Tick-borne diseases are a group of infectious illnesses contracted from tick bites. Ticks infected with disease-causing bacteria transmit them to humans when they attach to the skin to feed. In the U.S., the most common tick-borne illnesses are Rocky Mountain spotted fever, ehrlichiosis, Lyme disease and anaplasmosis. These illnesses vary in severity, but all commonly cause fever and headache.
Rocky Mountain Spotted Fever
Rocky Mountain spotted fever is caused by the bacterium Rickettsia rickettsia. The illness typically occurs during the spring and summer months and is most common in the southern Atlantic states. Symptoms typically begin five to 10 days after a bite from an infected tick. Fever, muscle aches, severe headache and nausea and vomiting develop followed by the appearance of a rash. Antibiotics are effective for treating Rocky Mountain spotted fever. Prompt treatment is necessary to prevent complications from this bacterial infection.
Ehrlichiosis
Ehrlichiosis is most commonly caused by the bacterium Ehrlichia chaffeensis, which is transmitted by the Lone Star tick. Common early symptoms include headache, fever, muscle aches and fatigue, which develop within five to 10 days after a bite from an infected tick. Other possible symptoms include joint pain, cough, nausea, vomiting and diarrhea. A skin rash may develop. Ehrlichiosis is treated with antibiotics. The illness is most common in southeastern and southcentral states and most often occurs during the May to July time frame.
Lyme Disease
The bacterium Borrelia burgdorferi causes Lyme disease, which is transmitted by an infected blacklegged tick. Lyme disease typically presents with a skin rash, which begins at the site of the bite and expands outward creating a bull's-eye lesion with a red outer border. Similar smaller skin lesions may develop. Within a few days to a few weeks after the appearance of the skin lesions, other symptoms develop as the bacteria spread through the body. Symptoms include fever, fatigue, headache and muscle and joint aches. Meningitis, heart rhythm abnormalities and nerve complications may develop. Left untreated, most people will go on to have recurring episodes of joint pain and swelling; the knees are most commonly affected. Antibiotics are used to treat Lyme disease. They are most effective in the early stage of the illness. Lyme disease is most common in the northeastern states, although cases occur throughout the U.S.
Anaplasmosis
The bacterium Anaplasma phagocytophilum causes anaplasmosis, which is transmitted by the blacklegged tick and the western blacklegged tick. Symptoms including fever, vomiting, headache and body aches typically develop five to 21 days after a bite from an infected tick. Unlike other tick-borne diseases, anaplasmosis does not typically cause a skin rash. The illness is treated with antibiotics. The Centers for Disease Control and Prevention reports most cases of anaplasmosis occur in New York, New Jersey, Connecticut, Wisconsin and Minnesota.
References
- Centers for Disease Control and Prevention: Rocky Mountain Spotted Fever, Questions and Answers
- Merck Manual: Rocky Mountain Spotted Fever
- Centers for Disease Control and Prevention: Ehrlichiosis, Questions and Answers
- Merck Manual: Ehrlichiosis
- Centers for Disease Control and Prevention: Lyme Disease
