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Equine Encephalitis in Argentina

Several equine viral agents with potential for human infection have been reported in Argentina.. The following background information is abstracted from Gideon and the Gideon e-book series. [1,2]

A. Eastern equine encephalitis:
Seropositivity toward eastern equine encephalitis virus was demonstrated in wild and domestic birds, wild mammals, and horses during 1977 to 1980.
– The principal mosquito vector is Aedes (Ochlerotatus) taeniorhynchus.
– Additional vectors include Culex nigripalpus, C. caudelli, C. spissipes and C. taeniopus.
– Eastern equine encephalitis has been reported from Buenos Aires.

Notable outbreaks:
1981 – An outbreak if eastern equine encephalitis was reported among equines in Santiago del Estero Province.

B. Western equine encephalitis:
An epizootic was reported during 1982 to 1983, with continued cases to 1986.
– Ochlerotatus (Aedes) albifasciatus is the presumed vector in Argentina.
– During the epidemic of 1982 to 1983, WEE virus was also demonstrated in Anopheles albitarsis, Mansonia species and Psorophora pallescens.

C. Venezuelan equine encephalitis
Complement-fixing antibodies toward Venezuelan equine encephalitis virus have been demonstrated among humans in Corrientes and Chaco (1983 publication)
– Related agents, Pixuna and Rio Negro viruses, have been identified among rodents in Tucuman Province.

Seroprevalence surveys:
51.6% of persons on General Belgrano Island, Formosa Province (NT, 1993 publication)
30% to 70% of persons on General Belgrano Island, Formosa Province (NT, 2003 publication)

A. Calchaqui virus:
Seropositivity of humans and horses toward Calchaqui virus has been demonstrated in Santa Fe Province. Calchaqui virus has also been identified in a local mosquito.

B. Rabies (an extensive note regarding rabies in Argentina is available on request)

C. Vesicular stomatitis virus infection has been reported among animals in Argentina (2011 publication)

A. Cache Valley, Kairi and Bunyamwera viruses:
Seroprevalence surveys:
5.7% of human sera in Cordoba are seropositive toward Cache Valley virus and 5.92% toward Kairi virus (2004 to 2005)
13.3% of horses in Santa Fe and Cordoba are seropositive toward Kairi virus , and 40% toward Cache Valley virus (1983 to 1984)
6.6% of free-ranging birds in Cordoba City were seropositive toward Bunyamwera virus in 2004, 13.8% in 2005

A. West Nile fever virus:
West Nile fever virus was detected for the first time in Argentina in 2006 – two horses in San Antonio de Areco and one in San Isidro, Buenos Aires Province.
– Infection was documented in free-ranging birds during 2005 to 2006.
– The country’s first cases of human infection were reported in 2006 – one case in the city of Marcos Juarez in Cordoba Province and 3 additional cases in Chaco province.

1. Berger SA. Infectious Diseases of Argentina, 2011. 417 pp, 96 graphs, 1516 references. Gideon e-books,
2. Berger SA. Equine encephalitis: Global Status, 2011. 38 pp, 17 graphs, 282 references. Gideon e-books,

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