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News from Wyoming Department of Health

West Nile Virus Spread by Mosquitoes Remains a Threat


West Nile virus (WNV) spread by mosquitoes remains a potential threat in Wyoming as warmer weather arrives across the state, says the Wyoming Department of Health.

“West Nile virus can sometimes cause serious illness,” said Emily Thorp, surveillance epidemiologist with the Wyoming Department of Health. “Because mosquitoes spread the virus by feeding on infected birds and then biting people, other birds and animals, preventing mosquito breeding and avoiding bites are important.”

Last year was an active WNV season in several states. Texas was particularly hard hit with 844 reported human cases and 89 deaths. In Wyoming last year, seven human WNV cases were reported. Since WNV first appeared in Wyoming in 2002, the annual numbers of reported human cases have ranged from two with no deaths to 393 and nine deaths.

Thorp recommended the “5 D’s” of prevention:

1) DAWN and 2) DUSK - Most mosquito species prefer to feed at dawn or dusk, so avoid spending time outside during these times.
3) DRESS - Wear shoes, socks, long pants and a long-sleeved shirt outdoors or when mosquitoes are most active. Clothing should be light-colored and made of tightly woven materials.
4) DRAIN - Mosquitoes breed in shallow, stagnant water. Reduce the amount of standing water by draining and/or removing it.
5) DEET - Use an insect repellent containing DEET (N, N-diethyl-m-toluamide). When using DEET, be sure to read and follow the label instructions. Other insect repellents such as Picaridin (KBR 3023) or oil of lemon eucalyptus can also be effective.

Steps recommended for property owners to reduce mosquito breeding grounds:

• Use smart landscaping to eliminate standing water.
• Repair failed septic tanks.
• Dispose of containers that collect water such as tin cans, ceramic pots or plastic containers.
• Remove or discard old tires.
• If you cannot dispose of old tires, drill holes to allow water to drain.
• For containers such as bird baths or troughs, replace water at least once a week.
• Repair leaky water pipes and outdoor faucets.
• Ensure roof gutters drain properly.
• Turn over plastic wading pools and wheelbarrows when not in use.
• Cover trash containers.
• Aerate ornamental ponds or stock with predatory fish.
• Clean and chlorinate outdoor swimming pools even when not in use.
• Keep drains, ditches and culverts free of grass clippings, weeds, and trash.
• Remove vegetation and debris from ornamental pond edges.

Thorp noted West Nile virus activity in any given year is tough to predict The state has seen human cases of WNV reported as early as May and as late as October with late summer and early fall as the typical peak times.

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