Can Babesiosis Be Passed From Mother to Baby? Two Newborn Cases
Congenital babesiosis has been reported in newborns
Two infants developed Babesia microti infection after maternal Lyme disease
Mother-to-child transmission appears possible
Can babesiosis be passed from mother to baby during pregnancy? Although uncommon, congenital babesiosis has been documented in newborns, including the two cases described here.
Congenital transmission had previously been described in seven cases in which infants developed fever, anemia, and thrombocytopenia. According to Saetre and colleagues, all seven infants required blood transfusions.
These were the first reported cases, to the authors’ knowledge, in which the mothers were diagnosed with Lyme disease before delivery and were subsequently found to have evidence of subclinical Babesia microti infection.
These reports concern congenital Babesia transmission. They do not establish that Lyme disease itself was transmitted to either infant.
“We describe the cases of 2 infants with congenital babesiosis born to mothers with prepartum Lyme disease and subclinical Babesia microti infection,” wrote Saetre and colleagues.¹
What Is Congenital Babesiosis?
Congenital babesiosis occurs when Babesia parasites are transmitted from an infected mother to her infant during pregnancy or delivery.
Reported symptoms and findings in newborns include:
- Fever
- Anemia
- Thrombocytopenia
- Neutropenia
- Pallor
- Irritability
- Poor feeding
- Splenomegaly
Both infants in this report were born to mothers diagnosed with Lyme disease during pregnancy who were subsequently found to have evidence of Babesia microti infection.
Two Newborns With Congenital Babesiosis
Infant #1
The first infant, a 4½-week-old boy, presented with a fever of 101.7°F, sleepiness, and periodic irritability.
His mother had been diagnosed with Lyme disease during the third trimester at 32 weeks’ gestation after developing an erythema migrans rash. She was treated successfully with amoxicillin.
A blood smear from the infant revealed 2% parasitemia consistent with Babesia infection.
He was treated with atovaquone and azithromycin. According to the authors, these medications were selected because they are generally better tolerated than clindamycin and quinine.¹
The infant did not require a blood transfusion. He also tested negative for antibodies to Borrelia burgdorferi, the bacterium that causes Lyme disease.
At his two-month follow-up visit, he was clinically well and his splenomegaly had resolved.
Infant #2
The second mother developed fevers and muscle aches at 35 weeks’ gestation. An erythema migrans rash appeared at 37 weeks, and she was treated with amoxicillin.
Her infant was born at 38 weeks without perinatal complications.
The 18-day-old girl was initially asymptomatic despite having a positive B. microti PCR test.
One week later, however, she developed neutropenia and anemia. She was hospitalized and treated with azithromycin and atovaquone.
Because of symptomatic anemia accompanied by malaise, tachycardia, and pallor, she required a blood transfusion on the second day of hospitalization.
Clindamycin was added on hospital day four because her parasitemia remained elevated and her hematocrit continued to fall.
The infant ultimately received all three antimicrobial medications for 14 days and recovered.
How Did Babesiosis Present in These Newborns?
The clinical presentations of these two infants resembled previously reported cases of congenital babesiosis.
Important findings included:
- Symptoms developing several weeks after birth
- Low-level parasitemia
- Fever
- Hemolytic anemia
- Thrombocytopenia
- Neutropenia
- A need for blood transfusion support in one infant
“Each infant developed symptoms between 19 and 41 days of age and, at the time of presentation to medical attention, had fever, pallor, hemolytic anemia, and thrombocytopenia,” explained Saetre and colleagues.¹
The delayed appearance of illness is clinically important. An infant with congenital babesiosis may appear healthy at birth and develop symptoms several weeks later.
Babesia and Lyme Disease Coinfection During Pregnancy
Lyme disease and babesiosis can be transmitted by the same blacklegged tick. A pregnant patient exposed to Lyme disease in an endemic region may therefore also have been exposed to Babesia microti.
