6th June 2008
Just how harmful can a close encounter with a tick be? Very harmful indeed, reports Nick Warburton.
Thirty-nine-year-old Wendy Fox used to lead an exciting life as a zookeeper. She’d finally found her dream job and was happily married with a teenage son. Then, a few years ago, she had a severe reaction to a tick bite and her life was turned upside down. Paralysed from the waist down, she is now wheelchair-bound and needs a full-time care assistant to look after her while her husband works. Ms Fox was diagnosed with neuroborreliosis or “Chronic Lyme Disease”.
“I am quite severely affected because it caused brain and spinal chord damage and I’ve been left paralysed from the waist down,” she says. “I’ve also got severe vision loss as well because it destroyed my optic nerve and affected the retina of my other eye.”
Ms Fox admits she is a severe case and believes accumulation caused her condition – she’d grown up in a smallholding and was involved in equine sports before becoming a zookeeper. She remembers being bitten regularly by ticks throughout her life.
Guidelines
Her traumatic experience encouraged her to set up Borreliosis and Associated Diseases Awareness UK (BADA-UK) to highlight the threat of tick-borne diseases and prompted her to co-author a set of guidelines on tick management for the CIEH, which should be available for all local authorities later this year. Its main purpose is to inform EHPs about bite prevention, correct tick removal techniques and tick-borne diseases.
With its dense woodland, brushy and grassy areas, the New Forest is a haven for ticks and home to the only tick-borne infection in the UK that is a serious public health concern – Lyme Disease. “Anecdotally, there is a lot of Lyme Disease occurring in the forest,” says Derek Jordan, environmental health manager at New Forest District Council. “It is not a notifiable condition and therefore there is no statistical information about it. It is a particularly nasty condition if it isn’t treated properly.”
Lyme Disease, also called lyme borreliosis, is caused by the bacteria Borrelia burgdorferi, present in the guts of some ticks. While most ticks do not carry the infection, anecdotal evidence suggests that the disease is becoming more frequent, although there is uncertainty about its true extent because the disease’s early rash is often missed or misdiagnosed as another condition.
Rob Smith, who works in the Zoonoses unit at the National Public Health Service in Cardiff, estimates that there are about 800 laboratory-confirmed cases annually, however this figure does not take into account between 1,000-2,000 cases each year that have been diagnosed and treated by GPs.
While not wishing to downplay Lyme Disease as a public health issue, Dr Susan O’Connell, who works for the Health Protection Agency Lyme Borreliosis Unit at Southampton General Hospital, argues that it is important to put the risk in proportion. She is also concerned that inaccurate information from some internet sites is causing confusion and alarm.
“The problem is that there is a lot of misdiagnosis going on of patients with other conditions like Multiple Sclerosis and Motor Neuron disease actually getting misdiagnosed as Lyme,” she says. “It’s important that people are informed about the risks and avoidance measures so they avoid getting infected in the first instance and if they are infected that they are properly diagnosed and treated.”
While the public health threat posed by endemic ticks is relatively low, one emerging trend could increase the risk of human infection from tick-borne diseases in the future.
“When you have farm stewardship and environmental schemes where farmers are paid not to cut down bracken, you’re actually producing the breeding area for the ticks,” says Dr Peter Bates, former head of Parasitology at the Veterinary Laboratory Agency in Surrey. “That, in conjunction with the right to roam, then you are putting people in the areas where ticks are breeding in higher numbers.”
Warm, moist conditions in long grass also help ticks to flourish. “It’s become a bigger issue because of the type of weather we have now,” says Mr Jordan. “I lived in London up until a few years ago and didn’t even know what a tick was. Both my cats had never experienced them but now they don’t go outside where I live unless they’ve been protected to keep ticks off them.”
With the expansion of housing into areas that were once countryside and with a growing interest in ecologically friendly wildlife gardens, EHPs may find they are increasingly called to deal with tick problems. According to Lisa Jameson at the Health Protection Agency, its tick recording scheme has elicited several reports from members of the public in the last year of high levels of tick activity in residential gardens.
Recording ticks
Set up in 2005, the scheme’s aim is to increase the HPA’s understanding of the places where ticks occur, their human and animal biting activity and the impact that external pressures such as climate change and changes in land use may have on their occurrence. The HPA argues that this is essential in order to properly assess the public health risk posed by ticks and tick-borne infections. It is calling on EHPs, and other groups, to help submit tick specimens.
“It would be interesting to see if EHPs have had any reports or been called out for any incidences and whether they’ve seen an increase in the number of people concerned,” says Ms Jameson, who adds that the public should not be overly concerned by the tick problem in residential gardens, as those reported to the HPA have been isolated cases, and that ticks are a much a bigger problem in Europe.
And yet, as Dr Bates writes in the Government Veterinary Journal on the potential for exotic tick-borne diseases of cats and dogs becoming endemic in the UK, the pet travel scheme (PETS), introduced in 2000, could inadvertently transport Europe’s problem to the UK.
