Can Babesia Pass From Mother to Baby During Pregnancy?
Babesia can rarely pass from mother to baby
Infants may appear healthy at birth
Symptoms can develop weeks later
Congenital babesiosis is a rare infection that occurs when Babesia is transmitted from a mother to her baby during pregnancy. Published cases show that maternal infection may be mild or unrecognized while the infant later develops anemia, thrombocytopenia, neutropenia, fever, or parasites in the red blood cells.
In this Inside Lyme case study, I discuss two mothers who transmitted Babesia microti to their babies. Saetre and colleagues described these cases in the Journal of the Pediatric Infectious Diseases Society.
Babesia is a parasite that infects red blood cells. It is most often transmitted through the bite of an infected blacklegged tick, but it can also be acquired through a blood transfusion or, rarely, transmitted from a pregnant mother to her baby.
The two mothers in this report were diagnosed with Lyme disease during the third trimester. Both were treated with amoxicillin for Lyme disease, but neither was treated for Babesia. Their infants later developed congenital babesiosis.
I discussed these cases from the infants’ perspective in an earlier Inside Lyme podcast. In this article, I focus primarily on the mothers, the evidence of maternal Babesia infection, and the clinical questions raised by these cases.
What is congenital babesiosis?
Congenital babesiosis refers to Babesia infection acquired from the mother before birth. The parasite may cross the maternal-fetal interface and infect the infant’s red blood cells.
Symptoms may not be present at birth. Reported infants have developed illness days or several weeks later, including:
- Anemia or severe hemolytic anemia
- Thrombocytopenia, or a low platelet count
- Neutropenia, or a low neutrophil count
- Fever or irritability
- Pallor
- Poor feeding
- Fatigue or decreased activity
- Parasites visible in red blood cells
Some affected infants have required blood transfusions in addition to antimicrobial treatment.
First mother with Babesia
The first mother lived in Westchester County, New York, an area endemic for Lyme disease and tick-borne coinfections. I live and practice medicine in the same county.
She was diagnosed with Lyme disease during her third trimester at 32 weeks of pregnancy after developing an erythema migrans rash. She was treated with amoxicillin.
Amoxicillin is commonly prescribed for Lyme disease during pregnancy. However, amoxicillin does not treat Babesia because Babesia is a parasite rather than a bacterium.
Two weeks after her Lyme disease diagnosis, the mother tested positive for Babesia microti IgM antibodies. This result was consistent with possible recent Babesia infection, although antibody results must be interpreted together with the patient’s clinical history and other laboratory findings.
The mother was not treated for Babesia. She and her baby boy went home after delivery.
Her baby developed congenital babesiosis
The baby boy was diagnosed with Babesia approximately 4½ weeks after birth. This delay is important because congenital babesiosis may not be apparent during the newborn period.
When the infant was diagnosed, the mother was again tested for Babesia. Her testing was now positive for Babesia IgG antibodies. The change from an IgM response to an IgG response provided additional evidence that she had acquired Babesia during pregnancy.
The infant was treated for Babesia and recovered. The mother was not treated for Babesia.
This case illustrates how a mother may have limited or unrecognized symptoms while her infant later develops clinically apparent infection.
Second mother with Babesia
The second mother lived in Putnam County, New York, another region where Lyme disease and Babesia are endemic. Putnam County is located immediately north of Westchester County.
She developed muscle soreness and fever that lasted approximately two weeks. At 37 weeks of pregnancy, she was diagnosed with Lyme disease after developing an erythema migrans rash.
She was treated with amoxicillin. Initial laboratory testing for other tick-borne infections was not positive at the time of her Lyme disease diagnosis.
Negative testing at a single point in time does not always exclude Babesia. Parasite levels may be low, antibody production may not yet be detectable, or the testing method may not identify an early infection.
Her baby tested positive after delivery
After delivery, the baby girl’s blood tested positive for Babesia microti by polymerase chain reaction, or PCR. At that time, the infant was considered asymptomatic and was not treated.
The physicians did not initially identify Babesia parasites on a blood smear. The mother and baby were discharged home.
