Moves made to fight West Nile virus |

Moves made to fight West Nile virus

Thank you for your article regarding our West Nile virus (WNV) prevention presentation recently to the Nevada County Board of Supervisors.

I would like to take this opportunity to provide a little more information regarding WNV and to correct several inaccuracies in the article. The county has currently budgeted approximately $40,000 to conduct educational outreach, provide mosquito fish to county residents, and conduct minimal mosquito surveillance that will include monitoring two sentinel flocks of chickens. There are usually 10 chickens per flock, and these are used as a tool to detect mosquito-borne diseases. Although chickens do not acquire WNV, those bitten by infective mosquitoes will have an indication of the virus in their blood. Small blood samples are taken from the chickens every two weeks and checked for viruses, including WNV.

The article also states, “Last year, there was one case [of WNV illness] in Nevada County… Southern California was hit especially hard, with more than 300 positive human cases and 10 fatalities.” As stated in our presentation, there were 819 diagnosed cases of WNV illness and 25 fatalities in California. There were over 300 cases of human illness in Los Angeles County alone. Twenty-four of the fatalities were in Southern California. There have been no cases of WNV illness diagnosed and reported in Nevada County to date.

The virus has a “life cycle” that includes wild animals – primarily birds – and mosquitoes. There is no evidence that mosquitoes can transmit WNV from biting an infected human, and WNV is not contagious between people. When a mosquito bites a sick bird, the virus is passed on to the next “victim” that the mosquito bites. Some animals and birds show no effect from the virus. However, many wild birds rapidly die. These include crows, jays and magpies.

Testing dead birds for the virus is another early warning system employed by public health officials. California has a dead bird hotline and Web site for citizens to report dead birds. We encourage anyone finding a sick or recently dead bird (24 hours) to contact the hotline at either 1-800-WNV-BIRD or at

There currently is no vaccine against WNV and no specific treatment for the illness. Most people bitten by an infective mosquito will have no symptoms. A few will develop a flu-like illness. Less than 1 percent of those showing symptoms develop a more serious and life-threatening form of the disease. Although anyone bitten by an infective mosquito can become ill, those persons over the age of 50 or with ongoing medical conditions are more likely to develop serious symptoms. It is especially important for people in these groups to protect themselves from mosquito bites.

The best way to prevent the disease is to prevent mosquito bites. Eliminating mosquito breeding will significantly reduce the incidence of illness acquired by humans. The development of a mosquito abatement program in the county is a primary concern among public health officials.

Removing sources of mosquito breeding is something we can all do. Mosquitoes breed in standing water. They can go from egg to adult in as little as a week. While most of us think of ponds or marshes as the primary sources of mosquitoes, there can be many breeding areas in anyone’s yard or garden. Some examples include water standing in flowerpots, old tires, buckets, empty paint cans, tarps, children’s toys, mud puddles, even the cavities in oak trees. It is very important to do a survey of your property and drain standing water. Breaking the breeding cycle is one of the most effective prevention measures.

Personal protection is the other prevention measure. This includes:

Avoid outdoor activity during the times of highest mosquito activity – generally dusk to dawn.

Use a quality mosquito repellent when outdoors. Products containing DEET are the most effective in preventing mosquitoes from biting.

Wear long sleeves, long pants, and socks when possible outdoors. Since mosquitoes can bite through some clothing, applying DEET to the clothing is even more effective.

West Nile virus can cause serious illness and is a significant threat to public health. There is a very high likelihood that Northern California will experience a sharp increase in WNV activity this coming season. We greatly appreciate The Union publishing information to help make the citizens of Nevada County more aware of the disease and how to prevent it. For more information on WNV, please visit our WNV Web site at


Larry Sage is director of Nevada County’s Department of Environmental Health.

Support Local Journalism

Support Local Journalism

Readers around Grass Valley and Nevada County make The Union’s work possible. Your financial contribution supports our efforts to deliver quality, locally relevant journalism.

Now more than ever, your support is critical to help us keep our community informed about the evolving coronavirus pandemic and the impact it is having locally. Every contribution, however large or small, will make a difference.

Your donation will help us continue to cover COVID-19 and our other vital local news.


Start a dialogue, stay on topic and be civil.
If you don't follow the rules, your comment may be deleted.

User Legend: iconModerator iconTrusted User