Drawing on data from the Dog and Cat Travel and Risk Information (DACTARI) scheme, which measures the incidence of exotic diseases in dogs and cats in Great Britain, 75 per cent of the 52 reported exotic diseases between March 2003 and September 2006, were from cats and dogs entering the UK under PETS.
“It’s not statutory to look for these diseases, so veterinary practices aren’t really informed and have no legal requirement to report any ticks found on dogs,” warns Dr Bates, who predicts that more ticks will enter as more dogs and cats travel.
PETS makes it compulsory to treat animals entering the UK against ticks within 24-48 hours before travel but it is not a fool-proof system and there is talk of the European Union removing this requirement. It may be a slim possibility, but a number of endemic species could become vectors for exotic diseases in the future.
Dr Bates says that the main exotic disease that worries public health experts is tick-borne encephalitis (TBE), which has been spreading across Europe since the break-up of the Soviet Union, transmitted by an infected Ixodes tick. He predicts the Southeast of England faces the greatest long-term threat due to a warmer climate plus ports and airports that could import it.
“Animal Health hasn’t got enough officers at the ports to inspect every cat and dog physically,” he warns. “Basically they come across the border point, the owner shows the animal health officer the certification and the officer hands the transponder to the owner to read off the microchip, so the officer rarely comes into contact with the animal at all.”
Dr O’Connell, however, adds a word of caution. She strongly doubts that TBE will become a problem in the UK. “My understanding from the experts who have looked at this in a lot of detail is that there isn’t a significant risk of it becoming established in this country,” she says.
“I think educational awareness is more important than scaremongering,” adds Dr Bates, who cautions that the impact of climate change on tick populations is hard to predict. “It all depends on what the climate is going to do because it will change the behaviour of the endemic ticks that we have at the moment. These things might not happen but they could happen and authorities should be in some way ready for it and keep an eye on it.”
First line of defence
As most experts will tell you, the first line of defence against ticks is recognising what these blood feeding creatures look like, particularly for those unfamiliar with the tick’s natural habitat – woodland, moorland and grassy areas.
“One of the biggest problems we have in the UK at the moment is the disassociation of 95 per cent of the public from the countryside,” notes Dr Bates. “They are unaware that ticks exist and they are even unaware that there are ticks in their back garden because they are not really in tune with things like that anymore.”
Ticks are tiny, spider-like creatures whose appearance transforms with the different stages of its life cycle. In a nutshell, ticks develop through four stages, starting with the egg and morphing through the larva and nymph until the ticks become adults. Ticks are canny creatures and evolve from one stage to the next after consuming a blood meal from a host, which means they only feed three times in their whole life.
Depending on the different stage of the tick’s life cycle, the creatures feed on a variety of small and large domestic and wild animals as well as humans. Once they start biting, they can take three-to-five days to complete their feast and then drop back into the undergrowth.
Humans usually pick up Lyme Disease from infected nymphs, which are active between February and October with a peak in May/June. Nymphs are quite small and usually cannot be felt on the skin, so a person is unlikely to be aware they are being bitten until a few days later, if at all. Infected adult ticks can also transmit the disease to humans and are much easier to spot because the tick’s body engorges as it feeds.
Most bitten people experience no symptoms, usually because the tick was not infected. In other cases people can remain asymptomatic while carrying the disease. “People have probably got sub-clinical infections they don’t know about if they spend a lot of time outdoors,” says Dr David Hagen, a consultant in communicable disease control at Arun District Council.
For those who do have a reaction, the disease first shows itself as an expanding reddish, round rash in the area around the bite, almost target shaped, although it can be irregular. Early symptoms may resemble influenza with swollen glands near the bite, mild headaches, aching muscles and joints and tiredness. Should these occur, it is advisable to visit a GP for antibiotics. Left untreated the disease may develop over months or years with potentially devastating consequences. “Early diagnosis and treatment is paramount because if the disease is left to disseminate, it can get into the central nervous system and that’s when you can get severe damage,” stresses Ms Fox. “The most common complications are meningitis-type syndromes.”
Because it is impossible to rid ticks from the environment, Dr O’Connell advocates reducing the risk of tick bites and infection through personal protection measures.
Tick leaflet
Mr Jordan concurs. Situated in an area of outstanding natural beauty, New Forest DC maintains a fine balancing act, on the one hand encouraging visitors to enjoy the forest and its wildlife while also advising the public about the threat of tick bites and the need for protection.
The local authority has produced a leaflet that highlights how to avoid getting bitten. The key point to remember is the importance of keeping the skin covered in grassy, brushy or woodland areas. Should a person discover a tick buried in their skin, BADA-UK’s website illustrates how to remove ticks correctly. The Health Protection Agency also provides detailed instructions, recommending the use of either fine pointed tweezers, or tick removal hooks (see panel).
New Forest DC’s advice is clear: “If you think you have been bitten by a tick, go to your doctor and get corrective antibiotic treatment.” The risk may be low but it’s better to be safe than sorry.
http://www.cieh.org/ehp/ehp3.aspx?id=11938
