Disease	Signs and symptoms	Diagnosis	Treatment
Lyme disease	Early localized: EM rash at site of inoculation, flulike symptoms Early disseminated: secondary EM lesions, neurologic (meningitis, facial palsy), musculoskeletal (arthralgias and myalgias), and cardiovascular symptoms (temporary atrioventricular block) Late disseminated: encephalomyelitis, polyarticular arthritis, Lyme carditis	Clinical diagnosis for early localized disease Enzyme-linked immunosorbent assay followed by Western blot assay for unclear or later stage diagnosis	Doxycycline 100 mg twice per day or 4 mg per kg in two divided doses for children > 8 years Amoxicillin 500 mg three times per day or 50 mg per kg in three divided doses for children Cefuroxime axetil (Ceftin) 500 mg twice per day or 30 mg per kg in two divided doses for children Azithromycin (Zithromax) 500 mg once per day or 10 mg per kg per day for children IV ceftriaxone (Rocephin) 2 g per day or 50 to 75 mg per kg per day for children used for neurologic manifestations of late disease Duration of therapy:  Early localized: 14 days  Early disseminated: 14 to 21 days  Late disseminated: 14 to 28 days
Rocky Mountain spotted fever	Flulike symptoms with macular rash starting on wrists, forearms, and ankles, becomes petechial	Clinical signs and symptoms including thrombocytopenia and hyponatremia, elevated transaminases, and hyperbilirubinemia IFA is confirmatory but should not delay treatment	Doxycycline 100 mg twice per day or 4 mg per kg for children in two divided doses Chloramphenicol if contraindication to doxycycline Duration of therapy: seven to 10 days
Anaplasmosis and ehrlichiosis	Flulike symptoms with gastrointestinal predominance Rash in up to one-third of patients with ehrlichiosis, particularly children	Clinical signs and symptoms including thrombocytopenia, leukopenia, and elevated transaminases IFA is confirmatory but should not delay treatment	Doxycycline 100 mg twice per day or 4 mg per kg for children in two divided doses Rifampin or chloramphenicol if contraindication to doxycycline Duration of therapy: minimum of 10 days, continue for at least three days after fever subsides
Babesiosis	Nonspecific flulike symptoms; jaundice may be present	Laboratory findings of hemolytic anemia, thrombocytopenia, elevated transaminases Thin blood smear with characteristic “Maltese cross” pattern or PCR	Atovaquone (Mepron) 750 mg twice per day or 40 mg per kg in two divided doses for children plus azithromycin 500 mg on day one followed by 250 mg per day or 10 mg per kg on day one followed by 5 mg per kg per day for children Duration of therapy: seven to 10 days IV clindamycin plus oral quinine and/or exchange transfusion for severe disease
Tularemia	Flulike symptoms, cutaneous eschar at site of inoculation, and painful regional lymphadenopathy	History of exposure to rabbits and other rodents or ticks, leukocytosis Culture is the dianostic standard for diagnosis of tularemia, but has biosafety concerns; PCR or paired serologies may also be used	Intramuscular streptomycin 2 g in two divided doses or 15 mg per kg in two divided doses for children Intramuscular gentamicin or IV 5 mg per kg in two divided doses Duration of therapy: seven to 10 days
Colorado tick fever	Triad of high fever (up to 104°F [40°C]), severe myalgias, and headache; fever is often biphasic; “saddle-back” pattern	Common laboratory findings of leukopenia and thrombocytopenia Reverse-transcriptase PCR or paired sample serologic testing	Supportive care only
Tickborne relapsing fever	Flulike symptoms with high fever in relapsing or remitting pattern	Detection of spirochetes in blood using dark field microscopy or specific staining	Doxycycline 100 mg twice per day or tetracycline 500 mg every 6 hours for adults Erythromycin 500 mg four times per day for pregnant women or 30 to 50 mg per kg in four divided doses for children IV ceftriaxone or penicillin G for patients with central nervous system involvement Duration of therapy: seven to 10 days Jarisch-Herxheimer reactions common with treatment