BY CINDY RAMEY

West Nile Virus

West Nile Virus

West Nile virus (WNV) is a mosquito-borne zoonotic arbovirus

Family: FlaviviridaeGenus: Flavivirus Japanese Encephalitis

Antigenic ComplexSize: 40-60nm Incubation period: ranges from three to 14

days

West Nile Virus

West Nile Virus was first isolated in the West Nile district of Uganda in 1937

It first appeared in North America in 1999The virus first was reported in Oregon in 1999When it re-surfaced three years ago in 2009,

a total of 12 cases were reported

Transmission of West Nile Virus

Most West Nile virus infections occur during warm weather, when mosquito populations are active

Infectious mosquitoes carry virus particles in their salivary glands and infect susceptible bird species during blood-meal feeding

The bite of an infected mosquito infects human hosts

Transmission of West Nile Virus Cont.

Risk Factors

Age. Adults over the age of 50 are at higher risk of infection.

Health. Those who have a weakened immune system, such as from receiving an organ transplant, are at greater risk of infection.

Signs and Symptoms

Most people who are infected with West Nile Virus show no signs or symptoms

Some develop a life-threatening illness that includes inflammation of the brain (encephalitits)

Mild signs and symptoms of a West Nile virus infection generally go away on their own

But severe signs and symptoms — such as a severe headache, disorientation or sudden weakness — require immediate attention

Mild Signs and Symptoms Include

FeverHeadacheBody achesFatigueSkin rash (occasionally)Swollen lymph glands (occasionally)Eye pain (occasionally)

Severe Signs and Symptoms Include

High feverSevere headacheStiff neckDisorientation or confusionStupor or comaTremors or muscle jerkingLack of coordinationConvulsionsPainPartial paralysis or sudden weakness

Prevention of West Nile Virus

Avoid areas where West Nile Virus is commonUse mosquito repellent Wear clothing that covers your skin Avoid areas of stagnant water

Interesting Factoids

West Nile virus has been detected in dead birds of at least 326 species

Diagnosis of West Nile Virus

Laboratory testsIf you are infected, a blood test may show a

rising level of antibodies to the West Nile virusA positive ribonucleic acid (RNA) test for the

West Nile virus also is an indicator that you have the virus

Diagnosis of West Nile Virus Cont.

Lumbar puncture (spinal tap)The most common way to diagnose West Nile

Virus is to analyze the cerebrospinal fluid surrounding your brain and spinal cord

A needle inserted between the lower vertebrae of your spine is used to extract a sample of fluid for laboratory analysis

Brain testsIn some cases, an electroencephalography (EEG)

or an MRI scan can help detect brain inflammation

Treatment of West Nile Virus

Supportive therapy Most people recover from West Nile virus

without treatmentOver-the-counter pain relievers can help ease

mild headaches and muscle painSupportive therapy in a hospital with

intravenous fluids and medicines may prevent other types of infections

Treatment of West Nile Virus Cont.

Interferon therapy An experimental type of immune cell therapy

as a treatment for encephalitis caused by West Nile virus

Some research shows that people who receive interferon may recover better than those who don't receive the drug, but more study is needed

West Nile Virus Case Study October 23, 2012

As of October 23, 2012, 48 states have reported West Nile virus infections in people, birds, or mosquitoes 4,725 cases 219 deaths 2,413 (51%) were classified as neuroinvasive

disease (such as meningitis or encephalitis) 2,312 (49%) were classified as non-neuroinvasive

disease

West Nile Virus Case Study October 23, 2012

Almost 70 percent of the cases have been reported from eight states Texas, California, Louisiana, Mississippi, Illinois,

South Dakota, Michigan, and Oklahoma

Over a third of all cases have been reported from Texas.

Cases of West Nile Virus in Oregon

According to the CDC Oregon has had a mere 3 cases of West Nile Virus in 2012. None of these documented cases were neuroinvasive and no deaths have been reported. However, that is an increase from 2011 where no cases were reported. Other states have not been so fortunate. Although the cases in Oregon are minimal compared to those in other states, West Nile Virus is still very much a concern and precautions should always be taken to prevent infection.

Importance of Studying West Nile Virus

West Nile Virus has become more common since the spread of the disease to the United States in 1999. The recent epidemic is proof that the disease is very real and can be life threatening. Understanding the disease, how to prevent it, and what signs and symptoms to look for will make sure that you do not become a statistic of this serious virus.

Websites

http://www.mayoclinic.com/health/west-nile-virus/DS00438

http://www.cdc.gov/ncidod/dvbid/westnile/cycle.htm

http://abcnews.go.com/Health/west-nile-virus-doctors-fight-largest-outbreak-us/story?id=17254382#.UI8mZ2dNKSo

http://en.wikipedia.org/wiki/West_Nile_virus