Probable Congenital Babesiosis in Infant, New Jersey, USA

Sonia Sethi; David Alcid; Hemant Kesarwala; Robert W. Tolan, Jr.


Emerging Infectious Diseases. 2009;15(5) 

In This Article


Of 10 cases of babesiosis in neonates that have been reviewed,[5] 2 were congenital,[3,4] 2 were transmitted by a tick bite,[6] and 6 were associated with transfusions.[5,7–9] The 2 congenital cases[3,4] are compared to our probable congenital case (Table 2). All 10 of the affected neonates were reported to have <9% parasitemia.[5] The illness ranged from no symptoms in 2 infants transfused with contaminated blood[8] to symptomatic disease (as in our infant) with fever and hepatosplenomegaly in 5 of 7 (71%), hemolytic anemia in 8 of 10 (80%), indirect hyperbilirubinemia in 4 of 5 (80%), and thrombocytopenia in 7 of 9 (78%).[5] Five of 8 (63%) patients required erythrocyte transfusion.[5] The infant we describe had all of these manifestations as well as a higher parasite count than described previously.[5] Clearly, the spectrum of neonatal babesiosis is variable and must be more fully elucidated, as must determinants of the illness's clinical course and parasite clearance. In neonates, the degree of parasitemia may not parallel the severity of the babesiosis.

The combination of quinine sulfate and clindamycin hydrochloride for treatment of a newborn with transfusion-associated babesiosis was described in 1982 and subsequently became the first accepted treatment.[7] A combination of azithromycin with atovaquone for 7 to 10 days has emerged as an alternative regimen,[8,10–11] having been used successfully in 2 neonates[8,10] and several adults[11] in whom it appears to be safe and effective. Finally, the addition of azithromycin or atovaquone to the clindamycin hydrochloride plus quinine sulfate regimen has been proposed,[2,8] particularly if parasitemia is slow to resolve.

Recently, our understanding of babesiosis and the methods of testing for it have improved dramatically. Because babesiosis (and congenital babesiosis) is an emerging tick-borne zoonosis, it is worthwhile to review the state-of-the-art approach to its diagnosis in the context of the limitations to diagnosis inherent in this particular case, including its retrospective nature, the mother's lack of insurance and resultant unwillingness to undergo any additional laboratory testing, and the loss to follow-up of the infant and her migrant family.

Diagnosis of congenital babesiosis requires definitive evidence of babesiosis, including evidence from reference laboratory species-specific IFA testing, PCR confirmation, and evidence from reference laboratory evaluation of peripheral blood smears, particularly blood smears with high parasitemia (necessary because of the numerous species of Babesia endemic to the United States, including B. microti, B. divergens–like, B. duncani, MO-1, CA-1, and WA-1). Accurate diagnosis also requires collection of extensive epidemiologic information about patients with suspected infections, including their recent and remote travel history, exposure to ticks, transfusion or transplant. Follow-up for recrudescence is important, particularly for the immunocompromised patient. Our report of a probable third case of congenital babesiosis illustrates the variability in the manifestations and clinical course of the illness, suggesting a need for improvement in how the disease is recognized and for evaluation of current treatment modalities.


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