When the baby was 18 days old, Babesia parasites were identified in her red blood cells. She was hospitalized and treated with antimicrobial and antiparasitic medications. She also required a blood transfusion.
The mother’s subsequent testing was positive for Babesia by PCR, IgM, and IgG. These findings supported maternal infection during the third trimester and vertical transmission to the infant.
The baby was treated for congenital babesiosis. The mother was not treated for Babesia.
Congenital babesiosis may have a delayed presentation
These cases demonstrate that an infant with congenital babesiosis may appear well immediately after birth. Symptoms and abnormal blood counts may emerge days or weeks later as the parasite multiplies within red blood cells.
A separate report described a well-appearing infant who developed thrombocytopenia and parasitemia greater than 4%. The diagnosis was established through the maternal history and examination of blood smears from the mother and infant. The child recovered following oral treatment.
Other published infants have presented at four to five weeks of age with fever, pallor, irritability, poor feeding, pancytopenia, severe anemia, neutropenia, thrombocytopenia, and parasitemia. Placental tissue has also tested positive for Babesia microti DNA in reported cases.
How is congenital babesiosis diagnosed?
Diagnosis may require more than one testing method. Evaluation can include:
- A complete blood count to identify anemia, thrombocytopenia, or neutropenia
- A peripheral blood smear to look for parasites inside red blood cells
- PCR testing for Babesia DNA
- Babesia IgM and IgG antibody testing
- Evaluation of the mother for evidence of current or recent Babesia infection
- Testing of placental tissue when clinically appropriate and available
A negative initial smear or antibody test may not exclude early or low-level infection. Repeat testing may be appropriate when the maternal exposure history, symptoms, or infant’s blood-count abnormalities continue to suggest Babesia.
Can Lyme disease and Babesia occur together during pregnancy?
Yes. The same blacklegged ticks that transmit Lyme disease may also transmit Babesia microti. A pregnant patient diagnosed with Lyme disease may therefore have been exposed to more than one tick-borne pathogen.
In these two cases, the mothers were diagnosed and treated for Lyme disease, but Babesia infection was either detected later or not recognized initially. Treatment directed at Lyme disease does not necessarily treat Babesia.
Amoxicillin and doxycycline do not treat Babesia. Management of babesiosis during pregnancy is challenging because commonly used Babesia therapies have limited pregnancy safety data, and treatment decisions should be individualized. As a result, treating Lyme disease during pregnancy does not necessarily address an unrecognized Babesia coinfection.
What can we learn from these cases?
- Women can acquire Babesia during pregnancy.
- Babesia can rarely be transmitted from a pregnant mother to her baby.
- A mother may have mild, nonspecific, or unrecognized Babesia infection.
- An infant with congenital babesiosis may initially appear healthy.
- Symptoms may not develop until several weeks after birth.
- Anemia, thrombocytopenia, and neutropenia can be important diagnostic clues.
- A negative initial test does not always exclude early Babesia infection.
- Lyme disease treatment does not necessarily treat a Babesia coinfection.
What questions remain unanswered?
Congenital babesiosis has been reported infrequently, and the available literature consists largely of individual cases and small case series. Important questions remain:
- How often do pregnant women acquire Babesia from a tick bite?
- How often is maternal Babesia infection asymptomatic or overlooked?
- Which pregnant patients with Lyme disease should also be evaluated for Babesia?
- Which tests are most reliable during pregnancy and immediately after birth?
- How long should infants with possible exposure be followed?
- What treatment approach is safest and most effective during pregnancy?
- Should pregnant women with laboratory evidence of Babesia but few symptoms be treated?
- What are the long-term outcomes for untreated mothers with evidence of Babesia infection?
These questions cannot be answered from two cases alone. Additional prospective studies are needed to determine the frequency of vertical transmission and the optimal approach to maternal testing, infant monitoring, and treatment.
Frequently Asked Questions
What is congenital babesiosis?
Congenital babesiosis is a rare infection that occurs when Babesia is transmitted from a pregnant mother to her baby before birth.
Can Babesia pass through the placenta?
Published case reports provide evidence that vertical transmission of Babesia microti can occur during pregnancy. Babesia DNA has also been detected in placental tissue in reported cases.
