A Febrile Blood Donor

A 4-day-old neonate born prematurely at 29 weeks gestation developed thrombocytopenia (platelet count 43 × 109/L) with associated severe pulmonary and intracranial hemorrhaging. Urgent transfusions with 10 mL/kg of packed red cells and 10 mL/kg of platelet concentrate were given. These were sourced from blood donated 2 days earlier in Singapore by a 21-year-old female university student who was clinically well at the time. The day after these blood products were given to the neonate, the blood donor contacted the blood transfusion service to inform them that she was now sick with a febrile flu-like illness. Her blood donation screening plasma sample was retrieved and tested by PCR for several viruses, including dengue, chikungunya, enterovirus, and Epstein-Barr virus.Dengue RNA (serotype 2) was found to be present at a very low amount (i.e., at a real-time PCR cycle Ct number of 39–40) (Fig. 1A⇓ ) from the initial RNA extract (extract A). To confirm the presence of this low amount of dengue 2 RNA, the same extract (extract A, which had been stored at −20 °C) was retested (Fig. 1B⇓ ), and again found to give a low-positive result. Figure 1. Real-time dengue RNA PCR outputs for the donor plasma sample. (A), Real-time PCR results on the RNA extract (extract A, first test) obtained from the first donor sample showing a Ct of 39.6, a low-level positive signal for dengue serotype 2 RNA. (B), Repeat testing on extract A after 1 cycle of freeze-thawing (from −20 °C), showing a higher Ct of 40.8, indicating an even lower amount of RNA present. The normal real-time PCR output is seen as a sigmoidal plot. The Ct value is where the signal sigmoid curve (indicating accumulation of the specific dengue PCR product) crosses the threshold (green horizontal line) indicating a positive …