Scientists Begin 2002 Monitoring for West Nile Virus

Auburn, April 18, 2002---Wildlife biologists and other scientists are poised to begin a third year of monitoring Alabama's bird population for West Nile virus (WNV). In people, it can cause West Nile encephalitis, a potentially deadly inflammation of the brain. Last year, the state had its first two human cases of WNV. One person recovered, but a Jefferson County man died.

"The virus is spread by mosquitoes that get the disease from infected birds," says Ashley Rossi, who coordinates the West Nile surveillance team in Alabama. "Birds are the natural host for the virus, which can be fatal to birds, horses, humans and other mammals."

Rossi, who is a wildlife biologist with the U.S. Department of Agriculture's Wildlife Services program in Alabama, says testing of dead birds will be restricted to several species of birds including crows, blue jays and raptors. Raptors found in Alabama include hawks, eagles, ospreys and owls.

Rossi says the surveillance team needs the public's assistance with the monitoring effort.

"The public can help by identifying and, if possible, collecting dead birds for us to examine," says Rossi. "We will begin accepting dead birds for testing in May. We are limiting the species we're looking at because to date WNV has been identified more frequently in these species."

Nationally, more crows have tested positive for WNV. But in Alabama last year, 33 of the 59 WNV-positive birds were blue jays.

"This may be related solely to how we receive our samples of dead birds," says Rossi. "We received more samples from Jefferson and other urban counties. Homeowners and others in these areas are more likely to see jays than crows."

Rossi says the public should take some basic precautions in collecting the dead bird.

First, wear plastic gloves, or turn a large zipper-seal plastic bag inside out. Place your hand in the bag, and pick up the bird with your covered hand. Then, grasp the edges of the bag and pull so it encloses the bird. Seal the bag. Place the first bag in a second bag.

If possible, put the sealed bag in a cooler with ice. Then take the sample to your county Extension office.

"The county Extension offices know how to get in contact with us to arrange delivery of the sample," says Rossi. "When we receive the sample, our scientists will conduct necropsies to determine if West Nile virus is present."

In 2001, more than 770 dead birds were tested for WNV as a result of the monitoring program. That's almost three times the number tested in 2000.

In addition to monitoring the state's wild bird population for the disease, scientists are also collecting mosquito samples and examining them for the virus. In 2001, nearly 125,000 mosquitoes collected in 22 Alabama counties were tested for WNV. That's double the mosquito samples submitted for testing in 2000.

But scientists are not restricting their examination of mosquitoes to WNV alone. In addition, they are also testing mosquitoes for other forms of mosquito-borne diseases, including eastern equine encephalitis (EEE), St. Louis encephalitis and LaCrosse encephalitis.

"The WNV surveillance effort is allowing us to look for other potentially serious diseases as well," says Rossi. "For example, EEE is much more serious and deadly than WNV. " The mortality rate from EEE is more than 30 percent, while it is about 15 percent or less for WNV.

Rossi says the mosquito examination is the most time-consuming and labor-intensive part of the surveillance effort. Mosquitoes must be sorted, identified by species and counted by location. With as many as 6,000 mosquitoes in one collection, the process takes a great deal of effort and man-hours.

"Extension as well as the Alabama Department of Public Health, among others, are all vital partners in the surveillance effort," says Rossi. "The surveillance effort is far too broad to be accomplished without the work of people in a number of cooperating agencies."

Besides humans, horses are particularly vulnerable to both WNV and EEE. More than 160 horses were screened for both diseases last year. In 2001, there were four equine cases of WNV in Alabama. Three of the animals fully recovered, but one had to be euthanized because of the disease. In neighboring Florida, more than 450 horses were infected with WNV.

EEE was identified in 15 Alabama counties, primarily across the southern part of the state. Thirty-six horses tested positive for EEE in 2001. In addition, EEE was also identified in a dog as well as several emus.

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Source: Ashley Rossi, USDA Animal and Plant Health Inspection Service

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Protecting Yourself and Your Animals From Mosquito-Borne Illnesses

Auburn, April 18, 2002---Mosquitoes are the primary carriers for West Nile virus (WNV) and eastern equine encephalitis (EEE). The key to preventing or controlling future outbreaks of both diseases among people, horses and other livestock is to prevent or limit exposure to mosquitoes.

First, reduce mosquito-breeding sites. Reducing the population of mosquitoes can help prevent the spread of these diseases.

You should eliminate potential sources of stagnant water in which mosquitoes might breed. Dispose of any water-holding containers, including discarded tires. Store containers, such as buckets, in garages or barns. If you must leave them outside, turn them over so that they do not collect rainwater. Turn over plastic wading pools or wheelbarrows when not in use.

Clean roof gutters annually.

Do not allow water to stagnate in birdbaths. Aerate ornamental pools or stock them with fish. People with lily ponds can get mosquito fish (Gambusia), which eat larvae and live happily with goldfish.

If the water is constantly moving in an ornamental pond, there generally is not a problem with mosquitoes, unless there are aquatic plants for the larvae to hide among. There are products available to control mosquitoes in the pond. Mosquito dunks or floating Bt briquettes control mosquito larvae and do not harm fish. One briquette lasts about 30 days and treats 100 square feet of surface water. You can find them in pet stores or stores that sell pond supplies.

Clean and chlorinate swimming pools that are not in use. Mosquitoes can breed in the water that collects on swimming pool covers and in clogged filter baskets.

Use landscaping to eliminate standing water that collects on your property. Mosquitoes can breed in any puddle that lasts more than four days.

You may want to fill tree stumps with sand to prevent pools of water from forming in them.

Also, keeping vegetation trimmed low can eliminate resting sites for mosquitoes in the daytime.

Make sure windows and doors have screens that are in good repair. If possible, screen off entrances and vents to the crawl space under your home which is a popular spot for resting mosquitoes. Close openings to abandoned sheds for the same reason.

You can continue your outdoor activities, but you should reduce your risk of being bitten by mosquitoes.

Minimize the amount of time you spend outdoors between dusk and dawn. Wear shoes, socks, long pants and a long-sleeved shirt when outdoors for long periods or when mosquitoes are most active.

You may want to use a mosquito repellent, applied according to label directions, when you are outdoors. Repellents containing 14 percent DEET are considered the most effective for adults. Use products with 10 percent DEET for children under the age of 12.

You should also decrease your animals' exposure to adult mosquitoes.

Housing animals in structures with well-maintained insect screening can reduce exposure to mosquitoes. Be sure to first eliminate mosquitoes from inside the structure. This may be accomplished through a number of means, including the use of mosquito

adulticides. In addition, the use of fans may reduce potential access of mosquitoes to equine or other livestock hosts.

Use of insect repellents may be of some value in decreasing exposure of horses to adult mosquitoes. Due to practical limitations in the coverage area that may be achieved and due to limited duration of effectiveness, repellents should not be solely relied upon to prevent mosquito exposure. Repellents should be used according to their label instructions regarding appropriate species, method of application and other precautions.

Source: Ashley Rossi, USDA

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