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(WNV; genus Flavivirus; family Flaviviridae) has been perpetuating in North America since 1999 (1). However, its status as a self-perpetuating pathogen in South America remains uncertain. Infected horses and birds have been reported in various Caribbean Islands, Mexico, and northern Central America (2, 3). In South America, isolated reports of infected dead-end hosts (horses) have come from northern Colombia and Argentina, but they lack evidence for infection in avian amplifying hosts (4, 5). We report serologic evidence of establishment of WNV in South America.

Serum samples from birds and horses from 33 locations in Venezuela (Online Appendix Table, available from http://www. cdc. gov/EID/content/13/4/651-appT. htm) were screened for immunoglobulin G (IgG) antibodies against WNV antigen by ELISA (6) and confirmed by plaque reduction neutralization test (PRNT) as previously described (7). The …