It’s possible to develop anemia when you have Lyme disease due to a co-occurring parasitic infection passed on by the same tick bite.

Lyme disease (Lyme borreliosis) is a type of bacterial infection that you can get from a deer tick bite that transmits the Borrelia burgdorferi bacterium.

The initial symptoms of a Lyme disease infection usually improve after treatment with antibiotics, although it is possible to develop post-treatment Lyme disease syndrome.

If Lyme disease is left untreated or undertreated, serious complications may develop. Examples include brain inflammation, as well as problems with your heart, joints, and nerves.

Some people with Lyme disease also develop anemia, a common condition caused by low levels of red blood cells. This is most likely a result of a Babesia coinfection, transmitted by the same tick that gave you Lyme disease.

This article examines how coinfections of Lyme disease cause anemia, along with symptoms to be aware of, diagnosis, and treatment.

In some cases, a deer tick may transmit more than one pathogen when it bites. In addition to transmitting the bacterium that causes Lyme disease, a deer tick can transmit a parasite called Babesia microti.

The Babesia microti parasites specifically target red blood cells and can lead to a coinfection called babesiosis.

Babesiosis may be more challenging to detect at first because its symptoms are similar to those of Lyme disease.

Symptoms of Lyme disease can develop from 3 to 30 days after the initial tick bite and can feel like the flu. An erythema migrans (“bulls-eye”) rash can also develop and last for up to 3 weeks if the infection is left untreated.

At first, babesiosis may not necessarily cause any symptoms. When babesiosis does cause symptoms, it can take at least a week or longer to notice them.

You are most likely to experience flu-like symptoms, similar to Lyme disease, which can include:

  • a high fever
  • fatigue
  • chills
  • body aches
  • nausea
  • loss of appetite
  • lightheadedness
  • overall body weakness

What distinguishes Lyme disease from babesiosis is the development of anemic symptoms.

If babesiosis is left undiagnosed and untreated, the underlying parasites can cause hemolytic anemia. This type of anemia is characterized by the destruction of healthy red blood cells, which occurs faster than your bone marrow can make new ones to replace them.

Symptoms and signs of hemolytic anemia may include:

  • extreme fatigue
  • weakness
  • dizziness
  • splenic and/or liver enlargement

If you’re not feeling better despite taking prescribed antibiotics for Lyme disease, you should consider talking with a doctor about next steps.

This is especially the case if you also have possible symptoms of hemolytic anemia, or if you have risk factors for serious complications, such as:

If you have Lyme disease along with possible hemolytic anemia, a doctor may test you for babesiosis. This is done via a blood sample that is examined under a microscope. A lab technician can detect signs of parasites in your red blood cells.

Additionally, a doctor may run a complete blood count (CBC) test to determine the number of red blood cells in your body.

Not all cases of babesiosis coinfections require treatment, especially if you don’t have any symptoms. Medications, such as atovaquone with azithromycin or clindamycin with quinine, may be used to treat babesiosis infections.

However, severe hemolytic anemia does need treatment to help prevent complications, such as an enlarged heart or heart failure.

Possible options include:

Aside from hemolytic anemia, babesiosis can cause other serious complications, such as liver disease and dangerously low blood pressure.

While some people with Lyme disease might experience anemia, this is usually related to a common tick-borne coinfection called babesiosis.

Rather than being attributed to nutrient deficiencies, anemia from babesiosis is caused by red blood cell destruction from parasites.

If you have any possible symptoms of hemolytic anemia during Lyme disease treatment, see a doctor to determine whether you might also have a coinfection like babesiosis.