Babesia divergens

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Record number: 
Adverse Occurrence type: 
MPHO Type: 
Estimated frequency: 
Babesia transmission via blood tranfusion is not rare, but the exact incidence is unknown because symptoms are mild in many immune-competent hosts and the infection may not be noted. Having that said, according to a 2019 FDA guidance document, "Babesiosis can be transmitted by transfusion of blood and blood components, with the first U.S. case of transfusion transmitted babesiosis (TTB) reported in 1980. Since then, more than 200 TTB cases have been documented. While B. microti remains the major causative agent, three TTB cases have been attributed to B. duncani (Ref. 2) and one possible case to B. divergens in the U.S." It is likely that the documented transfusion-transmitted cases do not represent all transfusion-transmitted cases. The frequency of B divergens as a transfusion-transmitted infection appears much less common than B. microti based on paucity of case reports. Babesia divergens causes a severe form of human babesiosis in Europe, which usually occurs in people who have had a splenectomy and is often fatal. Babesiosis was also identified in splenectomized people from Italy and Austria with a new strain (EU1) that was more closely related to Babesia odocoilei. Identical isolates of Babesia have been found in Ixodes ricinus ticks from Slovenia, suggesting a more widespread distribution of this organism in Europe. (Ref. Science Direct).
Time to detection: 
This infection was found incidentally during a medical workup, and even after the investigation it is not clear when the individual was infected. If the blood tranfusion was the source of the B. divergens infection, the blood tranfusion from the donor with antibodies to Babesia occurred only two days prior to detecting the organisms in a blood smear.
Alerting signals, symptoms, evidence of occurrence: 
Because this case was found incidentally, and the source of infection could have been a blood donor but seems circumstantially more likely to have been reactivation from a prior infection, review of other Babesiosis cases is recommended (see Notify records n. 1348, 1350, and 1705).
Demonstration of imputability or root cause: 
Investigation included reviewing for source of tick exposure (none clearly found), and investigation of blood donors because of transfusions during hospital stay. One donor had antibodies to Babesia, and the tranfusion from that donor was 2 days prior to seeing the agent on blood smear Giemsa stain. Further investigation included finding and testing blood of the impacted individual prior to the blood transfusions, and there were antibodies to Babesia in the impacted individual prior to the blood transfusion. Furthermore, there was no IgM, only IgG present, and the individual's overall clinical picture significantly improved with treatment. While transfusion-transmission cannot be entirely ruled out (the blood donor could not be located for follow up investigation or testing), this more likely represents resurgence of prior infection in an individual newly diagnosed with HIV after splenectomy in response to an episode of hemophagocytic syndrome.
Imputability grade: 
1 Possible
Suggest references: 
First report of Babesia divergens infection in an HIV patient. Gonzalez LM et al. Int J Infect Dis. 33:202-4, 2015 Apr. MG: The above is the same reference as being reviewed for this record. The following paper is cited in an FDA guidance document for TT Babesia (published in 2019) that should also be referenced and included here as examples of B. divergans transmission cases (neither of which have high imputability scores). Herwaldt, B.L., et al., Babesia divergens-like infection, Washington State. Emerg Infect Dis, 2004. 10(4):622-629. Reference for the case report referred to in the 2004 article: Herwaldt BL, Kjemtrup AM, Conrad PA, Barnes RC, Wilson M, McCarthy MG, Sayers MH, Eberhard ML. Transfusion-transmitted babesiosis in Washington State: first reported case caused by a WA1-type parasite. J Infect Dis. 1997 May;175(5):1259-62. doi: 10.1086/593812. PMID: 9129100.
MG: A subsequent publication in an FDA guidance listed the following, and it was listed as a possible TTI. I think this case is similarly weak, and its interest is more relevant that an HIV positive individual in Europe developed babesiosis. I do think it is useful to keep in the library just to zip up reports related to various Babesia species. Herwaldt, B.L., et al., Babesia divergens-like infection, Washington State. Emerg Infect Dis, 2004. 10(4):622-629.
Expert comments for publication: 
Various species of Babesia have been transmitted via blood transfusion (see Notify records n. 1348, 1350, and 1705), while this was a rare report of possibly (but not likely) transfusion-transmitted B. divergens.