Public Health Dispatch: Investigations of West Nile Virus Infections in Recipients of Blood Transfusions

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CDC, the Food and Drug Administration (FDA), and the Health Resources and Services Administration (HRSA), in collaboration with blood collection agencies and state and local health departments, continue to investigate West Nile virus (WNV) infections in recipients of blood transfusions. During August 28--October 26, CDC received reports of 47 persons with possible transfusion-related WNV infection. Investigations showed that 14 of these persons either did not have WNV infection or did not acquire WNV infection through transfusion. The remaining 33 cases, reported from 17 states, occurred among persons who had confirmed or probable WNV infection and had received blood components in the month before illness onset. To date, evidence that WNV can be transmitted through blood transfusion has been found in six of the 33 cases; investigations are ongoing for the other 27 cases.

Among the six cases with evidence that WNV can be transmitted through blood transfusion, three have been previously summarized (1,2). Two patients developed confirmed West Nile virus meningoencephalitis (WNME) after receiving different blood components derived from the same blood donation, which was subsequently found to have evidence of WNV (2). In follow-up testing, the donor associated with these components had WNV-specific IgM antibody. On interview, this donor reported having a fever and a rash 2 and 5 days after donation, respectively. In a third case, WNV was isolated from an untransfused unit of fresh frozen plasma (FFP) derived from the suspected donation, indicating that the virus can survive in some blood components (1). The donor of this unit sought medical care 4 days after donation for an illness of 1--2 weeks duration characterized by nasal congestion, sinus pain, headache, malaise, and fatigue and was treated for sinusitis. On follow-up, the donor tested positive for WNV-specific IgM antibody.

Investigations of three additional patients found evidence that these persons acquired WNV infection by transfusion. An adolescent with a hematologic malignancy who had been hospitalized continuously for 65 days developed WNME after receiving 93 blood components in the month before illness onset. Of 72 retention segments* available from these donations, one tested positive for WNV by kinetic quantitative polymerase chain reaction assay (Taqman^®) and negative for WNV-specific IgM antibody. The donor of the unit associated with the Taqman^®-positive retention segment reported fever, chills, headache, painful eyes, and generalized weakness beginning 2 days after donation in early September and subsequently developed WNV IgM antibody.

Two additional patients had WNME diagnosed after each had received a component derived from the same blood donation. The first patient, a man aged 60 years with a malignancy, received 4 units of red blood cells during September 18--30 and subsequently developed encephalitis. Serum and cerebrospinal fluid samples tested positive for WNV-specific IgM antibody on October 8 and 16, respectively; the patient subsequently died. One of four retention segments associated with the units the patient received tested positive for WNV by Taqman^® and negative for WNV-specific IgM antibody. A unit of FFP associated with this Taqman^®-positive donation had been administered on October 6 to the second patient, a woman aged 40 years with a malignancy; 3 days later, this patient had fever. Serum collected from the patient 1 day before transfusion was negative for WNV by Taqman^® and WNV-specific IgM antibody. Serum collected from the patient 9 days after transfusion tested positive for WNV by reverse transcription polymerase chain reaction and negative for WNV-specific IgM antibody; serum collected 6 days later tested positive for WNV by Taqman^® and positive for WNV-specific IgM antibody. The donor of the Taqman^®-positive unit subsequently developed WNV IgM antibody. During follow-up interview, the donor reported having fever, chills, headache, eye pain, and myalgias 5 days before donation and a rash 4 days after donation in late August.

Cases of WNV infection in patients who have received blood transfusions within the month preceding illness onset should be reported to CDC through state and local public health authorities. Serum or tissue samples should be retained for later studies. In addition, cases of WNV infection occurring in persons who have illness onset within 2 weeks after blood donation should be reported. Prompt reporting of these cases will facilitate withdrawal of potentially infectious blood components.

FDA has issued a guidance document for deferral of donors with suspect or diagnosed WNV infection who have illness onset before or after donation (3). In addition, the document provides recommendations for retrieval and quarantine of blood and blood components in such donors. FDA, in collaboration with CDC, the National Institutes of Health, and HRSA, is sponsoring a workshop on development of donor-screening assays for WNV. Additional information on this workshop is available at http://www.fda.gov/cber/meetings/wnv110402.htm.

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