September 10, 2010
Dear Mayo Clinic:
I've found numerous ticks on me throughout the summer but none have caused any problems. What should I look for when I know I've been bitten by a tick?
Spring and summer months are when people most frequently develop infections related to tick bites. Although tick bites are usually harmless, ticks can pass on infectious organisms that cause serious illnesses. Left untreated, these infections can even be life-threatening. Fortunately, antibiotic treatment is usually successful, particularly when treatment is started early.
If a tick bites you, it's important to be aware of the signs and symptoms associated with tick-related diseases. Two that are more commonly recognized are Lyme disease and Rocky Mountain spotted fever. Although each of these illnesses can mimic or appear to be related to another condition, they can both produce a telltale rash.
Lyme disease, the most commonly reported tick-borne infection in the U.S., is transmitted by the deer tick. Deer ticks are found throughout the U.S., especially on the East and West coasts and in Wisconsin and Minnesota. Only a minority of deer ticks carry the infectious agent, but if an infected tick bites you, the longer it's attached to your skin, the greater the risk you'll be infected. Several days to a few weeks after the bite, a red, circular-shaped rash may develop around the bite and flu-like signs and symptoms may follow.
When caught early, oral antibiotics often prevent complications. The antibiotic doxycycline generally is the drug of choice. Amoxicillin and cefuroxime also are effective.
If Lyme disease isn't treated and is allowed to progress, multiple problems may develop. Arthritis may develop within several months to two years of the bite. Facial paralysis (Bell's palsy), heart problems and neurological symptoms also may occur within several months of being bitten. Depending on the symptoms, intravenous (IV) antibiotics may be needed.
Rocky Mountain spotted fever is the second most common tick-borne infection in the U.S. It's transmitted by several types of ticks, including the wood tick and American dog tick. Rocky Mountain spotted fever is found throughout the country, but it's most common in the eastern U.S.
Signs and symptoms of this illness can be flu-like at first. During the first week, a red rash may appear on the wrists and ankles and eventually spread up the arms and legs to the chest. A mild case of the infection that's treated promptly with antibiotics typically causes few problems. However, left untreated, Rocky Mountain spotted fever may cause serious complications, such as heart, lung or kidney failure, or a brain infection called encephalitis, which can lead to a coma. It can be a severe illness — especially in older adults — and is even fatal in a small percentage of cases.
Less familiar tick-borne illnesses can also pose significant risks if not recognized and treated. The following illnesses have numerous signs and symptoms in common, including flu-like symptoms, profuse sweating and weight loss. Antibiotics are generally recommended for treatment of each disease:
If you've been bitten by a tick and develop a rash, fever, stiff neck, muscle aches, joint pain, swollen lymph nodes or flu-like symptoms, see your doctor. Generally, the earlier tick-borne illnesses can be identified and treated, the better.
— Alan Wright, M.D., Infectious Diseases, Mayo Clinic, Rochester, Minn.