Media Release

Mosquito season approaching - Tips to prepare for it 

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

 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.

Prevention

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.

-  At least once or twice per week, empty water from flowerpots, pet food and water dishes, birdbaths, swimming pool covers, buckets, barrels and cans.

- Check for clogged rain gutters and clean them out.

- Remove discarded tires, and items such as cans, bottles and other containers that could collect water.

- Be sure to check for containers or trash in places that may be hard to see, such as under bushes or under your home.

- Check around faucets and air conditioner units and repair leaks and eliminate puddles that remain for several days.

- Cover boats or store upside down or in a dry place.

- When swimming season is over, empty and store wading pools in a dry place. Cover large pools and check frequently to ensure against mosquito breeding. Ordinary concentrations of pool chemicals will not kill mosquito larvae. Keep pool water circulating and run filters April through October.

- Gambusia affinis (mosquito larvae eating fish) can be placed in closed system ponds. In Oregon, call your local county vector control for more information. This is a free service, but supplies are limited.

- Consider staying indoors at dawn, dusk and in early evening, which are peak mosquito biting times.

- When possible, wear long-sleeved shirts and long pants outdoors.

- Place mosquito netting over infant carriers.

- Install or repair window and door screens.

- Apply insect repellent containing DEET (N, N-diethyl-meta-toluamide) when you?re outdoors. Be sure to read and follow the manufacturer?s directions for use as printed on the product. Alternatively, spray clothing with DEET since mosquitoes may bite through thin clothing. If you spray your clothing, there is no need to spray repellent containing DEET on the skin under your clothing.

- Repellents may irritate the eyes and mouth, so avoid applying repellent to the hands of children. Read the manufacturer?s instructions thoroughly when applying to children.

Other insect repellents include:

*Picaridin (KBR 3023) and

*Oil of lemon eucalyptus [active ingredient: p-menthane 3,8-diol (PMD)], a plant- based repellent, is also registered with the EPA. In two recent scientific publications, when oil of lemon eucalyptus was tested against mosquitoes found in the United States, it provided protection similar to repellents with low concentrations of DEET. This information is provided by the Centers for Disease Control and Prevention.

Dead Corvid birds, such as crows, jays or magpies in an area may indicate that WNV is circulating between the birds and the mosquitoes in that area. The public can play an important role in helping to monitor for WNV. Persons that want to report a dead Corvid can call their local county vector control.

Clackamas County Vector Control: 503-655-8394, www.co.clackamas.or.us/vector/

Clark County Mosquito Control District: 360-397-8430, http://www.clark.wa.gov/mosquito/index.html

Multnomah County Vector Control: 503-988-3464 or 503-988-NILE, www.mchealth.org/vector/wnv.html

Washington County Environmental Health: 503-846-8722, http://www.co.washington.or.us/deptmts/hhs/env_hlth/vector/msqt_idx.htm

Centers for Disease Control and Prevention (CDC): www.cdc.gov/ncidod/dvbid/westnile/index.htm