In addition to carrying Lyme disease, some ticks also carry a microparasite known as Babesia microti that can infect human blood.

These microscopic insects often live in deer ticks. The infection they cause is called babesiosis and can occur with or separately from Lyme disease. Babesiosis can be severe if not treated.

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Ticks may cause Lyme disease or babesiosis. Avoiding their haibtats is one way to avoid these conditions.

Babesia microti is a malaria-like parasite that lives in certain kinds of ticks.

The microscopic organisms can be transmitted to humans via a tick bite, from a mother to an unborn child, or through a tainted blood transfusion. The infection the parasite causes is known as babesiosis.

Babesiosis can result in a very mild illness, but it can be life-threatening for certain groups of people. At-risk groups include:

  • the elderly
  • people without a spleen
  • immunocompromised individuals, including those with cancer or AIDS
  • people with other serious conditions, including liver or kidney disease

Symptoms of babesiosis may mimic symptoms of Lyme disease, a condition that is also transmitted by ticks. The symptoms of babesiosis can range from barely noticeable to severe.

Some people may not even realize they have babesiosis, while others may experience more generalized signs of illness, including:

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Babesiosis may cause serious complications in those with weakened immune systems, the elderly, and those with chronic liver conditions.

In some cases, babesiosis may cause more serious illness as a result of the infection. These complications can include any combination of the following:

  • low blood pressure
  • kidney failure
  • severe hemolytic anemia from the excess destruction of red blood cells
  • liver problems

Babesiosis is caused by the parasite babesia. This parasite has a life cycle that involves two host organisms. Ticks, the first host, transmit babesia to humans via a bite. Humans are the second and end-stage host organism for babesia.

Except in the rare cases of infections spread from mother to fetus or via blood transfusion, humans can not transmit babesiosis from person to person.

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A diagnosis of babesiosis may be made by examining a blood sample under a microscope.

Because of the nonspecific nature of the early symptoms of babesiosis, diagnosis is often difficult in the initial stages of the disease.

Doctors working in an area where babesiosis infections are common may test for it in people experiencing some of the symptoms of babesiosis.

As part of the diagnosis, a doctor will likely examine a blood smear under a microscope to look for signs of the babesia parasite.

A doctor may also order blood work. Blood samples are sent to specialized labs that search for signs and indicators that suggest babesia parasites are present.

Additional blood work and testing may be ordered to help rule out other causes of the symptoms.

Babesia and Lyme disease are considered coinfections. Both are most commonly spread to humans through tick bites, and they share some similar symptoms.

However, babesia and Lyme disease are not dependent on each other to exist. A person may test positive for one, both, or neither.

Each condition caused by these infections requires different treatment. Therefore, treating one type of infection does not treat the other. In some people, babesia parasites may go undetected, which can lead to the parasites being spread through blood transfusions.

Fortunately, babesia and Lyme disease exist together in a very small percentage of cases. In the United States, babesia is found primarily in the Northeast.

A person infected with babesia may experience no symptoms or signs of babesiosis for years after a tick bite, or ever. Lyme disease is much more likely to cause signs and symptoms, so the person is much more likely to be treated.

Even if a person tests positive for babesiosis, if they do not have any symptoms of the infection, no treatment is necessary. However, in other cases, treatment with an antiparasitic drug, such as quinine or atovaquone, is needed to cure the infection.

In the most severe cases, antibacterial drugs, including clindamycin or azithromycin, may be used.

People with severe cases of babesiosis may require hospitalization for intravenous medications, fluids, blood transfusions, and treatment of any complications. These include liver problems and kidney failure.

Some people who contract babesiosis may never experience any symptoms, while others may experience a life-threatening illness. The overall likelihood of either scenario depends on the health of the individual, how soon babesiosis is diagnosed, and the person's response to treatment.

With early detection and treatment, most people can expect to make a full recovery. However, some people, particularly those with impaired immune function, may suffer from chronic relapses of babesiosis.

People who experience a reoccurrence of babesiosis symptoms will need to be monitored with repeat blood draws and continued medications.

Steps can be taken to prevent babesiosis and other tick-borne illnesses. Because ticks are most common in parts of the Midwest and Northeast U.S. during the warmer months, people living in these areas of the country should be most aware of tick bite prevention.

Following the steps described below may reduce tick exposure, lowering the risk for babesiosis and other diseases:

  • check for ticks on the skin every few hours when outdoors
  • use insect repellant before going outside
  • avoid areas of tall grass or brush
  • check pets for ticks when they come inside
  • consider spraying insecticides on the lawn
  • consider using a flea and tick medication to prevent pets from getting ticks
  • wear long pants tucked into socks and sleeves tucked into gloves when going into woods
  • create a mulch barrier between wooded areas and residential zones

Preventing and reducing exposure to ticks reduces the risk of infection with babeosis, as well as Lyme disease.