The mothers in these cases had evidence of Babesia infection despite having mild or unrecognized Babesia-related symptoms. Treatment with amoxicillin addressed their Lyme disease but would not be expected to treat Babesia because Babesia is a parasite rather than a bacterium.
Babesia is one of several tick-borne coinfections that may accompany Lyme disease.
Questions Raised by These Cases
These two cases raise important clinical and research questions about Babesia infection during pregnancy and the risk of congenital transmission:
- Could Babesia infection during the first or second trimester contribute to pregnancy complications or fetal loss?
- Would clinicians recognize Babesia infection in a pregnant woman or newborn if the mother did not have an erythema migrans rash?
- Would the second infant have avoided complications if treatment had begun immediately after the positive PCR result?
- When should a pregnant woman diagnosed with Lyme disease also be evaluated for Babesia coinfection?
- How long should an infant with possible congenital exposure be monitored?
Two cases cannot determine how frequently congenital transmission occurs or establish a universal approach to screening and treatment. Additional studies are needed to determine the optimal management of pregnant women with possible Babesia infection and their infants.
Frequently Asked Questions
Can babesiosis be passed from mother to baby?
Yes. Although uncommon, published case reports have documented congenital babesiosis in newborns born to mothers infected with Babesia microti during pregnancy. The Centers for Disease Control and Prevention also recognizes pregnancy and delivery as rare routes of transmission.
Can a pregnant woman with Lyme disease also have Babesia?
Yes. Lyme disease and babesiosis can be transmitted by the same blacklegged tick, making coinfection possible in endemic regions.
Does Lyme disease treatment also treat Babesia?
Not necessarily. Amoxicillin may be used to treat Lyme disease during pregnancy, but it does not treat Babesia. Babesiosis requires treatment directed specifically at the parasite.
Can an infant with congenital babesiosis initially appear healthy?
Yes. An infant may appear healthy at birth and develop symptoms or abnormal blood counts days or several weeks later.
What symptoms can congenital babesiosis cause?
Reported symptoms and findings include fever, anemia, thrombocytopenia, neutropenia, pallor, poor feeding, irritability, and an enlarged spleen.
Can congenital babesiosis require a blood transfusion?
Yes. Several published cases have required transfusion support because Babesia can destroy red blood cells and cause severe anemia.
Clinical Takeaway
These two newborn cases add to the medical literature documenting congenital babesiosis.
Both infants were born to mothers diagnosed with Lyme disease during pregnancy who were subsequently found to have evidence of Babesia microti infection. The infants developed anemia, neutropenia, and thrombocytopenia, and one required a blood transfusion. Both recovered with treatment.
Although congenital babesiosis appears to be rare, published cases demonstrate that transmission from an infected mother to her infant can occur. The diagnosis should be considered when a newborn or young infant develops fever, anemia, thrombocytopenia, neutropenia, pallor, poor feeding, or splenomegaly—particularly when the mother lived in or traveled to a Babesia-endemic region.
These cases highlight the importance of recognizing possible Babesia coinfection during pregnancy and monitoring potentially exposed infants even when they appear healthy at birth.
This article is for informational purposes and is not a substitute for individual medical advice, diagnosis, or treatment.
Related Articles
- Tick-Borne Coinfections
- Babesia: Symptoms, Diagnosis, and Treatment
- Pediatric Lyme Disease
- Pregnancy and Lyme Disease
References
- Saetre K, Godhwani N, Maria M, Patel D, Wang G, Li KI, Wormser GP, Nolan SM. Congenital babesiosis after maternal infection with Borrelia burgdorferi and Babesia microti. J Pediatric Infect Dis Soc. 2018;7(1):e1–e5.
- Centers for Disease Control and Prevention. How babesiosis spreads. Updated February 12, 2024.
Dr. Daniel Cameron, MD, MPH
Lyme disease clinician with over 30 years of experience and past president of ILADS.
Symptoms • Testing • Coinfections • Recovery • Pediatric • Prevention
