The National Centers for Disease Control (CDC) says that 80% of people infected with West Nile Virus will not develop any illness or symptoms while 20% will have West Nile Fever. West Nile Fever is similar to the flu.
The CDC says that 1 in 150 persons will develop a more severe form of the disease and that people over age 50 and some immunocompromised persons (for example transplant patients) are at highest risk for getting severely ill when infected with West Nile Virus. In 2004 in California there were 779 West Nile Virus diagnosed cases, 289 were severe and there were 28 WNV-related deaths (CDC data). This figure dropped to 18 in 2005 and 7 in 2006. It is thought that once you are infected you will have lifelong immunity, much like chicken pox. To put the risk in perspective, out of a population of 35 million and at the rate of 1 severe case per 150 infections, there would have been roughly 43,350 total West Nile Virus infections last year, and the 289 severe cases would be 0.6% of the total. The chance of dying in California of West Nile Virus Infection in 2004 was 1 per 1,000,000. Whereas 55,340 Californians died of cancer in 2004 according to CDC, or about 1600 per 1,000,000.
Certain species of mosquito transmit West Nile Virus (WNV). The Sacramento Yolo Mosquito and Vector Control District began applying adulticides (pesticides to kill adult mosquitoes as opposed to larva) by aerial and ground spraying in the urban areas of Sacramento County in recent days. The District now plans to implement its adulticide spraying in urbanized areas of Yolo County including Davis and Woodland. The pesticide being used is Pyrenone 25-5.
We advocate a stop to the involuntary spraying of
adulticides in urban and residential areas. We support the Integrated Pest Management approach
that includes greater personal responsibility, public education and
larvicide efforts without spraying adulticides.
We believe the District should establish a community task force to
allow the public a true voice in decision making, as is recommended by
the CDC (see the CDC guidelines
for surveillance, prevention, and control, page 39), and that the
District should implement a reverse 911 phone system for citizen
notification. This would amount to spending public funds
rationally to protect public health based on facts and not fear.
See an excellent fact sheet from Beyond Pesticides about mosquitoes, pesticides, and the West Nile virus.