Discussion 3: Lyme borreliosis

For this discussion we were asked to wrote about an emerging infection disease.  An emerging infectious disease is one that is relatively new, or one that is newly more active.  Some of the diseases listed as emerging are actually ones that we have known about for a long time, but that are simply now infecting many more people.  One such disease is Lyme borreliosis.  Lyme disease is caused by bacteria that is transmitted to people by Western black legged ticks, and deer ticks.

The surge in incidence of Lyme disease my be linked to the protection of white tailed deer.  After white tailed deer became protected, their numbers began to rise.  Now they are much more prevalent than they were just fifty years ago, and many have moved into suburban neighborhoods where they eat landscapes and drop off ticks.  The deer serve as a reservoir for Lyme disease.  Infected deer, infect the ticks that they then leave behind.  When these ticks bite humans, they contract Lyme disease as well.  A comparison of maps showing the dispersion of Lyme disease carrying ticks, and white deer populations is indicative of this connection



The similarity in range is clear between the the tick distribution map, and the white tailed deer population dispersal map from 1982.  Now look at the population growth of white tailed deer as shown in this population map from 2008 and you can see how there could be a parallel increase in deer tick populations.

This information is only applicable to the United States, but Lyme disease also occurs in parts of Europe and Asia.

When a person contracts Lyme disease, it is typically identified by the symptoms, combined with likelihood of exposure.  As previously mentioned, with deer moving into more urban areas the likelihood of exposure is growing.  Blood tests can also be used to determine Lyme infection.  Patients typically present with a distinct rash that spreads outward in a ring shape from lesions.  This is accompanied by fever, aches and other flu-like symptoms.  Occasionally the rash does not occur, and in people with more melanin it can be hard to spot.  After a couple of weeks the rash will subside.  As the disease progresses it attacks the joints and causes severe stiffness and pain.  Further complications including ones involving the central nervous system and Bell's Palsy can develop as much as months later if it is left untreated.

There is however, some good news about Lyme disease.  If ticks are removed within the first 36 hours it is possible to prevent Lyme disease.  Although ticks are tiny, they can be spotted and removed through vigilance.  If Lyme disease is contracted, because it is caused by a bacteria, it is fully treatable with a three week course of antibiotics.  It is best to start antibiotics as soon as possible to prevent progress of the disease and to minimize complications.  Lyme disease is also not transferable directly between humans, which helps to limit it's spread.  For those who do contract Lyme disease, there is an online support organization called Lyme Buddies that provides support and information.  The organization also sponsors a 5K to raise awareness of Lyme Disease.  The even better news is that Lyme disease can be prevented by making sure to check for ticks after being outside in areas where they are likely to be present, and through the use of insect repellent and tick habitat management.

Emerging infectious diseases are something of which we all should be aware.  Bacteria and viruses mutate at a much faster rate that humans because their life cycles are much shorter, so we will continue to face new disease threats.  It is important however to make sure we continue to be aware of diseases that have made huge impacts in the past, but that have been mostly contained, although not eradicated for many years. Yellow fever has had devastating effects on populations in the past, but is relatively unknown today, despite the fact that authorities continue to mandate that even a single case  be treated as an epidemic.  Epidemiological awareness is something that is key to ultimate human survival and well being.



Sources:
Lyme Borreliosis (Lyme Disease). WHO. http://www.who.int/ith/diseases/lyme/en/. Accessed 25 April, 2013
Lyme Disease. CDC. http://www.cdc.gov/lyme/. Accessed 25 April 2013.
Lyme Disease. Targret Woman. http://www.targetwoman.com/articles/lyme-disease.html. Accessed 25 April 2013.