Babesia: Symptoms, Treatment, and Congenital Transmission
Can Babesia Be Passed From Mother to Baby?
Yes. Babesia can be transmitted during pregnancy, though it is rare. This case shows that one twin may be infected while the other is not.
Babesia is a tick-borne infection that primarily affects red blood cells and commonly causes anemia, along with fatigue and fever. Patients often search for Babesia symptoms, treatment, and how it is transmitted—including whether it can be passed from mother to baby during pregnancy.
How Is Babesia Transmitted?
Babesia is primarily transmitted through the bite of infected ticks. Less commonly, it can be spread through blood transfusions or from mother to baby during pregnancy (congenital transmission).
Congenital Babesia Transmission in Twins
When Vertical Transmission Affects Only One Twin
Congenital babesia is rare—but this case proves it happens. The patient was born at 36 5/7 weeks by C-section. At five-weeks-old the newborn presented to the emergency department with pallor, increased lethargy and difficulty feeding.
The newborn was “more difficult to arouse and very pale compared to her twin brother,” the mother reported.
This case of Babesia transmitted from mother to baby is the first report describing asymmetric transplacental transmission in twins—one twin infected, the other not.
The Mother’s History: Congenital Babesia Risk Factors
The mother had a febrile illness during pregnancy at approximately 23–24 weeks of gestation, associated with a maculopapular rash that resolved spontaneously, according to Walker et al.
She had made several trips to Cape Cod, Massachusetts—an area endemic for Lyme disease and tick-borne co-infections.
This timing is important. Infection during the second or third trimester creates an opportunity for transplacental transmission.
Babesia Symptoms in Newborns
At examination, the newborn was febrile, pale, and had tachycardia and tachypnea.
Blood work revealed anemia, thrombocytopenia, and elevated liver enzymes.
A blood smear showed intraerythrocytic parasites consistent with Babesia microti.
These findings reflect hemolytic anemia caused by destruction of red blood cells—a hallmark feature of Babesia infection.
Babesia Treatment in Newborns
The newborn was treated with a blood transfusion along with atovaquone and azithromycin.
Within 5 days, the Babesia infection cleared.
The twin brother tested negative, while the mother’s results showed prior infection consistent with exposure during pregnancy.
Why Only One Twin Was Infected
This case raises an important question: why would only one twin be infected?
Possible explanations include differences in placental blood flow, timing of maternal infection, and variability in immune response.
This demonstrates that maternal infection does not always result in fetal infection—even in twins.
What Is Congenital Transmission?
Congenital transmission refers to the passage of an infection from mother to baby during pregnancy.
In Babesia, this occurs when parasites cross the placenta and infect the fetus.
Is Babesia Transmitted During Pregnancy?
Yes. Although rare, Babesia can be transmitted during pregnancy, particularly when infection occurs in the second or third trimester.
Pregnant women with fever or tick exposure in endemic areas should be evaluated for Babesia and other tick-borne infections.
Related: Babesia and Lyme: What Patients Need to Know
Frequently Asked Questions
Can Babesia be passed from mother to baby?
Yes. Babesia can be transmitted during pregnancy, although it is rare. This typically occurs when parasites cross the placenta, particularly if infection develops during the second or third trimester.
What are the symptoms of Babesia in newborns?
Pallor, lethargy, poor feeding, fever, and anemia are common signs.
How is Babesia diagnosed?
A blood smear showing parasites in red blood cells confirms the diagnosis. Additional Babesia testing may be required in less obvious cases.
How is Babesia treated?
Treatment includes atovaquone and azithromycin, sometimes with blood transfusion.
This case adds to growing evidence that Babesia should be considered in newborns with unexplained anemia and maternal exposure risk.
Clinical Takeaway
This case highlights that Babesia can be transmitted during pregnancy—and may affect one twin but not the other.
Clinicians should consider Babesia in newborns with anemia and maternal exposure history, particularly in endemic regions.
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
How safe are blood transfusions now? (Babesia?)
Reeeeeally sad that this type of info is only coming out now, when my sons were born in 80’s & 90’s with the exact same problems! Funny how NO doctors other than infectious disease specialists would listen then. Now my grandchildren are going thru this too now. This is NOT…. new INFO…. I am 13th generation Cape Cod & tick illnesses have been here over 100 yrs… get a clue!! The gov’t & docs know.. but WE… don’t all die from these illnesses so.. no big deal right??