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

Background: To 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 Methods: A 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.

Results: The 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.

Conclusion: This study suggests that prompt blood screening measures can reduce the risk of transfusion-transmitted CHIKF and maintain a safe blood supply during an outbreak.