West Nile virus infections projected from blood donor screening data, United States, 2003

Emerg Infect Dis. 2006 Mar;12(3):395-402. doi: 10.3201/eid1205.051287.


National blood donor screening for West Nile virus (WNV) RNA using minipool nucleic acid amplification testing (MP-NAT) was implemented in the United States in July 2003. We compiled national NAT yield data and performed WNV immunoglobulin M (IgM) testing in 1 WNV-epidemic region (North Dakota). State-specific MP-NAT yield, antibody seroprevalence, and the average time RNA is detectable by MP-NAT were used to estimate incident infections in 2003. WNV donor screening yielded 944 confirmed viremic donors. MP-NAT yield peaked in August with >0.5% of donations positive for WNV RNA in 4 states. Peak IgM seroprevalence for North Dakota was 5.2% in late September. The average time viremia is detectable by MP-NAT was 6.9 days (95% confidence interval [CI] 3.0-10.7). An estimated 735,000 (95% CI 322,000-1,147,000) infections occurred in 2003, with 256 (95% CI 112-401) infections per neuroinvasive case. In addition to preventing transfusion-transmitted WNV infection, donor screening can serve as a tool to monitor seasonal incidence in the general population.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Blood Donors*
  • Humans
  • Incidence
  • Mass Screening*
  • RNA, Viral / blood
  • Seasons
  • Sensitivity and Specificity
  • Time Factors
  • United States / epidemiology
  • West Nile Fever / blood*
  • West Nile Fever / epidemiology*
  • West Nile virus / isolation & purification


  • RNA, Viral