West Nile Virus

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(The following information is provided by the Center for Disease Control and the Georgia Department of Human Resources - Public Health Section)

We have received notification from the state office that because of the overwhelming number of birds being sumitted for testing, we will only submit crows, bluejays, & raptors, effective immediately. These birds are considered to be more susceptible to the virus. Review updated list from Georgia Division of Public Health and current affected counties .

BACKGROUND
Introduction:
West Nile (WN) virus has emerged in recent years in temperate regions of Europe and North America, presenting a threat to public, equine, and animal health. The most serious manifestation of West Nile Virus infection is fatal encephalitis (inflammation of the brain) in humans and horses, as well as mortality in certain domestic and wild birds.

History:
West Nile virus was first isolated from a febrile adult woman in the West Nile District of Uganda in 1937. The ecology was characterized in Egypt in the 1950s. The virus became recognized as a cause of severe human meningoencephalitis (inflammation of the spinal cord and brain) in elderly patients during an outbreak in Israel in 1957. Equine disease was first noted in Egypt and France in the early 1960s. The appearance of WN virus in North America in 1999, with encephalitis reported in humans and horses, may be an important milestone in the evolving history of this virus.

Geographic Distribution:
West Nile virus has been found in Africa, Europe, the Middle East, west and central Asia, Oceania (subtype Kunjin), and most recently, North America. Recent outbreaks of WN virus encephalitis in humans have occurred in Algeria in 1994, Romania in 1996-1997, the Czech Republic in 1997, the Democratic Republic of the Congo in 1998, Russia in 1999, the United States in 1999-2000, and Israel in 2000. Epizootics of disease in horses occurred in Morocco in 1996, Italy in 1998, the United States in 1999-2000, and France in 2000. In the U.S. through September 2000, WN virus has been documented in Connecticut, Maryland, Massachusetts, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, the District of Columbia, and most recently in Florida.

How can I prevent myself from being infected with the West Nile Virus?
The best way to prevent infections with West Nile Virus and other mosquito-borne diseases is to avoid getting mosquito bites. Other viruses that are transmitted by mosquitoes, including those that cause St. Louis Encephalitis (SLE) and Eastern Equine Encephalitis (EEE), already exist in Georgia and you can take the following precautions to protect yourself and your family against them:

  • Even in the daytime, when you go outdoors, cover up by wearing shoes, socks, long-sleeved shirts, and long pants. Use mosquito repellant on exposed skin.
  • Use insect repellants with not more than 30% DEET, but use sparingly. Use products containing 15% or less DET for children. DO NOT use products containing DEET on infants. Carefully read and follow direction on the container and wash treated skin when mosquito exposure has ended.
  • Make sure your home, porch, and patio have tight-fitting screens that keep mosquitoes out.
  • All mosquitoes need standing water for the first stages of development. Eliminate stagnant water around your home, where mosquitoes can lay eggs, by disposing of old tin cans, jars, tires, plant pots, and any other container that can hold water. In the spring, inspect rain gutters and downspouts and remove any leaves and other debris. Stack wheelbarrows, tubs, buckets, barrels, boats or canoes, etc. upside down so that water cannot accumulate in them. Empty stagnant bird baths, lily ponds, small wading pools, etc. at least once a week. Properly maintain backyard swimming pools to discourage the development of mosquitoes. Cover any pool not in use so rainwater and leaves do not accumulate in it. Be sure the cover does not hold pockets of water.

Who should I contact for more information?
For general information about West Nile virus and surveillance for vector-borne diseases in Georgia, call the Georgia Department of Human Resources, Division of Public Health:

  • Cathy Rebmann, 404-657-2606 or email
  • Susan Lance-Parker, 404-657-2617 or email

If you would like more information about the West Nile Virus or other mosquito-transmitted diseases, please call the Columbia County Health Department at 706-868-3330.

Frequently Asked Questions

Q. How do people get West Nile encephalitis?
A. By the bite of mosquitoes infected with West Nile virus.

Q. What is the basic transmission cycle?
A. Mosquitoes become infected when they feed on infected birds, which may circulate the virus in their blood for a few days. Infected mosquitoes can then transmit West Nile virus to humans and animals while biting to take blood. The virus is located in the mosquito's salivary glands. During blood feeding, the virus may be injected into the animal or human, where it may multiply, possibly causing illness.

Q. If I live in an area where birds or mosquitoes with West Nile virus have been reported and a mosquito bites me, am I likely to get sick?
A. No. Even in areas where mosquitoes do carry the virus, very few mosquitoes-much less than 1%-are infected. If the mosquito is infected, less than 1% of people who get bitten and become infected will get severely ill. The chances you will become severely ill from any one mosquito bite are extremely small.

Q. Can you get West Nile encephalitis from another person?
A. No. West Nile encephalitis is NOT transmitted from person-to-person. For example, you cannot get West Nile virus from touching or kissing a person who has the disease, or from a health care worker who has treated someone with the disease.

West Nile Virus Transmission Cycle


Q. Is a woman's pregnancy at risk if she gets West Nile encephalitis?
A. There is no documented evidence that a pregnancy is at risk due to infection with West Nile virus.

Q. Besides mosquitoes, can you get West Nile virus directly from other insects or ticks?
A. Infected mosquitoes are the primary source for West Nile virus. Although ticks infected with West Nile virus have been found in Asia and Africa, their role in the transmission and maintenance of the virus is uncertain. However, there is no information to suggest that ticks played any role in the cases identified in the United States.

Q. How many types of animals have been found to be infected with West Nile virus?
A. Although the vast majority of infections have been identified in birds, through September 2000 CDC has received reports of WN virus infection in horses, cats, bats, chipmunks, skunks, squirrels, domestic rabbits, and raccoons.

