Barbara L. Herwaldt, MD, MPH; Jeanne V. Linden, MD, MPH; Elizabeth Bosserman, MPH; Carolyn Young, MD; Danuta Olkowska, MD; Marianna Wilson, MS
Babesiosis is a potentially life-threatening disease caused by intraerythrocytic parasites, which usually are tickborne but also are transmissible by transfusion. Tickborne transmission of Babesia microti mainly occurs in 7 states in the Northeast and the upper Midwest of the United States. No Babesia test for screening blood donors has been licensed.
To ascertain and summarize data on U.S. transfusion-associated Babesia cases identified since the first described case in 1979.
Case patients were transfused during 1979–2009 and had posttransfusion Babesia infection diagnosed by 2010, without reported evidence that another transmission route was more likely than transfusion. Implicated donors had laboratory evidence of infection. Potential cases were excluded if all pertinent donors tested negative.
Distributions of ascertained cases according to Babesia species and period and state of transfusion.
159 transfusion-associated B. microti cases were included; donors were implicated for 136 (86%). The case patients' median age was 65 years (range, <1 to 94 years). Most cases were associated with red blood cell components; 4 were linked to whole blood–derived platelets. Cases occurred in all 4 seasons and in 22 (of 31) years, but 77% (122 cases) occurred during 2000–2009. Cases occurred in 19 states, but 87% (138 cases) were in the 7 main B. microti–endemic states. In addition, 3 B. duncani cases were documented in western states.
The extent to which cases were not diagnosed, investigated, reported, or ascertained is unknown.
Donor-screening strategies that mitigate the risk for transfusion transmission are needed. Babesiosis should be included in the differential diagnosis of unexplained posttransfusion hemolytic anemia or fever, regardless of the season or U.S. region.
Babesiosis, a parasitic infection transmitted through tick bites, can also be acquired via blood transfusion and may result in life-threatening disease. There is no U.S. Food and Drug Administration–licensed test to screen blood donors for Babesia infection.
The risk for transfusion-associated Babesia infection may be increasing. Cases have occurred year-round and have been seen in states where Babesia species are not endemic.
Although the cases ascribed to transfusion undoubtedly represent a fraction of those that occurred, some tickborne cases inadvertently might have been included.
Improvements in the prevention and detection of transfusion-associated babesiosis are urgently needed.
By type of case (cluster vs. not; index vs. not) and by class of index case (definite, probable, or possible). This figure, in conjunction with Table 1, provides perspective about the criteria for and the tallies of cases, donors, and donations. The 159 B. microti cases include 141 index cases and 18 nonindex, cluster cases. Each index case was associated with a different donor, whether implicated (n = 118) or virtual (n = 23; see Methods section). The 61 index cases classified as definite include the index cases for the 12 multicase clusters (Table 1), which encompass 18 additional cases, for a total of 79 cases. The 3 B. duncani cases are not included in the figure.
By period and state of transfusion. The data are limited to the 141 B. microti index cases, 12 of which were associated with multicase clusters (Table 1). Data for the 3 B. duncani cases, which occurred in Washington (in 1994) and California (in 2000 and 2008), are not included. The x-axis includes one 6-year period (1979–1984), followed by five 5-year periods. See the Methods section for the distinction between the 7 main B. microti–endemic states and “other states”; within each category, for the tallies by state (by period), the states generally are listed in the order of their first identified case.
* Local and intraregional movements of donors and blood components were common both in the Northeast and in the upper Midwest (data not shown).
† Among the 19 index cases in 12 “other states,” the North Carolina case and 1 Florida case were not linked to donors, the other Florida case was linked to a Wisconsin resident who donated blood while wintering in Florida (cluster K in Table 1), and 1 of 3 Pennsylvania cases was linked to a Pennsylvania donor who reportedly had not traveled to a known B. microti–endemic area in another state (8). Information on the donors linked to the other 15 index cases is provided in the text or the footnotes below for 7 and 8 cases, respectively.
‡ The donor was exposed in Massachusetts (32).
§ The 4 index cases in Maryland and Virginia were linked to donations in these states. The linked donors either were or could have been exposed in the Northeast.
|| The cases in Ohio (n = 2) and Indiana (n = 1) were linked to donations in Indiana (n = 2) and Ohio (n = 1) by donors exposed in B. microti–endemic states.
The month of donation was known or estimable for 128 of 148 donations (by 141 donors) associated with transmission (Figure 1). The 19 donations by the 12 donors linked to multicase clusters occurred in 10 different months. If applicable, the month of donation was approximated by subtracting 16 days (the median age of liquid-stored red blood cells at the time of transfusion; see text) from the transfusion date. The donations linked to the 3 B. duncani cases occurred in April (n = 2) and August (n = 1); these data are not included.
The data are limited to the subsets of the 141 index patients for whom particular intervals were relevant and were known or estimable (for example, the incubation period was unclear for some patients who had comorbid conditions or altered mental status). Each box represents the interquartile range (IQR), the internal vertical line indicates the median, the whiskers show the minimum and maximum, and the dots indicate the outliers with the longest intervals (≥75% quartile plus 1.5 × IQR). The 21 total dots—5 (6%), 6 (9%), 8 (7%), and 2 (10%) for the first, second, third, and fourth intervals from the top, respectively—are accounted for by 8 case patients, all of whom were linked to a donor. The farthest outliers include a patient with sickle cell disease who received hematopoietic progenitor cells from a sibling with sickle trait and became symptomatic approximately 6 months after the implicated peritransplantation transfusion (28) and 2 of 3 patients who underwent posttransfusion splenectomy (see text). The second interval from the top reflects the posttransfusion hospitalization during which babesiosis was explicitly diagnosed, for patients who had been discharged at least once in the interim or had been transfused as outpatients but were hospitalized thereafter. The fourth interval includes data for 21 of 27 index patients known to have died, including the kidney donor who died on the day he was transfused (see text). This interval was greater than 90 days for 2 immunocompromised patients whose intervals from diagnosis to death were less than 60 days. The patient who underwent splenectomy 215 days after transfusion died 280 days after transfusion; the patient's lymphoma also relapsed. For patients with available data, the median interval from symptom onset to death was 10 days (range, 2 to 51 days; n = 18) and the median interval from diagnosis to death was 7 days (range, 0 to 55 days; n = 22).
Herwaldt BL, Linden JV, Bosserman E, et al. Transfusion-Associated Babesiosis in the United States: A Description of Cases. Ann Intern Med. 2011;155:509–519. doi: https://doi.org/10.7326/0003-4819-155-8-201110180-00362
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Published: Ann Intern Med. 2011;155(8):509-519.
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