Risk of transfusion-transmitted chikungunya infection and efficacy of blood safety implementation measures: experience from the 2009 epidemic in Songkhla Province, Thailand

BACKGROUNDTo date, neither is there a standard guideline for maintaining a safe blood supply during a chikungunya fever (CHIKF) outbreak nor has a study been performed on actual transfusion-transmitted CHIKF to recipients. This study estimated the potential incidence of transfusion-transmitted CHIKF and compared the efficacies of various blood safety intervention strategies to mitigate the transfusion-transmitted CHIKF risk. STUDY DESIGN AND METHODSA Web-based tool named the European Up-Front Risk Assessment Tool (EUFRAT) was used to estimate the risk of transfusion-transmitted CHIKF using data inputs from the 2009 Songkhla epidemic in Thailand. RESULTSThe mean and maximal risks of viremic donations during the entire epidemic period were estimated to be 0.9 (95% confidence interval [CI], 0.0-2.7) and 4.8 (95% CI, 0.5-9.1), respectively. This meant that the potential risk of transfusion-transmitted CHIKF to recipients receiving all infective end products in the absence of blood safety measures was from 10.9 (95% CI, 1.8-20.4) to 57.6 (95% CI, 36.4-79.5). Based on experience from the 2009 Thai epidemic, the proportion of 10% asymptomatic cases, for instance, with predonation screening for CHIKF-related symptoms and follow-up observation in donors at risk was estimated to be 88.4% (95% CI, 69.9%-100.0%) to 99.1% (95% CI, 79.6%-100.0%) effective in reducing this transfusion risk compared to 83.7% (95% CI, 65.8%-100.0%) to 90.7% (95% CI, 72.1%-100.0%) by predonation screening for donors at risk of chikungunya virus infection alone. CONCLUSIONThis study suggests that prompt blood screening measures can reduce the risk of transfusion-transmitted CHIKF and maintain a safe blood supply during an outbreak.