Babesia Infection in a 6-Week-Old Infant: Tick-Borne Case Study

Babesia infection in infants is rare—but this case shows that even very young babies can develop tick-borne disease. In this Inside Lyme case study, I discuss a 6-week-old infant diagnosed with Babesia in Long Island, New York, an area where Lyme disease and other tick-borne infections are common.

This case was described in the journal Pediatrics by Handel and colleagues in 2019.

How the Infant Became Infected With Babesia

The baby was evaluated in an emergency department in Long Island, New York—an area endemic for Lyme disease and other tick-borne infections.

The infant spent minimal time outdoors, according to the authors. However, there was tall grass in the yard, and the father worked painting home exteriors, which may have increased the likelihood of tick exposure.

The parents did not recall seeing a tick. Instead, they removed what they believed to be a bloody “flea” from the infant’s arm approximately 20 days before hospitalization. This illustrates how difficult it can be to recognize small ticks.

Babesia is a parasitic infection transmitted by the same ticks that carry Lyme disease. Because of this shared vector, physicians often evaluate patients with Babesia for tick-borne coinfections.

Babesia can also be transmitted through the blood supply or during pregnancy.

Diagnosis of Babesia in the Infant

The infant developed fever, irritability, vomiting, and poor feeding.

Initial laboratory testing revealed anemia and a low platelet count, but doctors were initially unable to determine the cause of the illness. Physicians began treatment with broad-spectrum antibiotics—ampicillin, ceftriaxone, and vancomycin—while searching for an explanation.

The baby was transferred to a second hospital where repeat laboratory tests again showed anemia, thrombocytopenia, abnormal liver function tests, and an enlarged spleen.

Finally, a laboratory test revealed the parasite Babesia inside red blood cells under the microscope. Approximately 3.6% of the infant’s red blood cells were infected.

Symptoms of Babesia Infection in Infants

Babesia infection can be difficult to recognize in infants because the symptoms are often nonspecific.

In this case, the baby developed fever, irritability, vomiting, and poor feeding. Laboratory testing revealed anemia and a low platelet count.

Babesia infects red blood cells and can lead to destruction of those cells, which may result in severe anemia. Infants with Babesia may also develop enlargement of the spleen and abnormal liver function tests.

Treatment of the Babesia Infant

The infant was treated with oral atovaquone and intravenous azithromycin, medications marketed in the United States as Mepron and Zithromax.

The infant’s anemia worsened during treatment. His hemoglobin dropped to 6.9 g/dL, which required a blood transfusion.

Because Babesia and Lyme disease can occur together, doctors also prescribed 14 days of amoxicillin for possible Lyme disease co-infection. You can read more about Babesia treatment.

Fortunately, the infant remained well on follow-up.

What This Babesia Infant Case Teaches Us

Babies can develop tick-borne infections even with minimal outdoor exposure.
Parents may not recognize ticks because they can be extremely small.
Diagnosis may be delayed because symptoms are nonspecific.
Doctors may treat for co-infections such as Lyme disease even without laboratory confirmation.

Questions Raised by This Case

Would earlier recognition of the tick bite have helped doctors diagnose Babesia sooner?
Would the infection have been recognized if parasites had not been seen under the microscope?
What if the infant had also been infected with Ehrlichia or Anaplasmosis?
What is the safest and most effective treatment duration for Babesia in infants?
How do clinicians determine recovery in infants who cannot communicate symptoms?

Editor’s Note

More physicians are needed with experience diagnosing and treating Babesia in children. Reliable laboratory tests to confirm infection and determine when Babesia has resolved would improve care.

Cases like this highlight the importance of recognizing tick-borne infections even in very young children living in endemic areas.

Parents concerned about tick-borne illness in children should also read about Babesia and Bartonella in children and other pediatric Lyme disease complications.

Frequently Asked Questions

Can infants get Babesia from a tick bite?

Yes. This case demonstrates that even a 6-week-old baby can develop Babesia after a tick bite.

What symptoms can Babesia cause in infants?

Symptoms may include fever, irritability, vomiting, poor feeding, anemia, and low platelet counts.

How is Babesia diagnosed?

Diagnosis is often made when parasites are seen inside red blood cells on a blood smear.

How can parents protect infants from ticks?

Check babies carefully after outdoor exposure, use protective netting on carriers, and inspect clothing, pets, and household members who may bring ticks indoors.