1995 epizootic of vesicular stomatitis (New Jersey serotype) in the western United States: An entomologic perspective

Entomologic and epizootic data are reviewed concerning the potential for tr ansmission of vesicular stomatitis (VS) virus by insects, including field d ata from case-positive premises in New Mexico and Colorado during the 1995 outbreak of the New Jersey serotype (VSNJ). As with previous outbreaks of V SNJ in the western United States, the 1995 epizootic illustrated that risk of exposure is seasonal, increasing during warm weather and decreasing with onset of cool weather; virus activity spread from south to north along riv er valleys of the southwestern and Rocky Mountain states; clinical disease was detected most commonly in horses, but also occurred in cattle and 1 Ila ma; and most infections were subclinical. Overall, 367 case-positive premis es were identified during the 1995 outbreak, with foci of virus activity al ong the Rio Grande River south of Albuquerque, NM, in southwestern Colorado , and along the Colorado River near Grand Junction, CO. The establishment o f a 16-km (10-mile) radius zone of restricted animal movement around confir med positive premises, along with imposition of state and international emb argoes, created economic hardship for livestock owners and producers. The i mportance of defining the role of blood-feeding insects as biological vecto rs of VSNJ virus relative to risk factors that promote high levels of insec t transmission, such as the presence of livestock along western river valle ys, blood feeding activity, and frequent transport of animals for recreatio nal purposes, is emphasized as a basis for developing effective disease man agement.