Lyme Disease

Lyme disease is an infection caused by the bacteria Borrelia burgdorferi, spread by the bites of infected ticks.  The infection is spread from the saliva of ticks which feed on the blood of host animals, including humans,

 

Epidemiology

Ticks can be found in temperate environments, in almost every country in the Northern Hemisphere.  In the UK there are an estimated 2000-3000 cases reported annually. (1)  In the US figures are around 300,000 cases per year. (2)

Ticks cling to branches and latch onto passing animals to feed on their blood.   In the UK deer are the most widely known host but all small mammals and bird can host infected ticks.  It is not currently thought that the infection is actually spread by deer, rather smaller mammals such as mice (3) and birds.

As such any woodland and grassland area is capable of hosting infected ticks.

Sheep Tick Credit:  James Lindsey at Ecology of Commanster [CC BY-SA 2.5

Sheep Tick

Credit:  James Lindsey at Ecology of Commanster [CC BY-SA 2.5

Engorged Sheep Tick Credit:  Richard Bartz - CC-BY-SA 2.5

Engorged Sheep Tick

Credit:  Richard Bartz - CC-BY-SA 2.5

 

Signs and Symptoms

Erythema Migrans Credit:  James Gathany / Centers for Disease Control and Prevention's Public Health Image Library

Erythema Migrans

Credit:  James Gathany / Centers for Disease Control and Prevention's Public Health Image Library

Finding a tick on your body does not mean that you will have caught Lyme disease;  it is known to take 36-48 hours of attachment for the bacteria to transfer from the tick to the host. (4)  If the tick can be removed within 24 hours, infection is unlikely.(5) 

The most common sign of infection is a red target-like rash called erythema migrans which begins at the site of a tick bite about a week after it has occurred.  The rash is not usually itchy or painful, however, approximately 25–50% of infected people do not develop a rash.

Early symptoms within 3-30 days include (6)

  • Fatigue
  • Chills
  • fever
  • Headache
  • Muscle and joint aches
  • Swollen lymph nodes

 

Days to months after the bite, late symptoms may develop (6)

  • Severe headaches and neck stiffness
  • Additional EM rashes on other areas of the body
  • Arthritis with severe joint pain and swelling, particularly the knees and other large joints.
  • Facial palsy (loss of muscle tone or droop on one or both sides of the face)
  • Intermittent pain in tendons, muscles, joints, and bones
  • Heart palpitations or an irregular heart beat (Lyme carditis)
  • Episodes of dizziness or shortness of breath
  • Inflammation of the brain and spinal cord
  • Nerve pain
  • Shooting pains, numbness, or tingling in the hands or feet
  • Problems with short-term memory

 

Treatment

Prophylactic treatment of a single dose of doxycycline may be used to prevent development of infection if the removed tick was full of blood, but is not generally recommended since development of infection is rare.   If signs and symptoms develop a 2-3 week course of doxycycline, amoxicillin, or cefuroxime may be prescribed.  (7)   Early treatment is usually successful. (8)

Late stage treatment typically requires intravenous ceftriaxone or cefotaxime and doxycycline as alternatives. (9)

Some casualties with late stage symptoms develop can develop long term fatigue, muscle and joint pain and even congestive heart failure. (10)   The lesson here?   If in doubt – get checked out.

 

Prevention

Common sense dictates that avoiding wooded or grassy areas, especially during summer months when foliage is dense and animal life is more active is the best way to reduce the likelihood of infection.   If you are to encounter these environments, several strategies can reduce the risk of infection.

