The spleen plays an important role in the clearance of encapsulated bacteria and of erythrocytes parasitized by protozoa, such as malaria and babesia. A 71-year-old woman with müllerian carcinoma was admitted to the hospital because of fever, fatigue, and myalgias 3.5 weeks after extensive cytoreductive surgery. Anorexia, abdominal pain, and bloating had developed 1 day earlier. Diagnostic studies were performed in a new Case Record.
• What are some of the infectious agents that may be transmitted by blood transfusions?
Transmission of cytomegalovirus through blood transfusion is not uncommon. Dengue, chikungunya, and Zika virus infections may be transmitted through blood transfusion; they usually have incubation periods of 2 weeks or less, and are frequently associated with rash and arthralgia, although they rarely occur in the United States population. Malaria is rarely transmitted through blood transfusion in areas in which the disease is not endemic. The risk of transmission of pathogens for which the blood supply is routinely screened, such as human immunodeficiency virus (HIV), hepatitis B virus (HBV), and hepatitis C virus (HCV), is extremely low.
• Is the blood supply routinely screened for babesiosis?
An infection for which the blood supply is not routinely screened but one that may be transmitted through transfusion is babesiosis, a tickborne zoonotic disease that is caused primarily by Babesia microti in the United States. Babesia is endemic in New England and regions of the upper Midwest, and transmission of babesiosis has been increasingly associated with blood transfusions in recent years. The incubation period for transfusion-related babesiosis ranges from 11 to 176 days (median, 37 days), and the diagnosis is often made unexpectedly, after a routine blood-smear examination.
Morning Report Questions
Q: What are some of the clinical manifestations of B. microti infection?
A: The clinical manifestations of B. microti infection range from asymptomatic infection to severe disease resulting in hemolysis, shock, and death. The risk of severe infection is particularly high among patients who do not have a functional spleen or are immunocompromised. Symptoms such as fatigue, malaise, weakness, fever, nausea, anorexia, myalgias, abdominal pain, and diarrhea are frequently reported. Abnormal laboratory test results, such as thrombocytopenia, hemolytic anemia, and elevated aminotransferase and serum alkaline phosphatase levels, may occur, but none of these results are highly sensitive for the diagnosis of babesiosis.
Q: Can transfusion-transmitted babesiosis be eliminated by taking a thorough history from blood donors?
A: During 2010–2014, babesia species were responsible for 4 of the 15 deaths caused by transfusion-transmitted infections in the United States. Obtaining the donor history is largely ineffective in preventing transfusion-transmitted babesiosis, because 80% of infected persons are asymptomatic and may remain parasitemic for several months. In addition, babesia species survive in red cells that are stored in either liquid or frozen form. In regions in which babesia is endemic, approximately 1 to 2% of blood donors have laboratory evidence of current or past infection, with the prevalence reaching 10% in some hyperendemic areas. Currently, donors are deferred if they have a history of babesiosis or have been implicated in a case of transfusion-transmitted babesiosis. No laboratory tests are currently licensed for donor screening, although several are under development.