop in consequence. Immunisation with a TBE vaccine, in the context of preventive travel medicine, is the only method that offers lasting protection over the longer period."

Travellers returning from an endemic area who complain of high temperature, paralysis and other symptoms associated with the central nervous system should consult a doctor immediately, especially if they have not yet been vaccinated against TBE.

WHERE YOU CAN CATCH LYME DISEASE IN THE UK

Exmoor, the New Forest, the South Downs, Wiltshire, Berkshire, Thetford Forest, the Lake District, the Yorkshire Moors and the Scottish Highlands.

TYPES OF TICKS

Around 850 species of tick have been described in the world as a whole. In Europe, eight of the group known as hard ticks have become particularly important as vectors that pass on TBE and Lyme disease. The most important and most widespread of these is Ixodes ricinus, the sheep tick. The body of the female is capable of massive stretching: it can absorb approximately 100 to 200 times its body mass in blood, which increases its volume by a factor of 120.

HOW TICKS FIND YOU

Contrary to the widely held assumption, ticks do not climb trees to drop down on to their victims. Instead, they tend to move about on the ground, in tall grass or in scrub and undergrowth, where they are brushed off on to their unsuspecting hosts: mice, hedgehogs, deer, birds or humans.

A contact time of a few fractions of a second is all it takes for the tick to attach itself to the host's skin (animal or human). The tick uses a sensory structure, called Haller's organ, on the last segment of its first pair of legs to orient itself to suck the blood. It can use this and other sensory organs to react to thermal, chemical and physical stimuli such as vibrations and variations in temperature caused by a passing animal or human. Ticks prefer warm, moist, dark areas of the body.

PERFECT WEATHER CONDITIONS

Humidity and warmth are ideal conditions for ticks. They are particularly active after a rainy day in summer. As long as the ground in the woodland is still damp, ticks can even survive quite long dry periods. They are less active in the cold.

"Mild winters like the one we've just had ensure that a large number of ticks will survive," says Professor Süss. "Recently in Europe, the season for ticks has been significantly longer."

In general, a slow spread of risk areas has been observed, probably due to global warming. In Finland, for example, the virus can now be found just 200km south of the Arctic Circle.

PREVENTION

Use an insect repellent that is effective against ticks; avoid wearing shorts in rural and wooded areas; be sure to tuck trousers into socks; or cover all exposed skin with protective clothing.

Inspect your skin for ticks and remove as soon as possible with fine-tipped tweezers (though TBE transmission can happen instantly). Avoid unpasteurised milk, which may also be infected with the TBE virus in endemic regions.

"Vaccination is recommended to everyone living in or travelling to areas where it is endemic - children as well as adults," says Professor Kunze. "Another important factor leading to disease cases arises when booster doses of the vaccine are not given in time."

The best time for the TBE vaccine to be given is in winter, to ensure that vaccine protection has been achieved before the tick season starts in the spring.

Vaccination in Austria against TBE resulted in a drastic reduction in the number of cases from 677 in 1979 to 54 cases in 2001 with a vaccination rate of 87 per cent, the best figure for the whole of Europe. The record lowest number of cases was 41, achieved in 1999.

For more information, visit www.masta-travel-health.com/tickalert and www.tick-victims.info, the first pan-European TBE network for victims, offering support and a wide range of services and information

How to remove a tick

* You need to remove the whole tick without leaving the mouth part embedded in the skin.

* Grasp the tick firmly and as close to the skin as possible.

In a steady motion, pull the tick's body away directly outwards without jerking or twisting.

* Specialist tick-removal tools can be bought at veterinary clinics and pet shops.

* Pointed tweezers can be used to remove the tick, but you need to take care not to squeeze the tick and release infectious agents and allergens back into your body.

* Don't try to use a flame or cigarette on the tick. And don't squeeze the tick.

Interesting? Click here to explore further