The risk of blood transfusion–associated Chikungunya fever during the 2009 epidemic in Songkhla Province, Thailand

Background Asymptomatic C hikungunya fever ( CHIKF )‐viremic blood donors could be a potential threat of spreading the disease unwittingly through contaminated blood transfusions. The relatively low prevalence of C hikungunya virus antibodies in the population and the records of more than 9000 suspected CHIKF cases raised concern about the potential transfusion‐associated CHIKF during the 2009 epidemic. This study assessed the potential transfusion risk for CHIKF and the implementation of blood safety measures to mitigate this risk. Study Design and Methods A probabilistic model using key variables obtained from local information was used to estimate the weekly risk of transfusion‐associated CHIKF during the 2009 epidemic. In addition, other blood safety measure–based strategies involving screening for donors at risk, donor tracing, and a 7‐day quarantine of blood components at risk were implemented at the time of the epidemic. Results The risk of viremic donations per 100,000 ranged from 38.2 (95% confidence interval [ CI ], 36.5‐39.8) to 52.3 (95% CI , 50.4‐54.2). The potential risk of transfusion‐associated CHIKF per 100,000 was estimated to be 1 in 2429 (0.04%; 95% CI , 1 in 6681 [0.02%]‐1 in 1572 [0.06%]) to 1 in 1781 (0.06%; 95% CI , 1 in 3817 [0.03%]‐1 in 1214 (0.08%]) donations. Among 26,722 donations, 11 (95% CI , 4‐17) to 15 (95% CI , 7‐22) donations were predicted to associate with transfusion risk. The implementation of blood safety measure–based strategies for this epidemic period suggested to deter 11 blood donations of transfusion risk. Conclusion The interventions for blood safety measures applied in this study had mitigated the potential transfusion‐associated CHIKF during the 2009 epidemic.