Mosquito Season Approaching - Tips To Prepare For It

Armen Hareyan's picture

Mosquito season is approaching and public health officials want to remind residents that mosquitoes can transmit a number of diseases, including West Nile Virus.

In 2006, the first year for WNV in Oregon, Clackamas County had no cases, Multnomah County had five positive birds, and Washington County had one positive bird. Clark County Washington had one human case.

The spread of West Nile virus is unpredictable; however, trends throughout the country have shown a significant increase of cases in the second year of the virus. The following is an overview of West Nile Virus along with some prevention tips.

What is West Nile Virus?

West Nile Virus is carried by infected mosquitoes. It can cause serious illness in some people and horses. Mosquitoes become infected when they feed on infected birds of the Corvid family, such as ravens, crows, jays and magpies. The mosquito can then transmit the infection to humans and animals by biting them. You cannot get the virus from another person or animal.


Most people who become infected with the West Nile Virus do not become ill. Only about 20 percent develop West Nile fever, which features fever, headache, body aches, and occasionally a rash on the trunk of the body and swollen lymph glands. Symptoms begin 3-14 days after the bite of an infected mosquito and in cases of mild disease last a few days. People with questions about WNV symptoms should call their health care provider.

Only about one out of 150 of those who become infected develops a severe infection known as West Nile encephalitis or meningitis. Symptoms of a severe infection can include headache, high fever, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness and paralysis. Symptoms of severe disease may last several weeks, although some brain and nerve damage may be permanent. There is no effective treatment for WNV infection other than supportive medical care.

There are no vaccinations for humans, but vaccinations are available for horses. Horse owners should contact their veterinarians for more information.


There are two basic prevention strategies: reducing the mosquito population and avoiding mosquito bites. The best way to reduce the mosquito population is to drain sources of standing water beginning in early April. This will prevent mosquitoes from laying eggs and breeding.