Mosquito Control Guide |
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| Mosquito Control | |
West Nile VirusOf all the diseases spread by mosquito bite, only two have received much attention in the popular press. One, justifiably, is malaria, which has exterminated more human beings over the course of our history than humans themselves. The other, far less justifiably, is West Nile virus. We say “far less justifiably” because the number of deaths resulting from West Nile is far lower. However, it would be a mistake to underestimate the severity of the virus or its possible effects. West Nile is a common flavivirus in Africa, West Asia, and the Middle East. A flavivirus is any of sixty-nine pathogens classified in the order Flaviviridae. The most common disease caused by flavivira is Yellow Fever. The Latin word for “yellow” is flavus, hence the name of these vira. Among the other flavivira are dengue fever (1, 2, 3 and 4), St. Louis encephalitis, Japanese encephalitis, Murray Valley or Kunjin Rocio encephalitis, tick-borne encephalitis, Kyasanur Forest disease, Omsk hemorrhagic fever, louping ill, powassan, and hepatitis C. Of these, West Nile is most similar to St. Louis encephalitis, cases of which predate West Nile in the U.S. West Nile virus may infect humans, mosquitoes, birds, horses, and certain other mammals. Until 1999, no cases of West Nile were reported in America; but at some point during or before that summer, doctors from the U.S. Centers for Disease Control believe the disease broke out in the eastern states, most likely New York. It was detected in “overwintering” (that is, surviving through winter) Culex mosquitoes in New York City in early 2000. A few months later, the widespread transmission of the disease proved its survival through cold conditions. Now the CDC believes the West Nile virus is “permanently established in the Western Hemisphere.” For a breakdown of cases by state as of 11 January 2005, see the map below. In warm tropical latitudes, West Nile can be transmitted year round. In the temperate zones (i.e., areas between 23.5 and 66.5 degrees, north and south), West Nile encephalitis cases occur mostly in last summer or early fall. West Nile encephalitis, an inflammation of the brain, is the most severe disease caused by the West Nile virus. Others include West Nile meningitis, an inflammation of the meninges (the membrane that surrounds and protects the brain and spinal cord), and West Nile meningoencephalitis, an inflammation of both the brain and meninges. It is these inflammatory ailments, rather than the initial infection, that can lead to deaths or serious health problems. The virus also causes West Nile Fever, which is characterized by headache, exhaustion, body aches, occasional rashes, and of course, high fever. Even healthy victims can become sick for several weeks, though the disease may last as little as a few days.
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Heartworm in Dogs |