Health

West Nile virus confirmed in mosquitoes and safety tips

From the Harris County Public Health and Environmental Services Office

May 29, 2006

HOUSTON — Harris County Public Health and Environmental Services Mosquito Control Division has confirmed that eleven (11) mosquito samples have tested positive for West Nile virus. The majority of positive samples were of the primary carrier of West Nile virus in Harris County, Culex quinquefasciatus. The Culex mosquito, also known as the Southern House mosquito, is most active from dusk to dawn.

The positive samples were collected from mosquito trapping sites in the following zip codes: 77004, 77013, 77016, 77028, 77050, 77077, 77345, 77506, 77536, and 77571.

These are the first locations this season that mosquitoes have tested positive for West Nile virus. Last year, the virus made its first appearance in mosquitoes in early May.

In response to WN virus being confirmed in mosquitoes, the evening spray operation has been activated in the affected and surrounding areas. Evening spray operations will occur Sunday – Thursday beginning at dusk.

HCPHES Mosquito Control has also expanded existing mosquito surveillance to facilitate earlier recognition and detection of disease carrying mosquitoes.

Because West Nile virus is now part of our environment, residents are strongly encouraged to help control mosquitoes and prevent disease by routinely following preventive measures to help reduce the likelihood of exposure to mosquitoes.

1. Don’t feed the storm drains. Sweep up lawn clippings, leaves and tree limbs from sidewalks and driveways.

2. Remove/empty any containers which may hold water. Flowerpots, tires, children’s toys, etc. should be drained, inverted, covered or removed. Change water in birdbaths at least once a week.

3. Keep rain gutters properly clean and draining and repair household leaks.

4. Make sure screens on windows and doors are in good condition.

5. Wear long pants and long sleeved shirts when outdoors particularly at dawn and dusk.

6. When outdoors, use an insect repellent containing the chemical compound DEET and apply as directed on the label. The Centers for Disease Control and Prevention (CDC) recommends using a repellent with a lower concentration of DEET, 10% or less, on children aged 2-12. Do not allow young children to apply repellent to themselves; have an adult do it for them.

7. When mosquitoes are noticed in your yard, spray with an outdoor mosquito spray. Be sure to use according to directions on the label. To control mosquitoes in your house, use a “flying insect spray”. Be sure to use according to directions on the label.

West Nile virus is a mosquito-borne disease that can cause encephalitis, a brain infection. Mosquitoes acquire WN virus from birds and pass it on to other birds, animals and people.

Most people who are infected with WN virus show no symptoms or only mild symptoms such as low-grade fever and headache. More severe signs and symptoms can include: high fever, stiff neck, muscle weakness, disorientation, brain inflammation (encephalitis), coma and rarely, death. When symptoms of infection do occur, they usually appear 5-15 days from the time a person was bitten.

For more information about West Nile virus, log on to www.harriscountyhealth.com or www.cdc.gov.

Image Source: Public Health Image Library at the Communicable Disease Center in Atlanta, GA.

"Culex quinquefasciatus mosquito on a human finger" image provided by CDC/William Brogdon.

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