Tick-borne Lyme disease has become much more prevalent in northern Europe and North America in recent years and it is thought that there may be three times more infections in the UK than previous estimates suggest.
There may be as many as 8,000 cases in the UK this year, compared with only a few thousand in recent years and as few as 50 recorded cases twenty years ago. This increase is likely to be due in part to environmental changes that favour the spread of the tick population geographically but also to increased awareness of the problem.
The incidence of cases tends to be more prevalent in spring and summer and in wetter climates. It is particularly prevalent where hiking is a common pastime – this naturally follows grassy and wooded areas.
The disease was first reported in the US in 1977 in Old Lyme, Connecticut, and thus acquired its name. Lyme disease is an infection caused by a type of bacteria that is carried by some species of insects. It is typically spread to humans via infected ticks, which will have already bitten an infected animal such as a deer, mouse, vole or hedgehog. Other insects also carry the disease. In Europe, it’s thought that one to five percent of tick bites will result in Lyme disease. It produces a characteristic ‘bull’s eye’ rash around the bite, but only in about a quarter of cases – it can take months before the rash actually appears. Other early symptoms are similar to a nasty viral infection with headache, fatigue, fever and muscle aches and pains.
If left untreated, Lyme disease symptoms can progress to numbness of the limbs and temporary paralysis of facial muscles. In rare cases, it can lead to inflammation of the heart muscles, which can cause the heart to beat irregularly. Some people suffer chronic pain with debilitating joint and muscle symptoms or mental problems such as extreme fatigue, cognitive dysfunction, anxiety and depression, and even seizures, if not detected and treated.
Diagnosis can be made simply by observing the characteristic rash and treating accordingly, but if the diagnosis is in doubt blood tests are available. Oral antibiotics are very effective if started within the first few weeks after being bitten, but in severe cases you may need antibiotic injections. You cannot become immune to Lyme disease by being bitten once – you can suffer from the disease over and over again with subsequent exposures.
Prevention of Lyme disease is largely dependent on public information programmes and clear notices that increase awareness of the local presence of ticks. In specific outbreaks or designated hiking areas, for example, large scale spraying of affected areas can be carried out. Personal preventative measures are also recommended to prevent tick bites. Once bitten it is important to recognise the symptoms. In the United States, increased awareness of the problem has led to the presence of special tick clinics where antibiotics are dispensed as appropriate.
Prevention measures in tick affected areas:
- Cover bare skin while walking outdoors, tucking trousers into socks and wearing hiking boots
- Wear light coloured clothing so crawling ticks are easier to spot and brush off
- Insect repellent applied to skin and clothes can help to deter ticks
- Use tick prevention on pets as well
- Stick to paths and avoid dense vegetation, particularly wooded or grassy areas in moist and humid environments.
- Shower on return home and check for ticks on the person or crawling ticks on clothing
- Check for signs of tick bites on children and pets
- Wash all clothes at a high temperature.
If you do spot a tick, use fine-tipped tweezers or a specialist tick-removal tool to grab it as close to the skin as possible. Slowly pull upwards, taking care not to squeeze or crush the tick, and put it in a Ziploc bag for testing. Make sure you clean the site of the bite with antiseptic or soap and water afterwards. If you develop flu-like symptoms you need to visit your local primary care practitioner.
Isn’t there a vaccine to protect against Lyme disease?
Well, there was a vaccine but it no longer exists.
LYMErix was developed and introduced in the US in the late 1990s. 1.4 million doses were administered by the end of 2001 and it appeared to be highly effective with up to 90% protection against Lyme disease. However, it was relatively expensive, it did not work in young children and it was only effective against one strain of the bacteria. It was withdrawn in 2002 during a period of anti-vaccination fears that it caused autoimmune reactions in humans and never returned. This was partially based on a 2000 study that found the vaccine contributed to arthritis in hamsters but that was enough to have it withdrawn by the FDA. Now all scientific data is out of date and trials would need to be repeated and public perceptions satisfied before it could be re-introduced. In general, it takes 10-15 years and about 1 billion dollars to develop and license a vaccine and no pharmaceutical company has considered this to be worth the entry cost when they also have to consider the publicity and marketing that would also be needed.
Conversely, canine vaccines are highly effective and widely used and have made scientists and public health authorities think again about further research with centralised government funding to try to halt this growing problem. Last year the US National Institutes of Health (NIH) donated US$23 million to vaccine development and have attempted to persuade drug companies. An Austrian company is currently well into clinical trials of a vaccine that covers against all six strains of Lyme disease and if successful it could be licensed commercially within five years.
Other researchers are proposing to develop a vaccine that can be distributed in areas where Lyme disease is prevalent – it would be in food pellets designed to attract rodents that carry the ticks and then kill off the bacteria inside the ticks that live on the animals – this idea would bypass anti-vaccination fears about the side effects of a human vaccine.
Another body of research that needs further funding has attempted to focus on those people who are suffering from a poorly understood condition that is known as Post Traumatic Lyme Disease Syndrome (PTLDS). It is thought that between 10 and 20% of Lyme patients suffer from the condition with chronic musculoskeletal, neurological and psychological symptoms. A number of private foundations have been set up to try to develop new antibiotics that will wipe out the bacteria from the neurological tissues of the sufferer.