West Nile Virus -- Information and Links

How is West Nile Virus (WNV) transmitted?

WNV is essentially a bird disease with corvid species such as crows, ravens, magpies, and jays being those that are the most susceptible to dying. Two species of mosquitoes are carriers of WNV: Culex tarsalis and Culex pipiens. These mosquitoes are infected by feeding on a bird with the virus in its blood. The virus is transmitted to a new host when, during the few feeding hours around dusk and dawn, a female mosquito bites another person or animal. Mosquitoes are attracted to people primarily because of the carbon dioxide we exhale. One bite is all it can take to infect someone. Humans are incidental dead-end hosts in that they can’t infect other mosquitoes. These viruses are prevalent from May to September when mosquitoes are most abundant. The highest risk to people occurs primarily from August through early September.

What are the symptoms of West Nile Fever and Encephalitis?

Both diseases attack the nervous system. Symptoms of the more common fever syndrome include fever, headache and weakness. They can persist for 2-7 days.

The most serious manifestation of a West Nile virus infection is encephalitis (or brain inflammation). Symptoms for this include sudden fever and headache progressing to a stiff neck, disorientation and possible coma. This can be fatal.

What do we expect for this summer?

After mosquito eggs are laid, they’ll need about 7-10 days of warm weather and water temperatures to hatch.

It is difficult to estimate, but the Arkansas River Valley is endemic for West Nile virus activity and it is here to stay. It may be very prevalent or it could be mild.

What can we do to protect ourselves and reduce the transmission of WNV?

·         Limit time spent outdoors at dawn and dusk, when mosquitoes are most active

·         When you are outdoors:

·         Wear lightweight long-sleeved shirts and long pants

·         Spray your clothing with insect repellant containing DEET – generally, the higher the concentration, the longer the protection time.

·         Apply insect repellant sparingly to exposed skin when outside

§ Products with 10% or less DEET are recommended for children

§ Other CDC approved repellents such as picaridin and lemon of eucalyptus oil

·         At homes or in garages, install or repair window and door screens, insuring they are tight to keep mosquitoes out

·         Remove standing water where mosquitoes lay eggs – like old tires, empty cans, leaky air conditioners, clogged rain gutters, etc.

·         In the case of permanent ponds, stock them with fish that eat mosquito larvae like goldfish and fathead minnows.

What activities locally are going on to prevent more WNV cases?

As a part of our ongoing efforts, Southeast Environment Health will continue mosquito collection and population surveillance at established sites. We anticipate setting over 100 total trappings during the 2010 surveillance period. We participate in statewide WNV data collection and communication activities based on this surveillance. This helps provide knowledge of the abundance and type of mosquitoes, infection rates and the likeliness of WNV disease transmission. This information also aids in local mosquito population control and abatement activities.

Where can those interested get more information?

Southeastern Environmental Health has a variety of public information and educational materials available. Additionally, there is a toll-free Fight the Bite hotline established to answer questions on WNV 7 days a week and 24 hours a day. The number is 1-877-462-2911 and the website is www.fightthebitecolorado.com. You may also contact Prowers County Public Health/Southeast Environmental Health at 336-8721.