HEALTH
Public health efforts have effectively raised awareness about Lyme disease (Borrelia burgdorferi) and the best strategies to reduce exposure to potentially infected blacklegged ticks (Ixodes scapularis). The CDC recommends specific sprays, repellants, tick-repellant clothing, and prevention strategies for pets, homes, schools, etc. At the end of a long day, though, don’t forget the most important preventative measure – daily skin checks to allow for prompt removal of any ticks. Experimental transmission studies have reinforced the effectiveness of daily skin checks and prompt tick removal to reduce the transmission of disease from potentially infected ticks.
This is because the risk of transmission of most Ixodes scapularis-borne pathogens, including Lyme disease spirochetes, increases with the length of time (number of days) infected ticks are allowed to remain attached. In other words, if you find an attached tick at the end of the day, the chances that the tick has had enough time to transmit disease are much lower than if it had been feeding for days. And practically speaking, you can avoid running to the doctor in many cases considering the CDC recommends watchful waiting for 30 days and calling your doctor if you develop a rash, fever, fatigue, headache, muscle pain, or joint swelling/pain. In most cases, the tick must be attached for 36-48 hours or more before Lyme disease can potentially be transmitted. And don’t forget that not every attached tick will carry Lyme disease; generally, 15-20% of nymphs and 50% or more of adult females are infected with Lyme disease spirochetes. Keep in mind that if you are tested too soon with blood work after removing a tick, your body may not have had enough time to build an immune response (develop antibodies to the disease), thus results can be falsely negative because the test is based on identifying those antibodies.
Diagnosis and potential treatment of Lyme disease depends on a number of factors and is not always straightforward. I think it is important for patients to know that doctors cannot easily start the process of diagnosing potential Lyme disease if there was never any identifiable tick present in otherwise asymptomatic patients. This would lead to a lot of unnecessary testing. The only physical exam finding that is a slam dunk and allows for doctors to begin treatment immediately is the presence of a classic erythema migrans rash; your doctor may still want to obtain confirmatory blood work. Otherwise, any reported symptoms or physical findings are considered within the clinical context, and further testing can be carried out if deemed appropriate. Doctors must follow very specific guidelines with regard to diagnosis, including proper interpretation of blood work in the context of the patient's specific history (and time course). In general, the CDC does not recommend taking antibiotics after tick bites to prevent tickborne diseases. Rather observing for symptoms within 30 days is the standard of care (rash, fever, fatigue, headache, muscle pain, joint swelling/pain). Only in certain circumstances is a single dose of preventative doxycycline appropriate. There are very stringent guidelines for this type of treatment, however: an engorged Ixodes blacklegged tick removed within the last 72 hours from a patient living in a Lyme-endemic region.
To learn about tick identification, removal, and potentially having it tested through an approved lab, the CDC and RI Department of Health (and approved affiliates) offer helpful resources.
• Lyme Disease | Lyme Disease | CDC (https://www.cdc.gov/lyme/)
• Lyme Disease: Department of Health (ri.gov) (https://health.ri.gov/diseases/ticks/?parm=68)
• TickEncounter (uri.edu) (https://web.uri.edu/tickencounter/)
Bottom line:
Check for ticks every day. If you find one, put it in a jar or bag, label with the date, and consider having it tested (through TickEncounter, etc). Go to one of the websites above to see if it was an Ixodes scapularis blacklegged tick (many pictures available). If so, and it was engorged, call your doctor to get tested. If it was not an Ixodes or not engorged, monitor for symptoms. If you develop the classic bull’s eye rash (erythema migrans), get tested. Otherwise, keep monitoring. Please note that this advice is specific to Lyme disease, the number one tickborne illness in the eastern United States. Other tickborne illnesses exist and can cause similar presentations (babesiosis, ehrlichiosis more common in this region), but discussion is beyond the scope of this piece.
Resources:
1.) Lantos PM, Rumbaugh J, Bockenstedt LK, Falck-Ytter YT, Aguero-Rosenfeld ME, Auwaerter PG, Baldwin K, Bannuru RR, Belani KK, Bowie WR, Branda JA, Clifford DB, DiMario FJ Jr, Halperin JJ, Krause PJ, Lavergne V, Liang MH, Meissner HC, Nigrovic LE, Nocton JJJ, Osani MC, Pruitt AA, Rips J, Rosenfeld LE, Savoy ML, Sood SK, Steere AC, Strle F, Sundel R, Tsao J, Vaysbrot EE, Wormser GP, Zemel LS. Clinical Practice Guidelines by the Infectious Diseases Society of America, American Academy of Neurology, and American College of Rheumatology: 2020 Guidelines for the Prevention, Diagnosis, and Treatment of Lyme Disease. Neurology. 2021 Feb 9;96(6):262-273. doi: 10.1212/WNL.0000000000011151. Epub 2020 Nov 30. Erratum in: Neurology. 2021 Feb 9;96(6):296. PMID: 33257476.
2.) Pathogen transmission in relation to duration of attachment by Ixodes scapularis ticks. Published in final edited form as: Ticks Tick Borne Dis. 2018 March; 9(3): 535-542. Doi:10.1016/j.ttbdis.2018.01.002
3.) Lyme Disease | Lyme Disease | CDC https://www.cdc.gov/lyme/
