OneBlood, Inc. St. Petersburg, Florida, United States
Background/Case Studies: Transfusion-transmitted malaria (TTM) is rare in the U.S., with fewer than 1 case per 10 million donations. However, from May to July 2023, a Plasmodium vivax cluster involving five contiguous ZIP codes in Sarasota County, Florida, resulted in seven autochthonous cases within ~35 square miles. Local mosquitoes remain competent vectors during summer, and infected donors may develop symptoms after donation. In the absence of an FDA-approved donor screening test, the local blood center (BC) activated its Vector-borne Pathogen Mitigation Strategy (VPMS), a tiered, risk-based framework developed over more than a decade to protect the blood supply from mosquito-borne pathogens including dengue, chikungunya, Zika, and malaria.
Study
Design/Methods: The VPMS uses color-coded geographic classifications based on collection region, county, ZIP code, and case counts to scale interventions. These include enhanced donor education and questioning, product quarantine with follow-up, scripted callbacks, and amotosalen/UVA pathogen reduction for platelets. Oversight and escalation is made in consultation with health authorities. The VPMS was triggered from May 27 to November 1. To evaluate potential silent parasitemia, 436 retained samples from eligible donors were retrospectively NAT tested for malaria as follows: 258 samples from donors residing in 4 impacted Sarasota zip codes collected from July 5 to September 17 and 178 samples collected between August 1 to October 6 from eligible donors residing in nonmalaria Miami areas during and after a dengue outbreak. All samples were tested using the Procleix Plasmodium Assay (Grifols), a CE marked TMA assay detecting 18S rRNA from five Plasmodium species.
Results/Findings: VPMS was previously applied during dengue (2013, 2014), chikungunya (2014), Zika (2016-2021), and malaria (2023) outbreaks, enabling targeted interventions. No known transfusion-transmitted infections occurred. All 435 valid samples from the 2023 malaria-affected (258 samples) and non-malaria regions (178 samples) tested nonreactive by TMA.
Conclusions: This experience illustrates the value of a structured, scalable, geographically targeted risk mitigation strategy in a subtropical U.S. region. By tailoring interventions to local public health data and pathogen risk, the BC preserved blood availability while protecting transfusion safety. The system minimized unnecessary donor loss and product discard and offers a reproducible model for other centers. The 2023 malaria event marked the first VPMS implementation of retrospective nucleic acid testing as a confirmatory surveillance tool, reinforcing the platform’s scalability and utility during emerging vector-borne outbreaks.
