An unusual nosocomial outbreak of transfusion transmitted Japanese encephalitis

Abstract

Japanese encephalitis virus (JEV) is a mosquito-borne flavivirus endemic in China and Southeast Asia. Although neurological manifestations are observed in less than 1% of infected patients, encephalitis caused by JEV is a devastating condition. About 20-30% patients who develop encephalitis succumb, while 30%-50% of survivors suffer permanent neurologic, cognitive, or psychiatric sequelae. The main route of transmission of JEV is mosquito-borne transmission. In contrast, transfusion transmitted JEV infection has never been reported in the literature, although this potential has been recognized. In this study, we report transmission of JEV via transfusion of cellular blood components (packed red cells and platelets) from an asymptomatic viremic donor to two immunocompromised recipients. The first recipient was a patient with double lung transplantation on high-dose immunosuppressive drugs who developed severe encephalitis as evidenced by compatible cerebrospinal fluid abnormalities and characteristic magnetic resonance imaging scan features performed ten days after symptom onset. JEV RNA was detected in his serum, cerebrospinal fluid and bronchoalveolar lavage fluid specimens. His conscious level progressively deteriorated and had poor neurological recovery. The remnant of the transfused blood product received by the first recipient tested positive for JEV RNA by both real-time RT-PCR and conventional hemi-nested PCR. Sequencing of the amplicons obtained by conventional PCR yielded a sequence identical to that obtained from the index patient. In response to this unusual case of transfusion transmitted JEV infection, we conducted an outbreak investigation and detected a related case of asymptomatic JEV acquisition via transfusion of platelets. The second recipient was a patient with leukemia who had asymptomatic infection. JEV infection was confirmed by IgM seroconversion. This study illustrates that, similar to other human-pathogenic flaviviruses, JEV can be transmitted via blood products. Screening for JEV RNA in donated blood products may need to be considered in endemic areas.