While this contention is supported by many environmentalists and entomologists, the use of the chemical has spawned debate in the past. Currently, New York City is continuing with the use of pesticides in order to curb the mosquito population. Federal officials are also undertaking genetic decoding of the virus in order to provide a final and absolute confirmation of it as the West Nile strain. Epidemiologists and public health experts are exploring how the migratory patterns of birds might affect the spread of the disease. At the same time, researchers are unsure of how West Nile virus initially made its way into the United States.
Theories range from pinpointing bird smuggling, to an infected individual entering the country.
There is also the possibility that West Nile virus has been present in North America for some time but has gone undetected. International migration and tourism are key components to the spread of this and many other viral agents. As global air travel reaches ever higher levels, the ease with which diseases cross formerly formidable natural barriers is much greater. Moreover, the flow of people in and out of ports makes it more difficult to track and contain viral agents. Currently there is another outbreak of West Nile virus in Russia, another region of the world where the disease has never before been detected.