Ticks and Lyme Disease


This article was originally published in The Bushcraft Journal issue 8 in April 2016.  Thanks to its author Jules Bristow for allowing us to reprint it here.  Jules studied chemical ecology and is a keen amateur naturalist and bushcrafter who we are delighted to have as part of the Jack Raven Bushcraft team.

What lurks in the undergrowth

In this time of increasing disconnection from the natural world I seem to spend a lot of time reassuring people that our wild places are not nearly as frightening as they think, but it is important to keep in mind that they still pose some threats that should be respected.  Compared to the great human suffering caused by mosquito-born diseases in the tropics, we in the UK are comparatively lucky in vector-borne disease stakes, able to enjoy the great outdoors without too much concern about being bitten by something that can transmit something unpleasant.

One vector-borne disease that we do have to contend with though is Lyme Disease and its close bacterial relatives, which are transmitted by the bites of ticks.  Lyme Disease can be life changing and debilitating as is thoroughly illustrated by Sophie Tynan’s article which follows this one, and it is still often initially not correctly diagnosed which can lead to severe and possibly incurable complications.  With the number of confirmed cases in the UK rising from 346 in 2003 to almost 1000 in 2015, it is extremely important to remain vigilant for the ticks that transmit it and seek prompt diagnosis if you suspect you may be infected.

ticks

Image – By Maksim https://commons.wikimedia.org/w/index.php?curid=628930

Lyme Disease is transmitted to humans by ticks, small invertebrates that suck blood in order to obtain protein for their eggs to develop. In the UK it is known to be carried by three different species of ticks:

  • Ixodes ricinus, the sheep tick which feeds primarily on sheep and deer
  • The hedgehog tick Ixodes hexagonus
  • The fox or English dog tick Ixodes canisuga which feed mostly on other small mammals.
ticks

Sheep tick Ixodes ricinus, unfed on human skin Image – James Lindsey https://commons.wikimedia.org/wiki/File:Ixodes.ricinus.searching.jpg

 

ticks

Sheep tick Ixodes ricinus, swollen with blood after feeding. Image – Thomas Zimmermann https://commons.wikimedia.org/wiki/Ixodes_ricinus#/media/File:Ixodes_ricinus_08.jpg

 

ticks

Hedgehog tick Ixodes hexagonus Image – André Karwath https://commons.wikimedia.org/wiki/Ixodes_hexagonus#/media/File:Ixodes_hexagonus_%28aka%29.jpg

 

They are not especially discriminating however and if a human walks past the patch of undergrowth where they’re waiting to hitch a lift on a new host they’d be happy to make you a warm meal.

Ticks are active from late spring to autumn, becoming dormant only in the coldest months.  The NHS Lyme disease website lists the following areas of the UK as being a particularly high risk for ticks:

  • Exmoor
  • The New Forest and other rural areas of Hampshire
  • The South Downs
  • Wiltshire and Berkshire
  • Surrey and West Sussex
  • Thetford Forest in Norfolk
  • The Lake District
  • The North York Moors
  • The Scottish Highlands

So what can you do to avoid infections?  Well, encouragingly a randomised controlled trial showed that infections were less common in people who received education about ticks, so simply by reading this article you are improving your chances! The first step in preventing Lyme disease is to do everything you can to avoid being bitten.  A good start is to stay out of long grass and bracken in areas where Lyme disease is known to be active, as these are the sorts of areas that ticks wait for their prey.  Paul Kirtley does an excellent job of busting the various myths about bracken making a good bed in this video https://www.youtube.com/watch?v=lMrbOz-LsU4 but one of the many reasons is that while collecting and sleeping on bracken you are very likely to be exposed to ticks.  You can also try to reduce the area of your skin that’s available for ticks to find, by wearing long trousers and tucking them into your socks.  A recent study of best practice for tick bite prevention and tick removal http://www.bmj.com/content/347/bmj.f7123 found that clothes impregnated with the insecticide permethrin were effective in reducing the incidence of tick bites, although they do need retreating frequently to remain effective.

The next line of defence is to use a repellant, a substance that you can rub on your skin that ticks find unpleasant smelling or that masks the smells that may tell them you would make a tasty meal. Trans-p-methane-3,8-diol (PMD), or lemon eucalyptus oil to its friends, has been shown to be highly repellent toward ticks and in laboratory studies was still providing some protection 48 hours later.  By contrast there is little evidence for the effectiveness of DEET against ticks, and what evidence there is seems to suggest it only has a short-term effect. (It should be noted that this is different from the situation for mosquitoes, against which DEET offers better protection).  Also note that lemon eucalyptus oil is the oil of a particular tree called Corymbia citriodora, and NOT a mixture of regular eucalyptus oil and lemon oil.

If a tick does bite you, the faster you can remove it, the less chance it will have to get bacteria into your bloodstream.  If you’re in a high risk area you should check yourself every few hours for ticks, particularly at warm joints which ticks love such as your armpits or where your thighs meet your crotch. This is easiest with the aid of a mirror, and easier (and possibly more enjoyable!) with the aid of a partner.

Tick removal is a step which seems to have produced the most dangerous home remedies.  Trying to suffocate the ticks with petroleum jelly, nail polish or rubbing alcohol is likely to be ineffective as ticks respire very slowly so can keep feeding without air long enough to infect you, and if you do manage to damage or kill a tick by one of these methods or using a lighted match there’s a danger that it will vomit infectious material into the wound because of stress or that parts of it will be left in your skin, posing an infection risk.  (Needless to say combining rubbing alcohol and a lighted match would be a terrible idea.)

At present the evidence suggests that the safest method of tick removal in humans is to use fine-tipped tweezers – evidence for the effectiveness of a specialist Tick Twister tick removal tool only comes from veterinary medicine.  However, if you’re not comfortable with tweezers the removal tool is probably a better bet than any of the other methods out there.  If using sharp nosed tweezers, grip the tick as close to the point where it has inserted its mouthparts into the skin as you can and lift it away.

ticks

Image – Centre for Disease Control https://commons.wikimedia.org/wiki/Category:Tick_removal#/media/File:Tickremoval.png

 

Image – OTOM

 

Although the characteristic bull’s eye rash is probably the best known Lyme disease symptom, it only appears in around 60% of patients and unfortunately it is harder to detect on darker skin tones – a study carried out in Maryland, USA, found that the rash was six times more likely to be reported by white people than by African Americans http://aje.oxfordjournals.org/content/152/8/756.full.pdf.  I would therefore recommend that bushcrafters of colour take extra care to get flu-like symptoms checked out after spending time outdoors, as this indicator is easy to miss.

ticks and lymes disease

Image – Hannah Garrison https://commons.wikimedia.org/wiki/File:Lymne-ziekte-na-ongeveer-3-weken.jpg

Other symptoms include:

  • unexplained headaches and neck stiffness,
  • flu-like symptoms,
  • facial palsy (tremors or immobility),
  • arthralgia (joint pain),
  • heart palpitations,
  • dizziness

If you experience any of these within a few weeks of being bitten by a tick, or of being somewhere you know ticks are present even if you didn’t notice a bite, you should see a doctor.

Lyme disease can cause great suffering and we should take every possible step to prevent it, while still enjoying our time in nature respectfully.  The fact that parasites like ticks will feed on our blood is a salutary reminder that for all our intelligence, we are still part of an ecosystem, still part of the flow of nutrients through the cycle of life.


About Gary

Lead Instructor at Jack Raven Bushcraft, teaching bushcraft, wilderness and survival skills to groups and individuals.

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