West Nile Virus Prevention

woman applying mosquito repellent

West Nile Virus (WNV) is an illness carried by mosquitoes and passed on to people. It’s most common from June through September and can make people sick with flu-like symptoms and even lead to death in some cases. Everyone needs to be aware of mosquitoes and keep them away.

Protect Yourself

To keep yourself and your loved ones safe:

  • Wear long sleeves and pants when mosquitoes are most active: dawn and dusk.
  • Wear insect repellent when you head outdoors. Look for repellents that contain DEET, which will provide longer-lasting protection.
  • Empty standing water from household items like gutters, buckets and flower pots.
  • Repair any damaged screens you have on doors or windows.
  • Use air conditioning if you have it.

Reading the FAQs below can also be helpful.


What can you do if you find a dead bird?

To help the California Department of Health detect the spread of WNV, report dead birds at www.westnile.ca.gov or 1-877-WNV-BIRD (1-877-968-2473). This helps officials determine where more mosquito control is needed since mosquitoes acquire the virus from birds.

If someone does not get back to you within 24 hours, dispose of the bird, but do not handle it with your bare hands. There is no evidence West Nile is acquired by handling dead birds. However, it’s best to use a shovel to put the bird in a plastic bag, put the bag in the trash and wash your hands.

How is the virus transmitted?

WNV is transmitted to humans and animals through mosquito bites. Mosquitoes become infected when they bite and feed on infected birds.

In a small number of cases, West Nile has been spread through blood transfusions and organ transplants. It has also spread from mothers to their babies during pregnancy or delivery, or through breastfeeding, according to Butte County Public Health (BCPH).

What can happen if you become infected?

Most people show no symptoms. About 80% of individuals will not experience any illness, according to BCPH.

Some show mild symptoms. About 20% will have mild symptoms, such as:

  • Fever
  • Headache
  • Body aches
  • Nausea or vomiting
  • Swollen lymph glands or a skin rash on their chest, stomach, or back

Symptoms can last a few days, though even healthy people have been sick for several weeks.

A few have serious symptoms. Less than 1% of people (about 1 in 150) develop serious symptoms, according to BCPH. The elderly and individuals with weakened immune systems are particularly susceptible. These symptoms can include:

  • High fever
  • Headache
  • Neck stiffness
  • Stupor or disorientation
  • Coma
  • Tremors or convulsions
  • Muscle weakness
  • Loss of vision
  • Numbness
  • Paralysis

These symptoms may last several weeks, and neurological effects may be permanent.

How soon do infected people get sick?

If people develop symptoms, it typically happens between three and 14 days after they are bitten by the infected mosquito, according to BCPH.

How is WNV treated?

There is no specific treatment for West Nile. Milder symptoms pass on their own. In more severe cases, people usually need to go to the hospital, where they can receive supportive treatment. This includes intravenous fluids, help with breathing and nursing care.

Is there a vaccination against the virus?

There is no vaccine to prevent WNV in humans. However, there is a vaccine for horses.

Want to learn more?

For recorded information on West Nile, call the Enloe West Nile Virus Hotline at 530-332-7017 or refer to these resources:

Local Mosquito & Vector Control District Offices:

  • Butte County Mosquito & Vector Control: 530-533-6038 or www.bcmvcd.com
  • Durham Mosquito Abatement District: 530-345-2875 or durhammad.com
  • Oroville Mosquito Abatement District: 530-534-8383

Horse Owners:

For more information, call your local veterinarian or visit www.cdfa.ca.gov/ahfss/Animal_Health/WNV_Info.html.

Call the Hotline

For recorded information on West Nile, call the Enloe West Nile Virus Hotline at 530-332-7017.