What You Should Know About Babesia

Another disease to thank ticks for


Ticks can be an awful problem when the temperatures get warm. They can spread a lot more than just Lyme disease.

What is Babesiosis?

It is caused by a microscopic Babesia parasite that infects our red blood cells after a tick bite. It can explode red blood cells much like Malaria. Babesia rates have been climbing and may reach become as prevalent as Lyme disease.

What is the disease like?

It may cause no symptoms or very mild symptoms.

It can also cause fever, chills, body sweats, headache, body aches, loss of appetite, nausea, lightheadedness and/or fatigue.

The parasite enters directly into red blood cells, which can cause these cells to pop or lyse. This can cause a hemolytic anemia (meaning the red blood cells have been destroyed). This blood loss can cause fatigue or more serious symptoms.

How is it transmitted?

  • Tick bite (Babesia microtia is transmitted in nature by Ixodes scapularis ticks)
  • Blood Transfusion 
  • Mother-to-child during pregnancy or at birth

Can I get it through a blood transfusion?

Although rare, yes. It's actually the most commonly transmitted infection through transfusion in the US. Blood is not currently screened for Babesia. It is often mild - and so someone might still donate blood. Fortunately, most cases in blood transfusion recipients do well. Still, 18 confirmed or probable cases were identified from 2005-7 and 5 of these died.

Those who have a transfusion may have blood from out of state - or from a healthy donor who traveled out of state. Infections may not be picked up quickly in areas where Babesia is not usually found.

Where is it found?

The disease is largely found in the Northeast. Some of the highest risk areas are in Nantucket and Martha's Vineyard, Massachusetts as well as other areas along or off the coast, including Block Island, Rhode Island as well as Shelter Island, Fire Island, and eastern Long Island, New York.

It is also found in New Jersey, Connecticut, and other parts of New England. In addition, it has been found in the upper Midwest - Wisconsin, and Minnesota.

Another type, Babesia divergens, is seen in Europe, where it is rare. There it has been found largely, though not always, in those who are immunocompromised or have no spleen, in whom it causes very severe disease.

The disease is often not identified - especially mild illnesses - and is underreported.

How does it spread?

It spreads through tick bites from, Ixodes scapularis in the US (and less commonly Ixodes ricinus in Europe). The infection usually comes from the young nymph stage, when the tick is 'questing' or searching for a blood meal during spring and summer. The nymph state is very small so many will not remember seeing a tick or a tick bite.

Who is most at risk?

Those with

  • no spleens
  • a weak immune system (from HIV, cancer treatment, lymphoma)
  • other serious medical conditions (such as kidney disease)
  • low blood counts or platelet counts
  • or who are elderly

When do symptoms start?

1 week after exposure, but it can vary.

What is treatment like?

There are treatments (which actually include medications used to treat malaria, another parasite in red blood cells).

Usually, treatment, if given, is an oral medication.

A very small number (such as those with no spleens) become very ill and require intensive care treatment, including IV treatment, and very rarely assistance breathing (for ARDS, Acute Respiratory Distress Syndrome) and even exchange transfusions and dialysis. This is very rare.

Others do not require treatment. About 1 in 4 have little or no symptoms. The disease can resolve without treatment.

A doctor can discuss with the CDC if there is a question about whether someone needs treatment.

How is Babesia diagnosed?

A laboratory technician will usually need to look at the blood on a slide to identify it.

This is much like how malaria is usually identified. Babes creates a specific image on the blood slide - especially a "Maltese cross formation" - that someone who is experienced will see. The percentage of red blood cells infected (i.e. 1%) will help determine how severe the disease is.

Some automated blood tests can also identify that a parasite is present. There are antibodies to confirm the diagnosis.

Can I get more than one tick-borne infection?

Yes. It's important to be tested for other infections - such as Lyme disease (Borrelia burgdorferi) Anaplasmosis (Anaplasma phagocytehilum). The Blacklegged tick (Ixodes scapularis) spreads these 3 diseases. Many with Lyme disease have other co-infections, including Babesia. Ticks are known to carry more than one infection.

How do I avoid ticks?

Avoid areas with high grasses, bushes, and wooded areas, especially in warmer months (spring through summer into autumn)

When in these potential tick areas:

  • Use insect repellent with DEET
  • Wear clothing with long sleeves and pants; pull socks over pant legs
  • Use permethrin on clothing

Immediately after visiting tick areas:

  • Do a full-body tick check – especially through bathing/showering
  • Check pets and any gear for ticks

Carefully remove ticks. If a tick is not on for 36-48 hours, it is not expected to transmit Babesia. For advice on removing ticks, please check out this CDC page.

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