RESUMEN
It is shown here the WEE virus activity in ARgentina in 1983-1986 post-epizootic period. A surveillance system was established by the equine case notification and the sentinel animal method. Among the thirteen equine focus notified between September 1983-September 1985 in Córdoba and Santa Fe Provinces, 5 presumptive cases out of 16 sick horses were confirmed by the hemagglutination inhibition test for WEE epizootic virus. Twenty eight notified human cases were studied with negative results. The neutralizing antibody (Ac NT) prevalence among sentinel horses in Córdoba Province (4
) was lower than that of Santa Fe Province (13
) in April, 1984. It was shown that Ac NT disappeared in a 12-month period in 40
of the Santa Fe horses. Two seroconversions in Córdoba (12/1983 to 4/1986) and 9 seroconversions in Santa Fe (2/1984 to 7/1986) were registered. One of the sentinel horses form Córdoba Province also seroconverted with the enzootic WEE AG 80-646 virus. Due to the recognized cross-antigenicity between both viruses, reactivity was attributed to WEE epizootic virus. No viral activity was detected in the domestic birds. With this contribution, the study of one epizootic cycle of WEE virus was completed: pre-epizootic silence (1977-1980), epizootic (1982-1983) and residual focus plus inapparent infections during a post-epizootic period (1983-1986).
RESUMEN
It is shown here the WEE virus activity in ARgentina in 1983-1986 post-epizootic period. A surveillance system was established by the equine case notification and the sentinel animal method. Among the thirteen equine focus notified between September 1983-September 1985 in Córdoba and Santa Fe Provinces, 5 presumptive cases out of 16 sick horses were confirmed by the hemagglutination inhibition test for WEE epizootic virus. Twenty eight notified human cases were studied with negative results. The neutralizing antibody (Ac NT) prevalence among sentinel horses in Córdoba Province (4
) was lower than that of Santa Fe Province (13
) in April, 1984. It was shown that Ac NT disappeared in a 12-month period in 40
of the Santa Fe horses. Two seroconversions in Córdoba (12/1983 to 4/1986) and 9 seroconversions in Santa Fe (2/1984 to 7/1986) were registered. One of the sentinel horses form Córdoba Province also seroconverted with the enzootic WEE AG 80-646 virus. Due to the recognized cross-antigenicity between both viruses, reactivity was attributed to WEE epizootic virus. No viral activity was detected in the domestic birds. With this contribution, the study of one epizootic cycle of WEE virus was completed: pre-epizootic silence (1977-1980), epizootic (1982-1983) and residual focus plus inapparent infections during a post-epizootic period (1983-1986).
RESUMEN
In 1981, a localized epizootic of Eastern Equine Encephalitis (EEE) occurred in irrigated areas of four counties in the province of Santiago del Estero, Argentina. The diagnosis was confirmed by serology, and there was no evidence of involvement of Western or Venezuelan equine encephalitis viruses. The overall incidence of equine encephalitis was estimated 17
, the case-fatality rate at 61
and the inapparent: apparent infection ratio less than or equal to 2.9:1. This is the first localized epizootic defined in Argentina and the first in which EEE has been found as the sole etiologic arbovirus. This posed the possibility to look for human infection in the area. In spite of a careful surveillance, no evidence of human disease or infection was found, differing from the situation in USA where EEE virus is a public health problem. Nevertheless vector/s and vertebrate hosts involved in the transmission cycle in Argentina remain unknown, precluding at present speculations on the potential human risk.