  • Avoid dense foliage and long grass by sticking to footpaths.
  • Cover arms and legs to prevent tick form latching onto your skin when brushing through long grass and foliage.
  • Light clothing may make it easier to spot ticks on your clothes.  These need to be removed as they may migrate under cuffs, collars and hems.
  • Permethrin insecticide can be sprayed onto clothing which may kill insects and arachnids, including ticks, on contact.
  • DEET based insect repellents can be applied to the skin – especially around collars, cuffs and hems.
  • Inspect your skin for ticks including your head, neck and skin folds, armpits and groin.  You may need a willing accomplice and repay the favour.
  • Wash clothing in a high heat and tumble dry to kill any ticks you have brought home with you.
  • Remove any ticks you find promptly.

 

Tick Removal

Tick sizes - Egg, Larvae, Adult Male,Adult, Female. (L-R) Credit:  CDC - https://www.cdc.gov/mmwr/volumes/65/rr/rr6502a1.htm

Tick sizes - Egg, Larvae, Adult Male,Adult, Female. (L-R)

Credit:  CDC - https://www.cdc.gov/mmwr/volumes/65/rr/rr6502a1.htm

Ticks are small!   Depending upon the stage of life cycle from larva to adult, ticks can be less than a millimeter in size so finding them can be difficult.

No ‘traditional’ method of tick removal is known to be effective; using oil, petrol or Vaseline etc. can kill the tick, forcing it to vomit while drinking your blood, increasing the likelihood of infection.  Using the flame from a cigarette lighter or the ember of a cigarette itself is more likely to cause a burn to your skin with a dead tick stuck in it.

A number of dedicated tick removal tools exist which all work equally well.   Tweezers can also be used as long as:

  1. the tick is grasped at the head – grasping the body is likely to squeeze the tick’s stomach contents back into and
  2. as close to the skin as possible.   The further up the body of the tick you pull, the more you are likely to leave behind.

 

 

Summary

  • Reduce the risk of infection by being aware of your environment and preparing properly with appropriate clothing and chemical agents.
  • Check yourself diligently after exposure to these environments.
  • If found, remove the tick using a dedicated tool or tweezers.
  • Being bitten does not mean you will have caught Lyme disease.   Attachment of 36-48 hours is usually required.
  • If you are infected, the flu-like symptoms associated with early development do not show immediately.   If you experience these symptoms up to 30 days after being in a tick-likely environment, see your GP.
  • Prevention is better than cure and treatment works best when delivered early.

 

References

  1. http://www.wired-gov.net/wg/wg-news-1.nsf/0/73C50674932B7389802578730037AFFF?OpenDocument accessed 12/02/2017
  2. https://www.cdc.gov/lyme/stats/index.html accessed 12/07/12
  3. James G. Donahue, JG.  Piesman, J.  Spielman, A(1987)  “Reservoir Competence of White-Footed Mice for Lyme Disease Spirochetes”.  American Journal of Tropical Medicine and Hygiene 1987 36:92-96
  4. https://www.cdc.gov/lyme/transmission/index.html accessed 12/07/2017
  5. Piesman J, Dolan MC (2002). "Protection against Lyme disease spirochete transmission provided by prompt removal of nymphal Ixodes scapularis (Acari: Ixodidae)". Journal of Medical Entomology. 39 (3): 509–12.
  6. https://www.cdc.gov/lyme/signs_symptoms/index.html accessed 12/02/2017
  7. Shapiro, ED (2014). "Clinical practice. Lyme disease." The New England Journal of Medicine. 370 (18): 1724–31.
  8. Krause PJ, Foley DT, Burke GS, Christianson D, Closter L, Spielman A (2006). "Reinfection and relapse in early Lyme disease". American Journal of Tropical Medicine and Hygiene. 75 (6): 1090–94
  9. Wright WF, Riedel DJ, Talwani R, Gilliam BL; Riedel; Talwani; Gilliam (2012). "Diagnosis and management of Lyme disease". American Family Physician. 85 (11): 1086–93.
  10. Klempner MS, Hu LT, Evans J, et al. (July 2001). "Two controlled trials of antibiotic treatment in patients with persistent symptoms and a history of Lyme disease". New England Journal of Medicine. 345 (2): 85–92.