Neonatologists should keep transfusion-related babesiosis on the radar

Simonsen KA. Pediatrics. 2011;doi:10.1542/peds.2010-0502.

Seven premature infants contracted Babesia microti infection through split-unit blood transfusions; therefore, neonatologists should take special care to be mindful of this infection in this high-risk group of patients, according to a report published online this month.

Kari A. Simonsen, MD, of the University of Nebraska Medical Center, and colleagues reported on two different clusters of patients from a neonatal ICU in the Northeast.

In the first cluster, four infants who received blood transfusions from the same donor were infected. All of the infants were treated with antibiotics. In that cluster, the researchers said although the peripheral blood of the mother and twin sibling of the index patient tested negative for parasites, and peripheral blood smears from donor blood were negative, an indirect fluorescent antibody test yielded a positive result for B. microti. The second cluster, which involved three extremely premature infants, also involved a single infected donor.

Common symptoms included respiratory distress requiring reintubation, edema, hepatosplenomegaly, fever, hemolytic anemic and thrombocytopenia, according to the researchers. They said the symptoms of infection were difficult to differentiate from sepsis.

“When transfusion-associated babesiosis is diagnosed, prompt notification to the blood bank and testing of all exposed infants is necessary,” the researchers said, adding that antibiotic therapy may need to extend beyond the standard 7 to 10 days to ensure parasitemia resolution.

“Double-volume exchange blood transfusion effectively reduces the parasite load in premature infants,” they said.

Simonsen and colleagues said blood banks do not routinely screen for this infection, so transfusion-related babesiosis is common among adult populations.

Disclosure: The researchers report no relevant financial disclosures.

Eugene D. Shapiro

Babesiosis is an emerging infection about which we are likely to hear with increasing frequency. This report highlights some of the features of this infection that make diagnosis and prevention difficult, especially for transfusion-related infection. Babesia microti usually is transmitted by Ixodes ticks - the same tick that transmits Borrelia burgdorferi bacteria, the cause of Lyme disease.

Babesia are parasites which, like Plasmodia that cause malaria, infect red blood cells. However, in most immunologically normal individuals, infection causes mild or non-specific symptoms, so a high level of suspicion is needed for diagnosis (usually done by microscopy of thick smears of blood). Moreover, most normal individuals clear the infection without requiring treatment with anti-parasitic drugs.

Detection of the parasite by standard microscopy may be particularly difficult in patients with a low burden of parasites. However, illness caused by Babesia can be severe, and even fatal in immunologically compromised individuals, such as those without a spleen and in premature infants. These outbreaks emphasize the need for enhanced awareness of transfusion-associated babesiosis as a cause of disease in this setting.

Eugene D. Shapiro, MD
Infectious Diseases in Children Editorial Board member

Disclosure: Dr. Shapiro reports no relevant financial disclosures.

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