Tick-borne Infections

A tick-borne infection is an infection that is transmitted through the bite of a tick.


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Lyme disease

Rickettsial diseases

Rocky Mountain spotted fever

What Are Tick-borne Infections?

Ticks can spread bacteria or parasites through their bites. A tick becomes infected when it bites an animal, and then the tick can pass the infection to humans when it bites them. Tick-borne infections cannot pass from human to human; they need time in the host * animal to develop.

Ticks can spread a number of different diseases, including Rocky Mountain spotted fever, ehrlichiosis (air-lik-e-O-sis), Lyme (LIME) disease, and babesiosis (bah-bih-sye-OH-sis).

Rocky Mountain spotted fever

Despite its name, most cases of Rocky Mountain spotted fever (RMSF) are not found in the Rocky Mountains but in the southeastern states. It also appears throughout the contintental United States and in Canada, Mexico, and Central and South America. RMSF is one of the most dangerous tick-borne infections because it can be difficult to diagnose and has severe complications. Caused by the Rickettsia rickettsii (rih-KET-see-uh rih-KET-see-eye) bacterium, the disease spreads to humans through bites from the wood tick, dog tick, and Lone Star tick.

Symptoms of RMSF include high fever, headache, aching in the muscles, nausea (NAW-zee-uh), vomiting, and diarrhea (dye-uh-REE-uh). A rash may appear first at the wrists, ankles, palms, and soles and then on the forearms, neck, face, and trunk. RMSF is fatal in about 5 percent of cases. This may be due to delays in diagnosing and treating the disease.


Several types of bacteria in the genus Ehrlichia (air-LIH-kee-uh) cause ehrlichiosis. In the United States, the Lone Star tick, the blacklegged tick, and the western blacklegged tick spread the illness. People have long known that ehrlichiosis causes disease in animals, but the first case in humans in the United States was not identified until the 1980s. Ehrlichiosis is found in most parts of the country.

Symptoms of ehrlichiosis resemble those of the flu: fever, chills, extreme tiredness, headache, muscle and joint pain, nausea, and vomiting. There is usually no rash in adults, but many children develop a rash. Some people have no symptoms or only mild symptoms. Complications, although rare, can occur in the elderly and people with weakened immune systems.

Lyme disease

Lyme disease gets its name from the town in Connecticut where doctors discovered the disease in 1977. It is the most common tick-borne illness in the United States. The majority of cases appear in the northeastern, north central, and northwestern states.

Tips for Removing a Tick

Using tweezers, grasp the tick as close to the head as possible.

Pull firmly and steadily until the tick lets go (do not squeeze or twist).

Put the tick in a jar of alcohol in case it is needed for diagnosis.

Swab the bite area with alcohol.

Petroleum jelly and lit matches do not help in tick removal and should not be used.

* host is an organism that provides another organism (such as a parasite or virus) with a place to live and grow.

The bacterium Borrelia burgdorferi (buh-REEL-e-uh burg-DOR-feree), transmitted through deer ticks, causes Lyme disease. In most cases, the first sign of infection is the erythema migrans (air-uh-THEE-muh MY-granz) rash. It usually appears at the site of the tick bite, although it can develop anywhere on the body. The rash can be round, oval, or shaped like a bull's-eye with a red center surrounded by a clear area and then by a ring of red. Other early signs of the disease, such as extreme tiredness, headache, muscle aches, and fever, are similar to those of many infections, making diagnosis difficult. Not everyone who has Lyme disease develops the rash, and some people never show any symptoms.

The early disseminated * stage of the disease typically comes weeks to months later in people who have not received treatment. Symptoms at this stage include multiple rashes, meningitis * , radiculitis * , Bell's palsy * , and in some cases abnormalities of the heart rhythm. Lyme disease is not usually fatal, but if the illness remains untreated it can cause symptoms even years later. They can include arthritis, confusion, lack of coordination, difficulty in sleeping, and mood changes.


Babesiosis is a rare disease that appears mainly in the northeastern United States. It spreads through the bite of a deer tick that has been infected with a Babesia (buh-BE-she-uh) parasite, which attacks red blood cells. Because the deer tick also can spread Lyme disease, some people become infected with both diseases at the same time.

In healthy people, babesiosis infection may cause no symptoms. In others, early symptoms are extreme tiredness, lack of appetite, and a general feeling of being sick. Later symptoms include high fever, sweating, muscle aches, headache, and dark urine. The symptoms of babesiosis are similar to those of malaria * . Infected people also may have anemia * because of the parasite's attack on their red blood cells. The disease is not often fatal, but it can cause complications in the elderly, pregnant women, people with weakened immune systems, and people who have had their spleen removed.

How Common Are Tick-borne Infections?

