A risk assessment model for transfusion transmission of dengue.

Dengue virus (DENV) is a disease-causing agent normally transmitted from person to person through the bite of an infected mosquito. In addition to mosquito-borne cases of dengue, there are instances of transmission of dengue after receipt of blood products or donor organs or tissue. To improve blood safety, we developed a quantitative risk assessment model to estimate the dengue risk of transmission to blood transfusion recipients from preclinical and subclinical blood donors. We derived predictive coefficients from model simulations for predicting the risk outcomes such as monthly infectious blood units and transfusion-transmitted DENV cases based on the rate of reported clinical cases. The model was validated with a previous study where donor blood samples from the 2012 dengue transmission season in Rio de Janeiro, Brazil were tested for DENV RNA by a transcription-mediated amplification (TMA) assay. In that study, about 69·4% of donations were tested by the TMA assay and 78 samples were found positive, indicating that 112 DENV RNA-positive donations would have been detected if testing screening had been performed on all donations. Our model estimated a mean of 93 (2.5-97.5th%ile: 47-186) infected units among the donations, which was consistent with the reported numbers.