Q. Can you get West Nile virus directly from birds?
A. There is no evidence that a person can get the virus from handling live or dead infected birds. However, persons should avoid bare-handed contact when handling any dead animals and use gloves or double plastic bags to place the carcass in a garbage can.

Q. Can I get infected with West Nile virus by caring for an infected horse?
A. West Nile virus is transmitted by infectious mosquitoes. There is no documented evidence of person-to-person or animal-to-person transmission of West Nile virus. Normal veterinary infection control precautions should be followed when caring for a horse suspected to have this or any viral infection.

Q. How does West Nile virus actually cause severe illness and death in humans?
A. Following transmission by an infected mosquito, West Nile virus multiplies in the person's blood system and crosses the blood-brain barrier to reach the brain. The virus interferes with normal central nervous system functioning and causes inflammation of brain tissue.

Q. What proportion of people with severe illness due to West Nile virus die?
A. Among those with severe illness due to West Nile virus, case-fatality rates range from 3% to 15% and are highest among the elderly. Less than 1% of those infected with West Nile virus will develop severe illness.

Q. If a person contracts West Nile virus, does that person develop a natural immunity to future infection by the virus?
A. It is assumed that immunity will be lifelong; however, it may wane in later years.

FLASH POINTS!
Talking points on: WEST NILE VIRUS


West Nile virus in pets:

  • West Nile virus is a rare disease and is not known to spread directly from animal to human; only through mosquitoes that have fed on infected birds.
  • The College of Veterinary Medicine at the University of Illinois in Champaign-Urbana, Illinois documented the first known cases in the country of a dog, a wolf and three gray squirrels. (announced on Tuesday, September 17)
  • Dog was an 8-year old Irish Setter-golden retriever mix with various health concerns, recently relocated to Bloomington, Illinois from California.
AT RISK:
  • West Nile virus is mainly a disease of birds and occasionally humans and horses. Mosquitoes that feed on birds transmit the disease to humans and other mammals through subsequent bites.
  • Horses and humans are most likely to be affected by the disease.
  • Elderly dogs or those with compromised immune systems could be at higher risk.   
  • Pets have been exposed but not fallen ill in great numbers.   
  • This is only the second reported illness in a dog in the world. (The other was in Botswana, Africa)
West Nile virus in other animals:
  • West Nile virus has been reported in many species of animals but rarely causes clinical disease.
Diagnosis and treatment:
  • Diagnosis is based on history of exposure, clinical signs, and results of diagnostic blood tests.
  • Treatment consists of providing support (Hospitalization, IV fluids, respiratory support, prevention of secondary infections, and good nursing care) while the individual's immune system responds to the infection.
Prevention:
  • Keep pets indoors at dusk and in the early morning.   
  • DEET (Insect repellent) should not be used on pets. The concentrations of DEET used in commercial mosquito products for humans are too strong to be safely used on cats and dogs. They may develop significant neurologic problems.
  • West Nile virus vaccine is available for the equine population. The vaccine is not approved for use in dogs or cats.
  • Insecticides-repellants containing pyrethrins or permethrin are sometimes labeled with mosquito repellant claims.
Reduce Pet Exposure to Pesticides Used for Mosquito Control
  • Know when pesticides will be sprayed in your community.
  • Keep pets indoors during times when pesticides are being sprayed. Elderly or debilitated animals or those with preexisting health conditions, such as heart disease or asthma, may be more sensitive to airborne pesticides and chemicals.
  • Close windows and turn off window-unit air conditioners when spraying is taking place in the immediate area.
  • Bring pet dishes, toys, and other items inside while pesticides are being sprayed. If these items have been accidentally exposed to the spray, wash the items with soap and water and rinse well before reintroducing the items to your pets.
  • Horses should be kept in their stalls or in a lean-to during spraying.
  • Cover water troughs and water buckets.
  • Cover fishponds during spraying, as fish can be sensitive to certain pesticides.
  • If you suspect that your pet is experiencing difficulties, contact your veterinarian immediately.
RESOURCES:
  • AVMA Web site: www.avma.org, FAQs, brochure, press releases and links to other sources of information.

GEORGIA PUBLIC HEALTH OFFICIAL INITIATE NEW MOSQUITO SURVEILLANCE PROGRAM

The Columbia County Health Department will no longer be shipping dead birds for West Nile Virus testing. However, we will still maintain a dead bird log. This year, we have shipped nearly 30 birds and none have tested positive for WNV. This is a drastic change from last year. During the year 2002 we shipped 11 dead birds, 5 of which tested positive for WNV. According to reports from the Georgia Division of Public Health, this trend has been identified statewide. During the past two years, dead bird testing played a very important role in predicting human risk and local transmission of WNV in Georgia. However, it has caused the public to focus their attentions on dead birds instead of mosquitoes. Many people remain uninformed and have the misconception that WNV can be acquired from dead birds. It must be understood that birds are not the problem- mosquitoes are the problem.

We have been advised by the Georgia Division of Public Health to shift our surveillance from birds to mosquitoes. We will be setting mosquito traps in various areas throughout the county. Once the mosquitoes are trapped they will be sorted and shipped to the College of Veterinary Medicine, University of Georgia to be tested for WNV, EEE, SLE and other arboviruses. The information obtained from the mosquito surveillance program is to be used for research and educational purposes only.

Because of the topography, climate and amount of yearly rainfall, Georgia provides a perfect environment for mosquitoes. Because of an increase in rainfall this year, the mosquitoes are even worse. The number of complaints our office has received regarding mosquitoes has also increased. The best way to mitigate the mosquito population is for everyone to take an active role in being responsible for their own yards and neighborhoods. The most important message for the public is to focus on personal protection from mosquitoes for themselves and their families.

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