As the summer rolls in, my schedule in primary care starts to shift yet again, as it seems to with the seasons. Not only do I see more acute injuries, the rise in patients coming in for tick bite evaluations rises as well.
In Pennsylvania, Lyme disease is very common, as we are in an area that is endemic with ticks that can transmit Lyme disease. We are also surrounded by woods and mountains where ticks hide.
In primary care and urgent care, tick bites are very common chief complaints. These visits can be apprehensive for patients, as many patients know a family member or friend with Lyme disease. Many patients may be misinformed with data retrieved from various websites or word of mouth. Not only is evidence based medicine of utmost important in these encounters, patient education is also paramount.
This article will review the causative agent for Lyme disease, discuss how to take a history in regards to a tick bite and discuss criteria for prophylaxis of tick bites. The manifestations, history and physical, symptoms, and treatment of Lyme disease will be discussed elsewhere.
Lyme disease is the most commonly encountered tick associated disease in the United States. The disease is transmitted by the Ixodes scapularis or deer tick. The spirochete Borrelia burgdorferi is the causative agent for symptoms. Other types of ticks may be causative in other areas of the United States. Students should know the scientific name for deer ticks and the spirochete that causes disease, as these are commonly encountered test questions.
When encountering a patient with a tick bite, the history is very important. The first step is understanding the geography, tick distribution, and local Borrelia burgdorferi infection rate. Endemic areas can include New England, Pennsylvania, and Mid-Atlantic states.
Patients should be questioned about the nature of the tick. Some patients with previous experience with ticks or who are active outdoors may be trained to identify ticks. The patient should be asked if the tick was a deer tick or Ixodes Scapularis species. Patients may bring in ticks for identification, which may be helpful. Identifying if the tick is larval, nymphal, or adult is helpful as well (Hu, 2018), as about 90% of cases are transmitted during the nymph life cycle.
Another key important point is how long the tick has been attached. Depending on the location of the tick bite, this may be obvious, or may be unknown. Patients with bites on the scalp, posterior neck, groin region, or back may not be sure of duration of attachment.
The size of the tick or insect should be clarified with the patient. Patients may confuse other insects such as lice, fleas, or other bugs with tick bites. In general, nymphal deer ticks are very small, making them hard to spot. Larger ticks are likely to be adult ticks, or even other bugs.
Another point of discussion is whether the tick was attached or engorged. As discussed above, length of attachment is very important. Ticks that are simply walking over a patient’s skin or are brushed off, are not capable of transmitting Lyme disease. An engorged tick is more difficult to remove.
The clinician should also ask the patient about methods to remove the tick. Some patients may go to extremes to try to remove the tick prior to an office appointment. Technique should be discussed and the patient should be asked whether they were able to remove all of the tick parts. As discussed above, bringing the tick in for analysis can be helpful for the trained eye.
In terms of removal of a tick, the patient can be educated on proper methods. Tweezers or other instruments are useful and should be used to grasp the tick as close to the skin as reasonable. The remover should pull straight up and avoid using any twisting motion. The tick should not be squeezed or crushed. Once removed, the skin should be examined for any retained mouth or leg parts and then disinfected and cleaned thoroughly (Hu, 2018).
Once the history is taken above, the physical exam should begin with the clinician examining the skin closely. The tick bite should be probed. Ticks present on skin or brought in for analysis should be analyzed. Once tick removal is performed, the area should be observed as above.
The question remains, who should undergo prophylaxis for Lyme disease?In the patient with evidence of a tick bite but no active signs or symptoms of Lyme disease, what indications are there for medical treatment to try to prevent Lyme disease?
The clinician should spend time working toward educating the patient on the indications to undergo prophylaxis. Evidence based medicine should be utilized to provide scientific based care to patients and patients should be cautioned not to believe every source of information available through social media or internet sources.
The Infectious Disease Society of America has put together guidelines related to the prophylaxis of Lyme Disease. As always, the individual patient presentation, patient goals, geography of the region, provider gestalt, and other factors should contribute to the decision making.
Patients can be considered for prophylaxis if they meet certain criteria. First, the tick should be identified as a deer tick. For patients who present with positive identification of another insect or different type of tick, reassurance should be provided. Secondly, the tick should be attached for greater than 36 hours. For patients not knowing length of attachment, this can be tricky. Thirdly, the timeline of prophylaxis should be within 72 hours of the tick bite. The local rate of infection of ticks with Borrelia burgdorferi should be greater than 20%.
In patients not meeting all of these categories, reassurance as well as education about the signs and symptoms of Lyme disease can be discussed. For patients meeting all of the above categories, doxycycline 100 mg two tablets as a one time dose is the preferred prophylaxis. No other anti-biotic has been approved for prophylaxis. Patients should be encouraged to start it as soon as possible, but still monitor for signs and symptoms of Lyme. Patients should be encouraged to wear tick repellant, do regular tick checks, and be cognizant about the disease in general.
Chang, F.B. (2016). Lyme Disease. The Five Minute Clinical Consult. Wolters Kluwer.
Hu, L. (2018). Evaluation of a tick bite for possible Lyme Disease. UpToDate. Date of Access 29 May 2018.
Wormser, GP (2006). The clinical assessment, treatment, and prevention of lyme disease, human granulocytic anaplasmosis, and babesiosis. Clinical Infectious Disease; 43(9): 1089.
This article, blog, or podcast should not be used in any legal capacity whatsoever, including but not limited to establishing standard of care in a legal sense or as a basis of expert witness testimony.No guarantee is given regarding the accuracy of any statements or opinions made on the podcast or blog.