West Nile Virus Transmission via Organ Transplantation and Blood Transfusion — Louisiana, 2008

E Stanley, MPH; R Ratard, MD; JE Staples, MD; R Royce, WA Bower, MD; KD Ellingson, PhD; MJ Kuehnert, MD


Morbidity and Mortality Weekly Report. 2009;58(45):1263-1267. 

In This Article

Organ Transplant

On October 23, 2008, LDH was notified of a transplant recipient with suspected WNND (Table). The patient, a man aged 62 years, had undergone a heart transplant on September 23, 2008, because of hypertrophic cardiomyopathy and congestive heart failure. The patient had an uneventful postoperative course until the eighth day after his transplantation, when he had tonic-clonic seizures requiring intubation and transfer to the intensive-care unit (ICU). In the ICU, the patient was febrile (101°F [38°C]) with a normal peripheral white blood cell (WBC) count (8.33 × 109/L) and blood chemistries. He was treated empirically with a combination of piperacillin and tazobactam for possible bacterial infection. He was extubated the next day, but his mental status continued to deteriorate. Because neurologic complications occurring in patients after transfusion or organ transplantation can result from donor-related WNV transmission,* specimens from the patient were tested for WNV infection. Serum and cerebrospinal fluid (CSF) obtained 22 days (October 15) and 31 days (October 24) posttransplantation, respectively, were positive for WNV immunoglobulin M (IgM) antibodies by enzyme-linked immunosorbent assay (ELISA) performed at a commercial laboratory. Testing at CDC on a serum specimen obtained 43 days posttransplantation showed WNV-specific neutralizing antibodies with a titer of 20,480 (positive titer ≥10), confirming the WNND diagnosis.

A pretransplant serum specimen tested negative for WNV RNA by reverse transcription–polymerase chain reaction and negative for WNV IgM and immunoglobulin (IgG) antibodies, suggesting the patient's infection occurred around the time of the transplantation. At discharge on December 17, 2008, he was unable to walk without assistance and was transferred to a skilled nursing facility for rehabilitation; he was discharged from that facility on January 9, 2009, to continue physical therapy as an outpatient.

The recipient reported that, before his heart transplantation, he went outside his home infrequently and applied mosquito repellent when going outside. He did not recall any mosquito bites before his hospitalization. Perioperatively, he received 10 blood products from 16 donors while on cardiopulmonary bypass pump. Blood from these donations was not available for testing. Eight of the 16 donors were contacted successfully and voluntarily agreed to testing; all eight were WNV IgM negative by ELISA.

The heart donor, a man aged 18 years, was admitted to the hospital with a gunshot wound to the head on September 21, 2008. He received 10 blood products before being declared brain dead on September 23. His heart was the only organ or tissue procured. After potential donor-related WNV transmission was recognized on October 15, donor serum collected at the time of heart donation and after receipt of blood products was tested by both a commercial laboratory and CDC, and was negative for WNV RNA and WNV IgM and IgG antibodies. All blood donations received by the heart donor were tested by the blood screening laboratory used by blood center A and were negative by WNV minipool nucleic acid-amplification testing (MP-NAT) on pools of 16 samples. The blood screening laboratory used by blood center A at the time of these donations had not met its criteria for switching from MP-NAT to individual donation NAT (ID-NAT)§ (Figure). All blood donors were contacted and returned for WNV IgM screening; nine tested negative for WNV IgM and IgG at a reference laboratory. One blood donor's serum collected 8 weeks after donation tested positive at CDC for WNV IgM antibodies and WNV-specific neutralization antibodies with a titer of 1:640, indicating recent WNV infection.


Strategies used by laboratories to screen donated blood for West Nile virus (WNV) — Louisiana, 2008
* Blood centers generally pool blood samples for screening until WNV is identified in one or more samples. Established criteria for switching from MP-NAT to ID-NAT can vary greatly between blood centers. Some centers transition from MP-NAT to ID-NAT after identification of two MP-NAT positive donations from donors living in the same postal code area within a 7-day period. Other centers transition to ID-NAT if one donation is identified as positive by MP-NAT at any blood center within their collection area. When the established criteria are met, all donations then are screened by ID-NAT until no positive donations are detected for a predetrimined period (usually 7 days); then they transition back to MP-NAT.

* Although most WNV infections are asymptomatic, approximately 20% of infected persons develop a self-limited febrile illness after an incubation of 3–6 days. Incubation periods up to 1 month have been documented after blood transfusion and organ transplantation.[2,3] Less than 1% of infected immunocompetent persons will develop more severe neuroinvasive disease (e.g., encephalitis, meningoencephalitis, meningitis, or poliomyelitis-like acute flaccid paralysis). However, as many as 40%–60% of immunocompromised persons infected as a result of receiving a WNV-infected organ develop neuroinvasive disease.
WNV infections typically are diagnosed based on serologic testing and detection of WNV immunoglobulin M (IgM) and neutralizing antibodies in serum or cerebrospinal fluid. WNV IgM antibodies are normally detected within 8 days of illness onset in immunocompetent persons. Nucleic acid-amplification testing (NAT) detects the presence of WNV before development of WNV IgM antibodies and is used by blood centers to screen for WNV in donated blood. WNV screening by blood centers is performed on pooled samples (i.e., minipool NAT [MP-NAT]). Individual blood centers have differing criteria for switching to individual sample testing (ID-NAT) when a positive MP-NAT is detected.
§ Two MP-NAT positive donations from the same postal code area within a 7-day period.


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