About 16,000 cases of Lyme disease occur in the United States each year. RMSF is the second most common type of tick-borne illness, with the U.S. Centers for Disease Control and Prevention receiving as many as 1,200 reports of RMSF cases each year.

In contrast to these diseases, both ehrlichiosis and babesiosis are rare, with about 1,200 reports of ehrlichiosis over an 11-year period and several hundred cases of babesiosis since it was first reported in 1966.

How Are Tick-borne Infections Diagnosed
and Treated?

Diagnosing a tick-borne illness can be difficult because the symptoms of many of the illnesses resemble those of the flu or other infections. One of the best clues is a recent tick bite, but many people do not remember being bitten.

* disseminated describes a disease that has spread widely in the body.

* meningitis (meh-nin-JY-tis) is an inflammation of the meninges, the membranes that surround the brain and the spinal cord. Meningitis is most often caused by infection with a virus or a bacterium.

* radiculitis (ruh-dih-kyoo-LYE-tis) is numbness, tingling, or burning sensation along the course of a nerve due to irritation or inflammation of the nerve.

* Bell's palsy (PAWL-zee) is a condition in which there is weakness or loss of function of muscles on one side of the face.

* malaria (mah-LAIR-e-uh) is a disease spread to humans by the bite of an infected mosquito.

* anemia (uh-NEE-me-uh) is a blood condition in which there is a decreased amount of oxygen-carrying hemoglobin in the blood and, usually, fewer than normal numbers of red blood cells.

* antibodies (AN-tih-bah-deez) are protein molecules produced by the body's immune system to help fight specific infections caused by microorganisms, such as bacteria and viruses.

* biopsy (BI-op-see) is a test in which a small sample of skin or other body tissue is removed and examined for signs of disease.

Doctors often diagnose these diseases based on the patient's history of symptoms and activities, where the patient lives or became sick, and a physical examination that includes looking for rashes. A doctor may order a blood test to check for antibodies * to the organism causing the infection, but these tests usually are not helpful in the early stages of the illness. Skin biopsy * from a rash area may confirm a diagnosis.

Antibiotics are effective against the bacterial infections. Anti-parasitic medicines work well for babesiosis. In most cases, patients recover at home. Sometimes, however, especially in cases of RMSF, patients may need hospitalization for more intensive antibiotic therapy and supportive care.

What Should People Expect if They Have a
Tick-borne Infection?

In almost all cases of tick-borne illnesses, quick treatment brings a complete cure, although it may take several months before all symptoms disappear. Untreated cases of Lyme disease can cause problems years after the tick bite.

Complications, while rare, can occur. For example:

  • RMSF can cause paralysis * , hearing loss, and nerve damage.
  • Ehrlichiosis can cause kidney * failure, respiratory problems, seizures * , and coma * .
  • Long-term complications from Lyme disease include chronic * arthritis and nervous system problems.
  • Babesiosis can cause respiratory problems, seizures, kidney failure, and other organ failure.

Can People Prevent Tick-borne Infections?

Avoiding areas where ticks are found is the best way to prevent the diseases they carry. If people venture into areas where ticks are likely to live, experts suggest that they wear long pants and long-sleeved shirts in light colors (to make it easier to find ticks) when going outside and that they tuck their pant legs into their socks. Applying insect repellents also can be helpful. Checking for ticks after being outside is also wise. Studies show that ticks may not infect people until they have been attached for 2 days, so quickly removing ticks can help prevent illness. When ticks are found, they should be removed, and people should watch for signs of infection, such as rash or fever.

* paralysis (pah-RAH-luh-sis) is the loss or impairment of the ability to move some part of the body.

* kidney is one of the pair of organs that filter blood and remove waste products and excess water from the body in the form of urine.

* seizures (SEE-zhurs) are sudden bursts of disorganized electrical activity that interrupt the normal functioning of the brain, often leading to uncontrolled movements in the body and sometimes a temporary change in consciousness.

* coma (KO-ma) is an unconscious state in which a person cannot be awakened and cannot move, see, speak, or hear.

* chronic (KRAH-nik) means continuing for a long period of time.



American Lyme Disease Foundation, Inc., Mill Pond Offices, 293 Route 100, Somers, NY 10589. The American Lyme Disease Foundation provides information on Lyme disease and other tick-borne illnesses on its website.
Telephone 914-277-6970
http://www.aldf.com Lyme Disease Foundation, Inc., One Financial Plaza, Hartford, CT 06103. The Lyme Disease Foundation offers information on tick-borne illnesses and avoiding tick bites on its website.

Telephone 860-525-2000


KidsHealth.org . KidsHealth is a website created by the medical experts of the Nemours Foundation and is devoted to issues of children's health. It contains articles on a variety of health topics, including tick-borne infections.

See also
Lyme Disease
Rickettsial Infections
Rocky Mountain Spotted Fever

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