Saint Louis encephalitis virus (SLEV)_B

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Record number: 
Adverse Occurrence type: 
MPHO Type: 
Estimated frequency: 
From a blood donation by a donor with an asymptomatic SLEV infection, resulting in a unit of leuko-reduced ed blood cell (RBC) and a unit of fresh frozen plasma, only the recipient of the RBC (kidney transplant recipient) developed SLEV infection. The recipient of the plasma (elderly woman with HUS/thrombotic thrombocytopenic purpura) did not develop signs or symptoms of SLEV infection after the transfusion but she was not tested for SLEV infection. Alhough she may have developed a silent asymptomatic SLEV infection, (90% of those infected by SLEV have asymptomatic infections), the information available does not suggest a plasma-transmitted SLEV infection. Thus this case suggests an "estimated frequency" or risk of transmission by the SLEV-infected donated blood units at 50%.
Time to detection: 
15 days after red blood cell transfusion
Alerting signals, symptoms, evidence of occurrence: 
The kidney recipient received a RBC transfusion infected with SLEV 20 days after transplant. On day 15 after RBC transfusion (35 days after kidney transplantation) the patient experienced headache, fever, rigors, fatigue, nausea, diarrhea, shortness of breath. He developed lower extremity paralysis and respiratory distress on day 17 after transfusion, altered mental status on day 43, and was treated with IVIg and interferon on days 44-48. On day 59 after transfusion his mental status improved and he was discharged on day 105 with residual memory loss and weakness. On examination nine months later, all symptoms of SLEV infection had resolved. The kidney recipient tested negative for IgM anti-SLEV before transfusion but positive when symptoms first developed 15 days later with titer increasing four-fold a week later.
Demonstration of imputability or root cause: 
EVIDENCE OF TRANSMISSION: A symtomatic neuro-invasive SLEV infection developed in a kidney transplant recipient following receipt of a RBC transfusion from a blood donor later proven to have a SLEV infection. The recipient's blood testing for SLEV antibodies and his preceding asymptomatic incubation period were typical for a new SLEV infection. The kidney recipient tested positive for recent SLEV infection (positive for IgM anti-SLEV with titer increasing four-fold a week later) during his very symptomatic clinical SLEV infection following a 15 day, an incubation period expected for SLEV infection of organ recipients. In the general population, the usual asymptomatic incubation period is 5-15 days before the onset of a clinical illness, but the incubation period is a mean of 13.5 days for immune suppressed patients. The asymptomatic blood donor tested confirmed positive for IgM anti-SLEV. Mosquitoes infected with SLEV were found near the blood donor’s home. No mosquitoes captured near the recipient's home or the hospital were infected by SLEV. The patient did not remember being bitten by mosquitoes. Except for one day at home, he was in the hospital the entire period from transplant to his readmission with his symptomatic SLEV infection. The multi-organ donor did not have symptoms of SLEV and his blood and lymph nodes tested negative for SLEV antibodies, antigen and RNA. Two recipients of other organs (heart & kidney) from the same donor did not develop post-transplant symptoms of a SLEV infection and had negative tests for anti-SLEV.. No SLEV was isolated or available from the infected patient, infected blood donor, or mosquitoes found near the blood donor's home, which would, if tested by nucleic acid sequencing and if they matched, confirm the origin from the blood donor and would confirm that the recipient's infection was transmitted from the blood donor.
Imputability grade: 
2 Probable
Suggest new keywords: 
St Louis Encephalitis Virus, Viral Infection, Transfusion Transmiited Infection,, Red Cell Transfusion, mosquito, mosquito-transmitted Infection. Kidney Transplantation, Neuro-invasive infection, Fever, Headache, Flaccid paralysis, Altered Mental Status,
Suggest references: 
St. Louis encephalitis virus possibly transmitted through blood transfusion-Arizona, 2015. Venkat H, et al. Transfusion. 2017 Dec;57(12):2987-2994
ADD Saint Louis encephalitis virus (SLEV) in the AO taxonomy (EP) - OK!
Expert comments for publication: 
This case is the first published report of transmiting SLEV through blood transfusion. It demonstrated convincingly that the infection was neither transmitted from the kidney donor, nor was it a case of reactivation of a latent virus in the recipient. It also demostrrated that the recipient did not acquire the infection from mosquitoes in the environment. It demonstrates the importance of considering blood transfusions as a possible source of a viral infection found in the transplant recipient. When, during the evaluation of post-transplant infections, the organ donor is found to be free of the specific infection, it is important to consider other causes such as reactivation of chronic asymptomatic viral infection in the organ recipient (e.g. CMV, Herpes simplex, EBV, etc), acquisition from the environment or others, research laboratory exposure and exposure to other MPHOs: blood tansfusions, transplants, and gametes.