What is a disease caused by a tick? - briefly
Lyme disease, resulting from infection with the bacterium Borrelia burgdorferi transmitted by Ixodes ticks, is the most common tick‑borne illness. Other significant tick‑transmitted infections include Rocky Mountain spotted fever, ehrlichiosis, and babesiosis.
What is a disease caused by a tick? - in detail
Tick‑borne illnesses comprise a range of infections transmitted when an infected arthropod attaches to the skin and feeds on blood. The most common agents, their vectors, clinical features, diagnostic methods, and recommended therapies are outlined below.
Lyme disease is caused by the spirochete Borrelia burgdorferi and is transmitted primarily by the black‑legged tick (Ixodes scapularis in eastern North America and Ixodes pacificus on the West Coast). Early manifestations include erythema migrans, fever, headache, and fatigue. If untreated, the infection may progress to arthritis, carditis, or neurological deficits. Diagnosis relies on a two‑tier serologic algorithm (ELISA followed by Western blot). Doxycycline for 10–21 days is the first‑line treatment; alternatives include amoxicillin or cefuroxime.
Rocky Mountain spotted fever results from Rickettsia rickettsii infection, with the American dog tick (Dermacentor variabilis) and the Rocky Mountain wood tick (Dermacentor andersoni) as principal vectors. Typical signs are sudden fever, severe headache, rash that begins on wrists and ankles and spreads centrally, and possible gastrointestinal symptoms. Prompt administration of doxycycline (100 mg twice daily for 7–14 days) is essential; delayed therapy increases mortality.
Ehrlichiosis and anaplasmosis are intracellular bacterial diseases caused by Ehrlichia chaffeensis and Anaplasma phagocytophilum, respectively. The lone star tick (Amblyomma americanum) transmits ehrlichiosis, while the same Ixodes species that spread Lyme disease also carry anaplasmosis. Patients present with fever, chills, myalgia, leukopenia, and elevated liver enzymes. Polymerase chain reaction (PCR) or serology confirms infection; doxycycline for 5–14 days is effective.
Babesiosis, a malaria‑like protozoal infection, is caused by Babesia microti and transmitted by the same Ixodes ticks that spread Lyme disease. Hemolytic anemia, fever, chills, and thrombocytopenia characterize the disease. Diagnosis combines microscopic examination of blood smears, PCR, and serology. Treatment combines atovaquone and azithromycin; severe cases require clindamycin plus quinine.
Powassan virus, a flavivirus, is transmitted by Ixodes ticks in the northeastern United States and parts of Canada. Neurological involvement, including encephalitis and meningitis, may develop within days of the bite. No specific antiviral therapy exists; supportive care in an intensive setting improves outcomes. Diagnosis uses reverse‑transcriptase PCR or serologic testing for IgM antibodies.
Tularemia, caused by Francisella tularensis, can be spread by the dog tick (Dermacentor variabilis) and the rabbit tick (Haemaphysalis leporispalustris). Presentation includes ulceroglandular lesions, fever, and lymphadenopathy. Streptomycin or gentamicin constitutes the preferred therapy; doxycycline serves as an alternative.
Tick‑borne encephalitis (TBE) is a flaviviral disease transmitted by Ixodes ricinus in Europe and Ixodes persulcatus in Asia. The biphasic course begins with nonspecific flu‑like symptoms, followed by neurological signs such as meningitis, encephalitis, or myelitis. Diagnosis utilizes PCR and IgM/IgG serology. No antiviral drug is approved; management focuses on reducing cerebral edema and providing supportive care. Vaccination is available in endemic regions.
Prevention strategies include avoiding tick habitats during peak activity, wearing long sleeves and pants, applying permethrin‑treated clothing, using EPA‑registered repellents containing DEET or picaridin, and performing thorough body checks after exposure. Prompt removal of attached ticks with fine tweezers, grasping close to the skin and pulling steadily, reduces transmission risk.
Collectively, these diseases illustrate the diverse pathogens that ticks can harbor, the geographic variability of risk, and the importance of early recognition, accurate laboratory confirmation, and timely antimicrobial or supportive therapy.