Detection of West Nile virus in the Mexican blood supply.
BACKGROUND
West Nile virus (WNV) is the etiologic agent of an emerging disease in the Western Hemisphere that can be transmitted to humans by blood transfusion. WNV first appeared in the United States in 1999, in Canada in 2001, and in Mexico in 2002. The aim of this nationwide study was to determine the prevalence of WNV in blood donors in Mexico as a first step in preventing its transfusion-associated transmission.


METHODS
In July and August 2004, a total of 3856 fresh plasma specimens collected from each state's center for blood transfusion in 29 of 31 Mexican states were screened with an investigational WNV assay (Procleix,(R) Gen-Probe Inc. and Chiron Corp.), a nucleic acid test based on transcription-mediated amplification (TMA). Reactive specimens were confirmed with a second TMA-based test, the alternative WNV assay (Gen-Probe), and with WNV capture enzyme-linked immunosorbent assays (ELISAs) for detection of immunoglobulin M (IgM) and IgG antibodies. In addition, 3714 frozen plasma samples collected in 2002 and 2003 were similarly tested.


RESULTS
One of 3856 fresh samples from an asymptomatic donor from Chihuahua was reactive by both TMA-based tests and IgM ELISA, suggesting a recently acquired infection. The observed percentage of viremic donors blood donors was 0.03 percent. Results from frozen samples were not included in the prevalence calculation and none were TMA-reactive for WNV.


CONCLUSIONS
WNV is present in the Mexican blood supply and measures should be taken to reduce the risk of transfusion transmission.
Sánchez-Guerrero
Sergio A
SA
National Center for Blood Transfusion, Mexico City, Mexico. sasanche@avantel.net
Romero-Estrella
Sagrario
S
Rodríguez-Ruiz
Antonio
A
Infante-Ramírez
Lilia
L
Gómez
Angélica
A
Villanueva-Vidales
Eduardo
E
García-Torres
Martha
M
Domínguez
Ana M A
AM
Vázquez
Jaime A
JA
Calderón
Eva D
ED
Valiente-Banuet
Leopoldo
L
Linnen
Jeffrey M
JM
Broulik
Amy
A
Harel
William
W
Marín Y López
Rafael A
RA
D000914:Antibodies, Viral / Q000097:blood*; D001769:Blood / Q000821:virology; D001771:Blood Banks; D001782:Blood Donors; D001803:Blood Transfusion; D021821:Communicable Diseases, Emerging / Q000097:blood* / Q000517:prevention & control; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D008800:Mexico; D012367:RNA, Viral / Q000097:blood*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014901:West Nile Fever / Q000097:blood* / Q000517:prevention & control / Q000635:transmission; D014902:West Nile virus
D000914:Antibodies, Viral; D012367:RNA, Viral