MercoPress. South Atlantic News Agency

Two cases of West Nile virus reported in Argentina

Two cases of West Nile virus in horses have been detected in Argentina whose authorities have reported them to the Paris based Epizooties International Office and following international procedure, have banned all live horse exports.

Although Argentine sanitary authorities have yet to release further details the Buenos Aires press reports that the two animals involved are racing horses belong to a farm 145 kilometres from Argentina's capital.

West Nile virus (WNV) is a potentially serious illness, which was first detected in North America in 1999 and has since rapidly expanded. Most often, WNV is spread by the bite of an infected mosquito and mosquitoes become infected when they feed on infected birds. Infected mosquitoes can then spread WNV to humans and other animals such as in this case horses.

Most infections in humans, 80%, don't show symptoms but for the remaining 20% fever, head aches, nausea, vomiting and other conditions similar to those of a strong flu are common. Data indicates that only one in 150 humans infected with WNV can develop a serious case of encephalitis or meningitis.

WMV belongs to the flavivirus family and there are no vaccines so preventive measures are recommended.

In the areas with reported cases mosquito nets at home, repellents when outdoors and protective gear such as gloves and glasses are recommended particularly for farm labourers.

Doctor Tomas Orduna head of the Regional Pathologies Unit and Tropical Medicine from Buenos Aires Hospital Muñiz points out that "it's quite surprising that two mammals are the first cases reported in Argentina and not birds. Horses are WNV sentinels for humans but birds are the main reservoir".

"If the virus is in mosquitoes we must conclude that birds are infected and the fact that this has not been detected is alarming, particularly when bird migration is South to North".

Mario Lopez Oliva, president of the Argentine Association of Equine Veterinary Medicine said the virus first arrived in America, in the United States in 1999 with exotic birds' imports, forcing to close Central Park in New York. "It was only a question of time for the WNV to arrive in Argentina".

The WNV disease was first detected in an African woman in Uganda along the Nile in 1937. The natural hosts are birds and mosquitoes transmit it to mammals that are the end host and therefore do not transmit WNV. In the US between 1999 and 2001, 149 human infections were detected with 18 deaths. In 2002 and 2003 the number jumped to 14.000 cases and 500 deaths.

"The bad news is that WNV has arrived in Argentina; the good news is that it's winter and mosquitoes are over, which gives us time for a prevention and information campaign", underlined Dr. Lopez Oliva.