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All of the other sections of our West Nile virus site have recently been updated! Reportable news as of 6/15/05 has been incorporated into: The Virus, The Vectors, The Victims, Effects on Wildlife, and What You Can Do.

Current information on human cases and geographic occurrence

Because the situation changes continually, we will not attempt to post such data here. If you seek information on West Nile virus’s effects on humans, the Center for Disease Control and Prevention’s WNV site is a good place to start; for current cases, click on “Maps and Human Cases” on the left. If you seek information regarding geographic occurrence within the United States, the maps available at the United States Geological Survey’s WNV site depict the current distributions for: birds, humans, mosquitoes (where testing occurs), sentinel chickens (where they exist), and horses (the primary animal composing their category “veterinary”). Maps depicting WNV’s detection in the categories above for the years 1999-2003 are also available at the USGS site (click on “Historical Data”). Information on the occurrence in Canada is available on Health Canada’s WNV website.

WNV treatment trials underway; patients being recruited

A couple of trials designed to test the efficacy of possible WNV treatments are currently recruiting participants. Information on trial goals and patient eligibility can be found at the National Institute of Health’s ClinicalTrials.

Not So New, But Worth Keeping Up:

Our 2-page “The Basics” for display or distribution!

This downloadable document summarizes what you need to know, and the steps you can take, to reduce your chance of exposure to WNV.

Copepods – small crustaceans – control mosquitoes!

Microscopic crustaceans called copepods turn out to be extremely effective at controlling mosquitoes. These organisms are said to pose no threat to people or other animals and can survive year-round in any size body of fresh water, including the stagnant water in discarded tires and other containers. Copepods feed aggressively on larval mosquitoes and will even kill the larvae when not looking for food; the survivorship of mosquito larvae is reduced up to 100% in the presence of certain copepods. These crustaceans do not occur in all bodies of water and would have to be introduced to many mosquito breeding sites, but once established they reach numbers high enough for effective mosquito control. Researchers at the University of Florida’s Florida Medical Entomology Laboratory have been looking at a species with a worldwide distribution in subtropical areas (which can survive for months at 0^oC), and the government of Vietnam recently reported that introduction of copepods to water storage areas (in addition to eliminating discarded water containers) reduced both mosquito populations and Dengue fever cases¹. Additional success stories regarding the use of copepods for mosquito control can be found in reference #2, below.

More on dealing with mosquitoes

University of Florida researchers have identified a group of molecules that function to deliver needed amino acids to mosquito cells. The amino acid transporters appear to be unique to insects, and may be able to be exploited for mosquito control; interference with their function could deprive mosquitoes of necessary nutrients³.

British researchers have identified chemicals produced by human bodies that reduce attractiveness to mosquitoes. The researchers collected the chemicals on the bodies of people who were not attractive to mosquitoes and sprayed them on the bodies of people who were, and mosquitoes no longer found the latter attractive! The researchers are hoping to be able to produce a new natural mosquito repellent⁴.

Cats and dogs and WNV

Four cats and four dogs were experimentally exposed to the virus via mosquito bites, and four cats were fed infected mice. The four dogs developed viremias of low magnitude and short duration, but all eight cats developed viremias possibly capable of infecting mosquitoes⁵. That cats infected through eating infected prey might contribute to local transmission of WNV is all the more reason to KEEP YOUR CATS INDOORS.

References:

Updated 6/16/05