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Tick Borne Illness | Part 1

Solomon Behar, MD and Jason Woods, MD
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22:07

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Tick borne illnesses are common in the United States and tend to have a geographic distribution specific to the distribution of the tick vector. Bites commonly in the spring to early fall months when ticks are active and seeking out blood meals. The most common tick-borne illness in the US is lyme disease but other diseases include Rocky mountain spotted fever, Babesiosis, Tularemia, Ehrlichia, and Tick paralysis. Sol chats with Jason woods to discuss clinical presentation, treatment, and prevention of these tick borne diseases.

Pearls:

  • The treatment for Rocky Mountain Spotted fever(RMSF) often needs to be started empirically as early treatment prevents morbidity. Doxycycline is the agent of choice regardless of age of the patient.

  • Patients should be instructed to check for ticks after outdoor activities and ticks  should be removed with tweezers griping right at the level of the skin.

  • Ticks need to be present on the skin for 36 hours to transmit Lyme though RMSF can be transmitted much quicker.

 

  • How can ticks be identified? In the US most insects that bite and attach to a human host are ticks. They can start as small as a pinhead. The ticks when very small and flat have just recently attached and not yet started to feed. As the feed on blood they become engorged.

  • How important are ticks for human illness? In the US ticks are the most important arthropod vector of disease and worldwide are the second most important after mosquitos.

  • What should you do if a patient presents with the tick still attached? The tick should be removed with tweezers griping right at the level of the skin. The skin will tent up so apply pressure to the surrounding skin with your other hand to make it less painful. The ticks produce a substance called cementum that attaches the ticks head to the skin. After removing the tick carefully inspect to evaluate if any portion of the tick was left behind as they can break apart. A scalpel can be used to remove any remaining part adherent to the skin. Do not perform any of the home remedies that patients may have heard of based on burning or suffocating.

  • What terminology are important for tick borne illnesses? With Lyme disease as an example:

    • Pathogen - Borrelia burgdorferi is the bacteria that causes human illness.

    • Vector - The tick is the vector that transmits the pathogen to humans.

    • Reservoir - White-footed mice are the reservoir of the pathogen which is transmitted by the vector from the mice to humans.

    • Host - Both humans and mice are hosts of tick who consumes blood.

  • When are ticks most infectious? Ticks are most infectious after eating their first meal from an infected host. The bacteria is initially dormant in the tick and becomes more infectious with time. As a rule of thumb it is rare for ticks to transmit disease without being present on the skin for at least 36 hours.

    • For this reason once daily tick searches can be done to significantly reduce the risk of getting Lyme from ticks.

    • Rocky mountain spotted fever can be transmitted in as little as 6 hours

  • What are common tick borne illnesses? Lyme is the most common in the US though it is not present in all parts. Lyme is primarily in the Northeast though it can be endemic through parts of the sound and northern Midwest. This has to do with the distribution of the white-footed mouse which is the reservoir.

  • What symptoms should we be looking for in Lyme? If the tick is still present there would typically not be symptoms though it would be possible to have the erythema migrans rash around the site of the tick.

  • What does erythema migrans look like? This is a targetoid rash with a red circular ring with central clearing. It may not have the central clearing and can also have a double ring.

  • What happens after the erythema migrans rash? The initial rash occurs about a week after exposure.

    • After the initial lesion multiple erythema migrans lesions can occur indicating hematogenous spread. Other early symptoms can include malaise, arthralgia, myalgia, and fever.

    • A few weeks after the initial infection a cranial nerve palsy like Bell's palsy can occur as can aseptic meningitis.

  • What is the diagnostic testing is used? Regardless of the stage of the disease serology on the blood is the best test. Organisms will be difficult to recovered from CSF or joint fluid. Serology is better than PCR for diagnosis.

  • When is prophylaxis indicated? Prophylaxis may be indicated when a tick has been present for at least 36 hours, antimicrobials can be started within 72 hours of tick removal, the tick is one which would be associated with Lyme transmission, and Lyme is locally endemic. Prophylaxis is with a single dose of Doxycycline  4mg/kg up to 200mg for those eight years of age or older. There are not IDSA recommendations for prophylaxis in younger children.

    • Wormser GP, et al. The clinical assessment, treatment, and prevention of lyme disease, human granulocytic anaplasmosis, and babesiosis: clinical practice guidelines by the Infectious Diseases Society of America. Clin Infect Dis. 2006 Nov 1;43(9):1089-134. PMID 17029130

  • What is treatment for Lyme? Treatment is indicated when symptoms are present. This can include the erythema migrans rash or or any of the other symptoms. The treatment is typical doxycycline though amoxicillin and cefuroxime are approved for children under eight. The treatment course is 14-21 days.

