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Researchers have reported 2 cases in which the Zika virus seems to have been transmitted via platelet transfusion.
Brazilian health officials previously announced 2 cases of Zika virus—in a liver transplant recipient and a gunshot victim—that likely resulted from blood transfusions performed in 2015.
Now, researchers have reported possible transmission via transfusion in 2 more Brazilians—a patient with primary myelofibrosis (PMF) and one with acute myeloid leukemia (AML).
The researchers described these cases in a letter to NEJM.
An individual who donated platelets via apheresis on January 16, 2016, later tested positive for the Zika virus.
On January 19, platelets from that donor were transfused into a 54-year-old woman with PMF and a 14-year-old girl with AML who had also received a haploidentical bone marrow transplant on January 6.
The platelet donor called the blood bank on January 21 to report worrying symptoms—a cutaneous rash, retro-orbital pain, and pain in both knees—that had developed on January 18.
Subsequent testing revealed that the donor was negative for chikungunya and dengue virus. However, both plasma and urine samples tested positive for Zika virus.
Pre-transfusion samples collected from both of the recipients were negative for chikungunya, dengue, and Zika. However, samples collected after the transfusions—6 days after for the woman with PMF and 23 to 51 days after for the girl with AML—tested positive for Zika.
Researchers performed molecular sequencing and phylogenetic analysis of Zika virus RNA isolated from the donor and the recipients. Isolates from all 3 parties had nucleotide changes in the envelope gene (codons 11 and 186) that were not observed among other available isolates from Brazil.
The researchers said these results suggest the platelet transfusions were the source of Zika virus infection in the PMF patient and the AML patient.
Although both patients could have been exposed to Zika-carrying mosquitoes, both the RNA results and the timing of Zika infection suggest the transfusions were the cause.
