WNV is a neurotropic flavivirus. Humans are accidental, dead-end hosts for WNV. Symptoms usually develop 2-15 days after exposure and viremia begins prior to symptoms onset and ends within a week. However, it is possible to isolate WNV and/or detect RNA or viral antigen in cerebrospinal fluid, tissue, and other body fluids several weeks or years after viremia cession. Since 2003 the highest number of WNV cases reported annually to CDC occurred in 2012. As of 11/20/2012 5,207 cases, including 234 deaths, have been reported to CDC (80% were from 13 states, 30% from Texas). Nationwide in 2008, 11 (19%) of 58 OPOs performed WNV NAT screening. These OPOs differ in their screening strategies and NAT performed. Our recent data shows that organ donors with evidence of recent exposure to WNV are more common than expected and we have also shown that WNV serological evaluation complements WNV NAT. In 2009, our laboratory offered WNV testing to all Organ Procurement Organizations (OPO) we serve.

Aim To share WNV epi data obtained during 2012 from 4 OPOs located in California and Nevada.

Methods Between 01/12 and 11/12 we tested 638 donors from 4 OPOs. All OPO’s elected to screen their donors year long. We used FDA approved EIA for IgM anti-WNV (Focus Technologies, Los Angeles), with confirmatory Plaque Reduction Neutralization Assay (PRNT) and WNV RNA Procleix NAT (Gen-Probe, San Diego).

Results We detected no WNV RNA positive donors. Five donors were IgM anti-WNV reactive and confirmed by PRNT. All resided in California. Two donors had symptoms compatible with acute WNV infection. The 0.78 % of seropositive donors in 2012 was significantly higher (p<.0001; F-test) than in previous years (0.0% – 0.18%).

Conclusions In contrast to previous years, in 2012 we identified significantly higher number of seropositive WNV cases in California. Our algorithm consisting of NAT+IgM WNV screening potentially prevented multiple transmissions of WNV.

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