When do symptoms of congenital babesiosis appear?
Symptoms may appear shortly after birth or several weeks later. Reported findings include fever, poor feeding, pallor, anemia, thrombocytopenia, neutropenia, and parasitemia.
Can a baby with congenital babesiosis initially appear healthy?
Yes. Several reported infants initially appeared well but later developed abnormal blood counts, parasitemia, or symptoms of hemolytic anemia.
How is congenital babesiosis diagnosed?
Diagnosis may involve a complete blood count, peripheral blood smear, Babesia PCR, antibody testing, and evaluation of the mother for evidence of recent or current infection.
Can congenital babesiosis be treated?
Yes. Reported infants have recovered after treatment, commonly with atovaquone and azithromycin. Infants with severe anemia may also require blood transfusions or other supportive care.
Does amoxicillin treat Babesia during pregnancy?
No. Amoxicillin may be used to treat Lyme disease during pregnancy, but it does not treat Babesia. Babesiosis requires a treatment regimen directed specifically at the parasite.
Should a pregnant woman with Lyme disease be evaluated for Babesia?
Evaluation may be appropriate when exposure occurred in a Babesia-endemic area or when symptoms such as fever, sweats, anemia, low platelets, or persistent illness raise concern for coinfection. Decisions about testing and treatment should be individualized with the patient’s obstetric and medical clinicians.
Clinical Takeaway
Congenital babesiosis is rare, but published reports demonstrate that Babesia microti can be transmitted from mother to infant during pregnancy.
The mother may have few symptoms, and the infant may initially appear well. Anemia, thrombocytopenia, neutropenia, fever, pallor, poor feeding, or delayed parasitemia should raise concern, particularly when the mother lived in or traveled to a Babesia-endemic area.
Most pregnant patients with Lyme disease do not have babesiosis. However, clinicians should remain alert to the possibility of coinfection when the history, symptoms, laboratory findings, or epidemiologic exposure support further evaluation.
Early recognition and continued follow-up may allow congenital babesiosis to be diagnosed and treated before severe hematologic complications develop.
Related Articles
These articles provide additional information about Babesia in infants, severe infection, testing, and other clinical presentations.
Blood donor infects premature infants with Babesia
The case of an untreated Babesia infection
Wide range of Babesia symptoms and presentations
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. Journal of the Pediatric Infectious Diseases Society. 2018;7(1):e1–e5.
- Iyer S, Goodman K. Congenital babesiosis from maternal exposure: a case report. Journal of Emergency Medicine. 2019;56(4):e39–e41.
- Hachey K, Lewis D, Rodriguez JL, Richardson MW, Johnston AM. Two cases of congenital babesiosis. Open Forum Infectious Diseases. 2019;6(Suppl 2):S899–S900.
- Aderinboye O, Syed SS. Congenital babesiosis in a four-week-old female infant. Pediatric Infectious Disease Journal. 2010;29(2):188.
- Joseph JT, Purtill K, Wong SJ, et al. Vertical transmission of Babesia microti, United States. Emerging Infectious Diseases. 2012;18(8):1318–1321.
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
I’m extremely interested in this topic. I have tested positive for Babesiosis. I have elevated HLA and C-Reactive Protein levels that fluctuate off the charts. I now have a child with Babesia and is suffering. He is now being treated, I was not. Furthermore, I suspect my other two children also have it as well. We are awaiting test results. What I’m trying to find out, is this:
1. Could my Babesia have been spread to ALL my children? Why are we not screening for this?
2. How likely is it congenital versus environmental?
3. What are long term effects of untreated Babesia?
My family lives in South Jersey. We took my 4 week old daughter to the hospital for a fever of 100.9. They did a spinal tap and various blood tests and found that she had Babesia. Doctors believe that I was bitten by a tick during pregnancy. Doctors at that hospital had never seen Babesia in a newborn before, but they knew exactly how to treat it. They gave her antibiotics and she ended up needing two blood transfusions to treat her anemia. We spent a week in the hospital. When we left her parasite levels were below 1% and her hemoglobin was at a 9.5. Very terrifying experience for a new mother and father to go through, but she is the perfect little baby now at two months old.