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Babesiosis

• Babesiosis [bab-EE-see-OH-sis] is a rare parasitic disease that is transmitted to people by infected ticks.
• Babesiosis occurs mainly in coastal areas in the northeastern United States, especially the offshore islands of New York and Massachusetts.
• Elderly persons and people with weakened immune systems can get severe complications from babesiosis.
• No vaccine against babesiosis is available. To prevent babesiosis, avoid exposure to ticks, and remove attached ticks right away.

What is babesiosis?

Babesiosis in humans is a rare, potentially fatal disease that is transmitted by the bite of an infected tick. Babesiosis is a common infection in animals.

What is the infectious agent that causes babesiosis?

Babesiosis is caused by the Babesia parasite.

Where is babesiosis found?

Babesiosis occurs mainly in coastal areas in the northeastern United States, especially the offshore islands of New York and Massachusetts. Cases have also been reported in Wisconsin, California, Georgia, and in some European countries.

How do people get babesiosis?

Babesiosis is most commonly spread to people by the bite of a tick infected with the Babesia parasite. Babesiosis is spread by deer ticks, which are carried mainly by deer, meadow voles, and mice. Deer ticks also spread Lyme disease. People can be infected with both babesiosis and Lyme disease at the same time. People can also get babesiosis from a contaminated blood transfusion.

What are the signs and symptoms of babesiosis?

The parasite attacks the red blood cells. Symptoms, if any, begin with tiredness, loss of appetite, and a general ill feeling. As the infection progresses, these symptoms are followed by fever, drenching sweats, muscle aches, and headache. The symptoms can last from several days to several months.

How soon after exposure do symptoms appear?

It can take from 1 to 12 months for the first symptoms to appear, but less time for persons with weakened immune systems.

How is babesiosis diagnosed?

Laboratory diagnosis is based on identifying the parasite in red blood cells.

Who is at risk for babesiosis?

Anyone can get babesiosis, but some people are at increased risk for severe disease:

• Elderly persons
• Persons with weakened immune systems
• Persons whose spleens have been removed

What complications can result from babesiosis?

Complications include very low blood pressure, liver problems, severe hemolytic anemia (a breakdown of red blood cells), and kidney failure. Complications and death are most common in persons whose spleens have been removed. Other people usually have a milder illness and often get better on their own.

What is the treatment for babesiosis?

A combination of anti-parasite medicines can be effective in treating babesiosis.

How common is babesiosis?

It is not known how common babesiosis is in the United States. Most people have no symptoms, and those who do are usually older persons and people who are already sick with other conditions. Most cases occur during spring, summer, and fall.

Is babesiosis an emerging infectious disease?

Yes. The first case was reported from Nantucket Island, Massachusetts, in 1969. Since then, babesiosis has emerged as a health threat in the United States, with increasing reports of babesiosis symptoms and some deaths in areas where the risk of infection was not previously recognized.

How can babesiosis be prevented?

• No vaccine is available to protect humans against babesiosis. You can reduce your risk by taking these precautions against tick bites:
• During outside activities, wear long sleeves and long pants tucked into socks. Wear a hat, and tie hair back.
• Use insecticides to repel or kill ticks. Repellents containing the compound DEET can be used on exposed skin except for the face, but they do not kill ticks and are not 100% effective in preventing tick bites. Products containing permethrin kill ticks, but they cannot be used on the skin -- only on clothing. When using any of these chemicals, follow label directions carefully. Be especially cautious when using them on children.
• After outdoor activities, check yourself for ticks, and have a "buddy" check you, too. Check body areas where ticks are commonly found: behind the knees, between the fingers and toes, under the arms, in and behind the ears, and on the neck, hairline, and top of the head. Check places where clothing presses on the skin.
• Remove attached ticks immediately. Removing a tick before it has been attached for more than 24 hours greatly reduces the risk of infection. Use tweezers, and grab as closely to the skin as possible. Do not try to remove ticks by squeezing them, coating them with petroleum jelly, or burning them with a match.

This fact sheet is for information only and is not meant to be used for self-diagnosis or as a substitute for consultation with a health-care provider. If you have any questions about the disease described above, consult a health-care provider.

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