Walfrido Kühl Svoboda[1], Lívia Carício Martins[2], Luciano de Souza Malanski[3], Marcos Massaaki Shiozawa[4], Kledir Anderson Hofstaetter Spohr[5], Carmen Lúcia Scortecci Hilst[6], Lucas M. Aguiar[7], Gabriela Ludwig[8], Fernando de Camargo Passos[9], Lineu Roberto da Silva[10], Selwyn Arlington Headley[11] and Italmar Teodorico Navarro[11] |
ABSTRACT Introduction: Saint Louis encephalitis virus (SLEV) primarily occurs in the Americas and produces disease predominantly in humans. This study investigated the serological presence of SLEV in nonhuman primates and horses from southern Brazil. Methods: From June 2004 to December 2005, sera from 133 monkeys (Alouatta caraya, n=43; Sapajus nigritus, n=64; Sapajus cay, n=26) trap-captured at the Paraná River basin region and 23 blood samples from farm horses were obtained and used for the serological detection of a panel of 19 arboviruses. All samples were analyzed in a hemagglutination inhibition (HI) assay; positive monkey samples were confi rmed in a mouse neutralization test (MNT). Additionally, all blood samples were inoculated into C6/36 cell culture for viral isolation. Results: Positive seroreactivity was only observed for SLEV. A prevalence of SLEV antibodies in sera was detected in Alouatta caraya (11.6%; 5/43), Sapajus nigritus (12.5%; 8/64), and S. cay (30.8%; 8/26) monkeys with the HI assay. Of the monkeys, 2.3% (1/42) of A. caraya, 6.3% 94/64) of S. nigritus, and 15.4% (4/26) of S. cay were positive for SLEV in the MNT. Additionally, SLEV antibodies were detected by HI in 39.1% (9/23) of the horses evaluated in this study. Arboviruses were not isolated from any blood sample. Conclusions: These results confi rmed the presence of SLEV in nonhuman primates and horses from southern Brazil. These fi ndings most likely represent the fi rst detection of this virus in nonhuman primates beyond the Amazon region. The detection of SLEV in animals within a geographical region distant from the Amazon basin suggests that there may be widespread and undiagnosed dissemination of this disease in Brazil. Keywords: Saint Louis encephalitis. Serology. New World monkeys. Horses. Arboviruses. |