West Nile virus infection of birds, Mexico

Emerg Infect Dis. 2011 Dec;17(12):2245-52. doi: 10.3201/eid1712.110294.

Abstract

West Nile virus (WNV) has caused disease in humans, equids, and birds at lower frequency in Mexico than in the United States. We hypothesized that the seemingly reduced virulence in Mexico was caused by attenuation of the Tabasco strain from southeastern Mexico, resulting in lower viremia than that caused by the Tecate strain from the more northern location of Baja California. During 2006-2008, we tested this hypothesis in candidate avian amplifying hosts: domestic chickens, rock pigeons, house sparrows, great-tailed grackles, and clay-colored thrushes. Only great-tailed grackles and house sparrows were competent amplifying hosts for both strains, and deaths occurred in each species. Tecate strain viremia levels were higher for thrushes. Both strains produced low-level viremia in pigeons and chickens. Our results suggest that certain avian hosts within Mexico are competent for efficient amplification of both northern and southern WNV strains and that both strains likely contribute to bird deaths.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Bird Diseases / virology*
  • Birds / virology*
  • Communicable Diseases, Emerging / veterinary
  • Communicable Diseases, Emerging / virology
  • Disease Reservoirs / veterinary
  • Disease Reservoirs / virology
  • Humans
  • Mexico
  • Passeriformes / virology
  • Viremia / veterinary
  • Viremia / virology
  • Virulence
  • Virus Shedding
  • West Nile Fever / veterinary*
  • West Nile Fever / virology
  • West Nile virus / genetics
  • West Nile virus / immunology
  • West Nile virus / isolation & purification
  • West Nile virus / pathogenicity