West Nile Virus: What You Need To Know
Overview of West Nile
Virology: Classification of West Nile Virus
 |
 |
Image A |
Image B |
Scanned images are of West Nile virus isolated from brain tissue from a crow found in New York. The tissue was cultured in a Vero cell for a 3-day incubation period. The Vero cells were fixed in glutaraldehyde, dehydrated, placed in an Epon resin, thin sectioned, placed on a copper grid, and stained with uranyl acetate and lead citrate. The grids were then placed in the electron microscope and viewed. Total magnifications, image A: 65,625x; |
|
- Family: Flaviviridae
- Genus: Flavivirus Japanese Encephalitis Antigenic Complex
- Complex includes: Alfuy, Cacipacore, Japanese encephalitis, Koutango, Kunjin, Murray Valley encephalitis, St. Louis encephalitis, Rocio, Stratford, Usutu, West Nile, and Yaounde viruses.
- Flaviviruses: share a common size (40-60nm), symmetry (enveloped, icosahedra nucleocapsid), nucleic acid (positive-sense, single stranded RNA approximately 10,000-11,000 bases), and appearance in the electron microscope. Therefore, images of West Nile virus are representative for this group of viruses.
Q: What is West Nile?
A: West Nile is a flavivirus commonly found in
Africa, West Asia and the Middle East. It is closely related to
the St. Louis encephalitis virus which is also found in the United
States. The virus can infect humans, birds, mosquitoes, horses and
some mammals. West Nile virus is a potentially serious illness.
West Nile virus is established as a seasonal epidemic in North America
that flares up in the summer and continues into fall. In the southern
climates where temperatures are milder, West Nile virus can be transmitted
year round.
Q: How do people get infected with West Nile virus?
A: The main route of human infection with West
Nile virus is through the bite of an infected mosquito. Mosquitoes
become infected when they feed on infected birds, which may circulate
the virus in their blood for a few days. The virus eventually gets
into the mosquito’s salivary glands. During later blood meals
(when mosquitoes bite), the virus may be injected into humans and
animals, where it can multiply and possibly cause illness.
Q: How does West Nile Virus actually cause sever 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 are the Symptoms of West Nile Virus? (Statistics
provided by CDC)
A: West Nile Virus affects the central nervous
system. Symptoms vary.
- No Symptoms. Approximately 80 percent of people who are infected with the West Nile Virus will not show any symptoms at all.
- Mild Symptoms. Up to 20 percent of the people who become infected will display mild symptoms, including fever, headaches, and body aches, nausea, vomiting and sometimes swollen lymph glands or a skin rash on the chest, stomach and back. Symptoms typically last a few days.
- Serious Symptoms. The severe symptoms can include high fever, headache, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness, vision loss, numbness and paralysis. These symptoms may last several weeks and neurological effects may be permanent.
Q: How soon do infected individuals start displaying symptoms?
A: People typically develop symptoms between 3
and 14 days after they are bitten by the infected mosquito.
Q: Who is at risk contracting West Nile Virus?
A: For most the risk is low. However, there is
a greater risk for those outdoors a lot. People who spend a lot
of time outdoors are more likely to be bitten by an infected mosquito.
They should take special care to avoid mosquito bites. Furthermore,
people over 50 are more likely to develop serious symptoms of West
Nile Virus if they do get sick and should take special care to avoid
mosquito bites.
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.
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 you get West Nile Virus from eating game birds or
animals that have been infected?
A: There is no evidence that West Nile virus can
be transmitted to humans through consuming infected birds or animals.
In keeping with overall public health practice, and due to the risk
of known food-borne pathogens, people should always follow procedures
for fully cooking meat from either birds or mammals.
Q:
What can I do to Prevent West Nile Virus?
A: The easiest and best way to avoid West Nile
Virus is to prevent mosquito bites.
- Notify the City of Albuquerque Bio-Disease Management Program:
- Mosquito Complaint Form Report areas that have a high mosquito population.
- Mosquito Fish Request Form Assist the City in controling mosquitos in Albuquerque by using Gambusie (Mosquito Fish) to eat the mosquito larvae.
- When you are outdoors, use insect repellants containing DEET (N, N-diethyl-meta-toluamide). Follow the directions on the package. (When an how to apply repellant, see Insect Repellent Use and Safety [http://www.cdc.gov/ncidod/dvbid/westnile/qa/insect_repellent.htm] or Using Insect Repellent Safely [http://www.epa.gov/pesticides/factsheets/alpha_fs.htm] and you can get additional information at the National Pesticide Information Center at 1-800-858-7378).
- Many mosquitoes are most active at dusk and dawn. Consider staying indoors during these times or use insect repellant and wear long sleeves and pants. Light – colored clothing can help you see mosquitoes that land on you.
- Make sure you have good screens on your windows and doors to keep mosquitoes out.
- Get rid of mosquito breeding sites by emptying standing water from flower pots, buckets and barrels.
- Change the water in pet dishes and replace the water in bird baths weekly.
- Keep children’s wading pools empty and on their sides
when they aren’t
being used.