Flores, M

Flores, M.A. and terns, are candidates for carrying WNV from North America to South America due to long lasting high-level viremias, occasional prolonged infectious viral loads in skin, and direct, long-distance flights. WNV spread southward from the United States to northern South America between 1999 and 2004 following a stepping stone pattern, consistent with spread by birds. Moreover, introduction of WNV into Argentina by migratory birds could explain the presence of the virus in many places in a brief period. However, for migratory birds (211 serum samples tested) in this study, serologic test results were negative. The high titers of WNV-reactive antibody are strongly indicative of WNV infections. Overall, 216 serum specimens reacted by PRNT test against AKR1C3-IN-1 SLEV, WNV or both at titers 20. Sixty-eight serum samples remain unidentified. The large number of unidentified flavivirus-positive samples detected by PRNT, ELISA, or both (148/474) could be due to 1) false positives; 2) cross-reactions between WNV- Serpine1 and SLEV-reactive antibodies that prevented definitive diagnosis by PRNT; 3) cross-reactive antibody and AKR1C3-IN-1 multiple, heterologous flavivirus infections; 4) previous infections by both WNV and SLEV; and/or 5) presence of other flaviviruses circulating in Argentina. SLEV is endemic throughout Argentina and, like WNV, belongs to the Japanese encephalitis virus serocomplex. Hemagglutination-inhibiting antibodies against several Brazilian AKR1C3-IN-1 flaviviruses (e.g., Bussuquara, Ilheus, Rocio viruses) have been reported in the neotropical region of extreme northern Argentina ( em 7 /em ), but these viruses have not been isolated in Argentina. Our serologic data suggest that WNV has established itself in 4 ecologic regions in Argentina in a brief period. Additional studies are AKR1C3-IN-1 needed to define the reservoir hosts and vectors of WNV in Argentina, and most importantly, to define the public health risk this virus represents. Acknowledgments We thank J. Rosa, A. Boris, R. Reynoso, C. Castillo, A. Zarco, N. AKR1C3-IN-1 Villafa?e, S. Flores, M.A. Cortez, M.E. Alvarez, J.R. Torres-Dowdall, D. Serra, and E. Edwards. We also thank the Cordoba Environment Agency (Cordoba Province), Department of Wildlife (Chaco Province), Municipality of San Miguel de Tucumn City (Tucumn Province), and SENASA for permission to obtain and export bird samples. This study was supported by grants from Agemcoa Macopma; de Promocin Cientifica y Tcnolgica C Fondo Nacional de Ciencia y Tecnologa (ANPCYTCFONCYT 01-12572 and 38060), Concejo Nacional de Investigaciones Cientifcas y Tecnolgicas (CONICET), Roemmers Foundation, Secretara de Ciencia y Tcnica C Universidad Nacional de Crdoba (SECYTCUNC), Secretara Nacional de Ciencia y Tcnica C Universidad Nacional del Noreste (SECYTCUNNE), Centers for Disease Control and Prevention C Division of Vector-Borne Infectious Diseases (CDCCDVBID), International Society for Infectious Diseases, International Union of Microbiological Societies C Society for General Microbiology (UNESCOCIUMSCSGM), Ministry of Public Health of the Tucumn Province, and the Public Health Department of the School of Medicine, National University of Tucumn. Footnotes em Suggested citation for this article /em : Diaz LA, Komar N, Visintin A, Juri MJD, Stein M, Allende RL, et al. West Nile virus in birds, Argentina [letter]. Emerg Infect Dis [serial on the Internet]. 2008 Apr [ em date cited /em ]. Available from http://www.cdc.gov/EID/content/14/4/689.htm.