The West Nile arbovirus maintained in nature via a bird-mosquito-bird cycle. It is transmitted from birds to humans and other mammals by mosquitoes, generally from the Culex genus. Humans, the equine species and other mammals are the virus’ accidental hosts.

The West Nile virus made it first appearance in the hemisphere in the northeast of the United States in 1999, with an outbreak of 62 recorded cases and seven deaths. Since then it has spread to 34 states, advancing progressively toward the south of that country. It is now present in Florida, Texas, Louisiana, Mississippi and other areas, where the highest numbers of cases and deaths have occurred.

As is evident, the virus has come very close to neighboring Mexico, Central America and the Caribbean, obviously including our country. In our assessment, the fundamental risk lies in the fact that virus could be transmitted by the 100-plus different bird species migrating from the northern territory to the southern hemisphere.

Over 60 varieties of those birds cross different areas of Cuban territory and many remain on our island for close to six months, independently of the many that continue toward the Caribbean or South America, where they also spend long months waiting for low northern temperatures to rise before returning to their country of origin. It is precisely in the month of October that north-south bird migration begins.

The virus is transmitted from bird to bird and from birds to humans through the same vector, which in this case is not the Aedes Aegypti, a more domestic species, but varieties of the Culex species, which flourish in forests virtually everywhere.

Data on this virus, its effects and treatment are not well known. Our country has adopted measures such as vigilance and close observation of the presence of these birds, the level of infestation they could harbor, cases of human contagions if any are produced, and other pertinent measures.

All potential international information is being sought and the most appropriate steps to be taken in terms of prevention, recognition, diagnosis and treatment are being discussed.

The Cuban government is willing to cooperate to its fullest capacity with public health authorities in the United States and other countries in the hemisphere in terms of research and any efforts needed to confront this new threat to the health of the citizens of this hemisphere, already affected by AIDS, dengue and other plagues which are threatening and aggravating the complicated state of health of the majority of our peoples to a greater or lesser degree.

To date, no case of Nile fever has been detected in Cuba or any other Caribbean, Central or South American country. Nevertheless, in our judgment, it is essential to be warned and on the alert.