[Concomitant activity of 2 bunyaviruses in horses in Argentina]

A serologic survey of horses for Kairi (KRI) and Cache Valley (CV), two related Bunyaviruses, was conducted simultaneously in Cordoba and Santa Fe provinces, Argentina, during late 1983 and 1984. The prevalence of neutralizing antibodies only for KRI was 13.3% and only for CV was 40.0%; but if the total positive sera for KRI and CV were taken into account, the prevalence reached 48.3 and 75.0%, respectively. The prevalence for CV was higher than for KRI in Cordoba (p less than 0.01), but both were similar in Santa Fe province. The demonstration of seroconversion in horses of the two zones for both viruses indicates that these viruses have a concomitant activity. The infection rates (number of infections per 100 horses-month) were very high in Cordoba (4.4 and 7.1 for KRI and CV) but also in Santa Fe (2.9 and 9.5 for the two viruses respectively), without significant difference in each province. Despite this high activity, no signs of illness or death imputed to these viruses were registered, in these areas during the period of observation. This apparent absence of associated equine disease may be the consequence of the low or null virus pathogenicity or the underrecognition or underreporting of the clinical cases.