West Nile virus: epidemiology, transmission, and clinical manifestations

West Nile Virus

In the summer of 1999, an unusual thing occurred: West Nile Encephalitis came to New York City. This was unusual because the disease had previously been present in the Middle East and Africa, and sporadically present in Europe, but unknown in North America. Its sudden appearance in America sparked speculation that West Nile Virus was brought to America by terrorists as a form of biological warfare.

In spite of the speculation, there is actually no proof of how the West Nile Virus came to the United States. What is known about the West Nile Virus in the United States is that it developed from the same strand of the virus that infected people in Tel Aviv, Israel. However, despite being able to determine that the Israeli and American strains of the West Nile Virus developed from the same strain, scientists have been unable to determine which strain developed first. The fact that the Israeli and American strains of West Nile Virus have a similar origin does nothing to squelch the idea of biological warfare; Israel and America are both popular targets for the same terrorist organizations, therefore it would not be uncommon for both locations to be the targets for similar biological attacks.

Furthermore, those who argue in favor of the idea that the West Nile Virus was introduced to America by terrorists point to the fact that it first appeared in America in New York City. Because the West Nile Virus is transmitted by mosquitoes, it appears counter-intuitive that it would make its first appearance in America in New York, rather than in one of the more humid, semi-tropical states. However, anyone who has spent a summer in the New York City region quickly becomes aware that mosquitoes are a tremendous problem during the summer in lower New York and New Jersey.

In addiction, the fact that similar strains of the West Nile Virus appeared in both Israel and America, and that West Nile is not enough to establish that American West Nile Virus was introduced by terrorists. In fact, that West Nile Virus first appeared in New York City has a harmless explanation as well. New York City continues to be a gateway for travelers coming into or leaving the United States. Israel is a popular destination from New York City; flights leave the three major New York City airports daily for Tel Aviv. Furthermore, New York and Newark both have active ports, where ships carrying goods from Israel dock. It does not require a stretch of the imagination to consider the fact that the West Nile Virus outbreak in America in 1999 was caused by the accidental transport of infected mosquitoes from Israel.

In support of the idea that the West Nile Virus was accidentally introduced to America by mosquitoes brought over from Israel is the fact that, in the summer of 1999, there were also two cases of malaria in New York City. Like West Nile Virus, malaria is a disease that is primarily transmitted by mosquitoes. Like West Nile Virus, one would expect malaria to occur in semi-tropical regions that traditionally have had malaria outbreaks. In the United States, those regions are generally confined to the southern half of the country. However, as previously indicated, the same conditions that promote mosquito growth in the South exist in the summer in New York City. In addition, most cases of malaria in America occur from travelers who have gone to infected regions without taking the proper precautions. There is no evidence that there was any link between the cases of malaria and West Nile Virus that occurred in New York City in 1999.

Furthermore, there is a final reason that argues against the idea that West Nile Virus was