    • Some people may get transiently worse with treatment, the Jarisch-Herxheimer reaction, this is mediated by byproducts of killed bacterial.

  • What is Rocky Mountain Spotted Fever (RMSF)? RMSF is caused by Rickettsia rickettsii carried by Dermacentor species of ticks.

  • How does RMSF present? The presentation can be a bit tricky as many symptoms can be quite generic such as fever, headache, myalgia and nausea.

    • In more severe cases there can be  thrombocytopenia, hepatic dysfunction, pneumonitis, carditis, encephalopathy, and the rash that it is known for. These symptoms are caused by the vascular invasion and vasculitis.  

  • What does the rash look like? The rash can be blanching and macular but the board question would be petechiae on the wrists and ankles that moves from peripheral to central.

  • What is the time course? Symptoms may start one to two weeks from exposures.  From that point that symptoms start some will have have just fever and myalgia while others will quickly progress to the more severe symptoms.

  • What time of year does this occur? Most tick borne illness happens based on when people are exposed to ticks and the life cycle of the ticks. These typically means cases are seen in late spring, summer and early fall.

  • How is RMSF diagnosed? Like Lyme Serology is the best test. It is a gram negative intracellular bacillus. Being intracellular and not present in large numbers it is hard to detect directly. Serology is not positive immediately and so many cases are treated based on clinical presentation. Hyponatremia, hepatic dysfunction and thrombocytopenia on lab work may suggest the diagnosis and be indications for empiric treatment.

  • What is the treatment? The treatment at any age is doxycycline. The course is a minimum of three days and resolution of fever for about 48 hours.

  • What other tick borne illness should we know about? Anaplasmosis and Ehrlichiosis both can present with fever, myalgia and malaise. Anaplasmosis is found more in New England, Minnesota and Michigan while Ehrlichia is distributed in a similar distribution to RMSF. The treatment is the same as other tick borne illnesses with doxycycline.

  • *Editor’s note: Further reading and maps of distribution of these illnesses can be found via the CDC. Tickborne Disease of the United States.

  • What is Babesiosis? Babesiosis is caused by an intracellular parasite and follows a similar geographic distribution to Lyme. Many people who are infected may be asymptomatic though it can cause flu like illness, malaria like illness with hemolysis and a petechial rash. It may be detected on a blood smear done for other reasons. The treatment is Clindamycin and Quinine.

  • What is tularemia? This is a rare condition that can present with a variety of symptom patterns it can present with fever and malaise. The illness can be tickborne but can also be transmitted through direct inoculation and inhalation. Because of the inhalation mechanism of transmission it is considered a category A bioterrorism agent. There are a variety of treatment options including doxycycline, ciprofloxacin, gentamicin and streptomycin.

  • *Editor’s note: There are a variety of presentation depending on mechanism of exposure including lymphadenopathy, oculoglandular, oropharyngeal, pneumonic or typhoidal

  • How can we prevent tick borne illness? Clothing that covers as much skin as possible can help prevent ticks from attaching. After outdoor activities children should be checked for ticks including the scalp and ticks should be removed as soon as possible. DEET is effective for preventing ticks. DEET up to 35% is recommended to prevent tick borne illness.

  • *Editors note: The AAP recommends that repellents 30% DEET or less for children and not to use under 2 months of age.

  • What is tick paralysis? This is caused primarily by dog ticks and Rocky Mountain Wood ticks. The paralysis is caused by a neurotoxin released by a female tick has prolonged attachment. The paralysis is classically described as a quickly ascending paralysis. The treatment is removal of the tick which can lead to resolution of symptoms in hours to days.

stacie o., 9692404 -

There is a painless way to remove the tick in its entirety. Use a slight moisted q-tip make tight counter clockwise circles at the head of the tick. The tick will rotate partially, keep circling the head it will release or ba k out of the patient on its own. I believe can view on demonstration on YouTube.

Mike W., MD -

Thx Stacie for the tip!
M

Erin B. -

Is there a benefit to removing any small remaining parts remaining in the skin after removal? Or is there any harm in leaving it?

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The Blood Meals Full episode audio for MD edition 207:18 min - 97 MB - M4AHippo UC RAP July 2018 Written Summary 364 KB - PDF

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