By VickieMarie Cloutier, MD, FAAFP
Tick-borne diseases in the United States are transmitted via Ixodes scapularis and Dermacentor variabilis and include Lyme disease, Rocky Mountain spotted fever (RMSF), ehrlichiosis, anaplasmosis, babesiosis, tularemia, Colorado tick fever (viral) and tickborne relapsing fever. The most common is Lyme disease. All start with flu-like symptoms – muscle and joint aches, fever, and some have a rash.
Lyme rash starts at the tick bite site. Unfortunately, testing is not usually positive directly after the bite. Treat with doxycycline due to symptoms and signs.
RMSF starts with flu-like symptoms and a macular rash on wrists, forearms and ankles. Clinical tests can show low sodium, elevated liver transaminases, high bilirubin and low platelets, which cause the petechial rash.
Anaplasmosis and ehrlichiosis also start with flu-like symptoms but have a gastrointestinal predominance with a rash in up to a third of patients. Lab results can show low platelets, high liver transaminases, low white blood count. Treatment again is doxycycline.
Babesiosis can present with hemolytic anemia, low platelets and elevated liver transaminases.
Tularemia presents with flu-like symptoms. Cutaneous eschar can be present at the site of a tick bite (inoculation) with painful swollen lymph nodes. Often there is a history of exposure to rabbits. Lab tests may show elevated white blood cell count. This is treated with intramuscular antibiotics for 7 to 10 days.
Colorado tick fever presents with a high fever (up to 104 degrees), muscle pain and a headache. Lab results can show low white count and platelets. There is no antibiotic, just supportive care.
Tickborne relapsing fever presents with flu-like symptoms and a high fever that relapses. Lab testing is for spirochetes in blood using dark field microscopy. Treatment is antibiotics, including doxycycline.
Much of the information for this article is obtained from the American Family Physician Volume 101 Number 9 May 1, 2020.