Orthobunyavirus Antibodies in Humans, Yucatan Peninsula, Mexico

Bradley J. Blitvich

, Rungrat Saiyasombat, Lourdes G. Talavera-Aguilar, Julian E. Garcia-Rejon, Jose A. Farfan-Ale, Carlos Machain-Williams, and Maria A. Loroño-Pino

Author affiliations: Iowa State University College of Veterinary Medicine, Ames, Iowa, USA (B.J. Blitvich, R Saiyasombat); and Universidad Autónoma de Yucatán Centro de Investigaciones Regionales Dr. Hideyo Noguchi, Mérida, México (L.G. Talavera-Aguilar, J.E. Garcia-Rejon, J.A. Farfan-Ale, C. Machain-Williams, M.A. Loroño-Pino)

Abstract

We performed a serologic investigation to determine whether orthobunyaviruses commonly infect humans in the Yucatan Peninsula of Mexico. Orthobunyavirus-specific antibodies were detected by plaque reduction neutralization test in 146 (18%) of 823 persons tested. Further studies are needed to determine health risks for humans from this potentially deadly group of viruses.

We previously reported the isolation of Cache Valley virus (CVV), Kairi virus (KRIV), Cholul virus (CHLV), and South River virus (SOURV) from mosquitoes in the Yucatan Peninsula of Mexico (1–3). Antibodies to CVV, CHLV, and SOURV were also detected in livestock in this region (4). These viruses belong to the genus Orthobunyavirus (5). All viruses in this genus possess a tripartite, single-stranded, negative-sense RNA genome.
CVV is a recognized human pathogen (5) that has been linked to severe encephalitis and multiorgan failure. KRIV has not been implicated as a cause of human disease, although antibodies to this virus have been detected in humans in Argentina (6). Recent data suggest that CHLV is a reassortant that acquired its small RNA segment from CVV and medium and large RNA segments from Potosi virus (POTV) (1). No clear evidence exists for human susceptibility to infection with CHLV or SOURV. However, diagnostic laboratories rarely test for orthobunyavirus infection; therefore, the true disease incidence and seroprevalence of these viruses remains to be determined. Because orthobunyaviruses comprise a neglected but potentially deadly group of viruses and recent studies have provided evidence of orthobunyavirus activity in the Yucatan Peninsula (1–4), we investigated whether orthobunyaviruses commonly infect humans in this region.