West Nile virus in the Grand Valley has followed a predictable pattern. The virus likely entered the valley with a wild host such as magpies, crows or ravens and was then passed on to humans through mosquito bites. The virus remained at low levels until the first major outbreak when the number of human and avian cases increased dramatically. After the initial outbreak, the virus has remained in the host populations at low levels. When conditions become favorable another outbreak occurs, but usually not as severe as the initial one. Over time the virus oscillates between the outbreak and remission stages. This is epidemiology 101.
No matter how well intentioned, attempts to control West Nile by controlling its vectors (mosquitoes) have largely been a public relations campaign. It cannot be shown that dumping biocides into the environment to control mosquitoes has prevented a single human case of the disease. Like other arthropod-borne encephalitides, West Nile is here to stay. The best defense against West Nile is, and always will be, personal protection (repellents, clothing, behavior).
The local bureaucracy that has been put in place to control West Nile's vectors is now attempting to expand its tax base. Although it is a good idea to control mosquitoes, and it is certainly a tragedy to anyone affected by the disease, throwing more tax dollars at the problem in order to decrease the incidence of West Nile is dubious.
Letter writer, A. Gamble, has questioned recent attempts to increase funding to the Grand Valley Mosquito Control District by raising property taxes (letters to the editor, FP, 28 Sept. 2012). Increasing funding also should be questioned on the grounds of the biology of epidemics. Irrational fear that doing something might be better than doing nothing is simply that.
John Jenkins, Ph.D.