Rationale:

• Infectious blood products from asymptomatic viremic blood donors can transmit WNV when transfused into immunosuppressed and nonimmunosuppressed persons.
• Infectious solid organs can transmit WNV when transplanted into immunosuppressed persons.

Evidence:

• Patients contracted WNV infection by transfusion in a 2002 case series study (7).
• WNV was transmitted via organ transplantation from a viremic donor in a 2002 study of four transplant recipients (8).
• WNV was transmitted via organ transplantation from a nonviremic, IgM-positive donor to three of four organ recipients in a 2005 study (9).

Comments:

• The conditions that would allow WNV transmission through organ transplantation are likely to be found in situations in which living persons are donating.
• In cadaveric donors, the potential value of deferral and screening has yet to be determined.
• Blood banking recommendations come from 2003 FDA guidelines (10).
• The instance of organ transplant-associated transmission from a nonviremic, IgM-positive donor suggests that transmission can occur from WNV sequestered in organs.
• Some residual risk of blood transfusion-related transmission exists; however, blood centers attempt to minimize this risk by switching from mini-pool to individual donation screening in epidemic areas.