Seasonal increase in syphilis screening reactivity rates in whole blood donors, United States, 2011-2023.

BACKGROUND: In December 2021, the U.S. Food and Drug Administration published a letter to clinical laboratory staff and healthcare providers detailing a risk of false Rapid Plasma Reagin (RPR) when using the Bio-Rad Laboratories BioPlex 2200 Syphilis Total & RPR kit in people who had received COVID-19 vaccination; Treponema pallidum particle agglutination assays did not appear to be impacted by this issue. We evaluated reactivity rates of syphilis screening with negative confirmatory testing at our institution by year and seasonality. METHODS: We performed a retrospective study of routine syphilis testing of whole blood (WB) collections at an academic hospital-based donor center in the eastern United States. All WB donations from 2011 to 2023 which demonstrated reactive syphilis screening (Beckman Coulter PK TP Microhemagglutination) with negative confirmatory testing (CAPTIA Syphilis (T. pallidum)-G) were evaluated. Reactivity rates by year and season of donation were compared using unpaired t-tests. RESULTS: A total of 109 WB donations from 86 unique donors who donated from 2011 to 2023 screened reactive for syphilis with negative confirmatory testing. The unconfirmed syphilis reactivity rate increased from 2018 to 2023 (mean: 0.360%) compared to 2011-2017 (mean: 0.071%, p < .05). An autumnal peak in unconfirmed reactives was observed. CONCLUSION: The unconfirmed syphilis reactivity rate among WB donors at our institution increased markedly since 2017 compared to the 7 years prior and doubled from 2020 to 2021. No testing assay changes explain these results. The autumnal peak in unconfirmed reactives suggests a possible environmental trigger such as viral infection or vaccination.

Consideration for alpha-gal syndrome in two critically ill persons with group O blood who received group B plasma.

BACKGROUND: The U.S. Centers for Disease Control and Prevention (CDC) has reported increasing rates of alpha-gal syndrome, an allergic response after meat ingestion (AGS). AGS has been associated with prior exposure to tick bites or other biologics characterized by a life-threatening immunoglobulin E (IgE)-mediated hypersensitivity to galactose-alpha-1,3-galactose (alpha-gal) an oligosaccharide structurally similar to the group B antigen on red blood cells (RBC) found in most non-primate mammalian meat and products derived from these mammals. In 2023, Transfusion reported 3 group O recipients of group B plasma in the Washington, D.C. metropolitan area with no history of meat allergy who had anaphylactic transfusion reactions compatible with AGS. AIMS: We investigated allergic reactions in 2 additional patients who received ABO minor-incompatible blood products at 2 hospitals in the D.C. area during fall 2023. METHODS: For both patients, a medical chart review was performed and IgE levels to alpha-gal were measured. RESULTS: The first patient, a 64-year-old, O-positive patient status post heart transplant with no known allergies, was admitted with acute COVID-19 induced antibody-mediated transplant rejection and placed on extracorporeal membrane oxygenation (ECMO). While undergoing plasma exchange (PLEX) (50% albumin/50% fresh frozen plasma (FFP)), the patient tolerated 2 units of group O FFP and 1 unit of group A FFP before becoming hemodynamically unstable during transfusion of 1 unit of B-positive FFP. PLEX was stopped. The patient later died of sepsis from underlying causes. The second patient, a 57-year-old O-positive man with a history of melanoma and neuro fibromatosis type 1, was undergoing an abdominal resection including transfusion of 3 units of O-positive RBC when he suffered hypotension and ventricular tachycardia requiring intraoperative code after receiving 2 units of group B FFP. Hiveswere noted after resuscitation. The patient had a history of tick bites but no known allergies. He is alive 5 months after the possible allergic event. Both patients had full transfusion reaction evaluations and immunology testing results above the positive cutoff for anti-alpha-gal IgE. DISCUSSION AND CONCLUSION: Two patients with O-positive blood and no known allergies experience danaphyl axis after transfusion with group B FFP. The symptoms cannot definitively be imputed to an allergic transfusion reaction, but the presence of IgE against alpha-gal supports an association. Medicating patients with antihistamines and IV steroids pre-transfusion may prevent allergic reactions. Restricting group B plasma-containing products (plasma, platelets, cryoprecipitate) for patients who experience AGS-like symptoms may be considered.

An outbreak of anaphylactic transfusion reactions to group B plasma and platelets and its possible relationship to Alpha-Gal syndrome.

BACKGROUND: Alpha-gal syndrome (AGS) is a potentially life-threatening acquired meat allergy associated with tick bites. The allergen Galactose-α-1,3-Galactose is antigenically similar to the B blood group antigen. B blood group status offers some protection against development of the allergy. Although not preferred practice, transfusion of plasma and platelets from group B donors is believed to be safe for group O recipients. STUDY DESIGN AND METHODS: Anaphylactic transfusion reactions were reported for three patients in two Washington DC hospitals from Nov 2022 to February 2023. A chart review was performed for all three patients. Patients or family members were interviewed, and IgE levels to alpha-gal were measured in two of the three patients. RESULTS: One reaction was acutely fatal. All reactions were to blood group B Plasma or Platelets in blood group O recipients. One patient had two prior anaphylactic reactions to group O RBCs and group B Plasma in a previous admission. All patients came from southern Maryland where AGS is an emerging problem. Two patients had histories of tick bites, previously unexplained gastrointestinal complaints, and abnormal elevated levels of IgE to alpha gal. Two patients had cat allergies. DISCUSSION: AGS is an emerging problem which may have implications for blood transfusion practice. Avoidance of blood group B antigen containing components may be prudent in non-blood group B patients with established AGS. Investigation for AGS should be considered in the evaluation of anaphylactic transfusion reactions.