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Black Pathogen: Attack of the Nile What is the West Nile Virus? West Nile encephalitis is an infection of the brain that is caused by a virus known as the West Nile Virus, otherwise known as the mosquito-borne disease. First identified in Uganda in 1937, the virus is commonly found in Africa, West Asia and the Middle East. It did not spread to the U.S. for another 60 years. “Encephalitis" means inflammation of the brain. One of the causes of encephalitis is viral and bacterial infections, including viral infections transmitted by mosquitoes.

West Nile Virus (WNV) infection of mosquitoes, birds, and vertebrates continues to spread in the Western Hemisphere. In humans, WNV infects the central nervous system and causes severe disease, primarily in the immunocompromised and elderly. Recent virologic, immunologic and structural experiments have enhanced our understanding on how antibodies neutralize WNV and protect against disease.

Outline 1.Causes 1.1 Roles 2.Symptoms 3.Signs & Tests 3.1 Diagnosis 4.Treatment 4.1 Therapy 5.Prevention 6.Pathogenicity 6.1 Structures 6.2 Mechanisms 7.History 8.Exteral Links 8.1 Journal Articles 8.2 References

Causes

Roles

Symptoms

Signs & Tests Most people infected with the West Nile virus have no signs or symptoms. About 20 percent of people develop a mild infection called West Nile fever. Common signs and symptoms of West Nile fever include: •Fever •Headache •Muscle aches •Backache •Lack of appetite •Nausea, vomiting and diarrhea •Skin rash •Swollen lymph glands

In less than 1 percent of infected people, the virus causes a more serious neurological infection, such as inflammation of the brain (encephalitis) or of the brain and surrounding membranes (meningoencephalitis), infection and inflammation of the membranes surrounding the brain and spinal cord (meningitis), and paralysis. Signs and symptoms of these diseases include: •High fever •Severe headache •Stiff neck •Disorientation or confusion •Stupor or coma •Tremors or muscle jerking •Signs and symptoms of Parkinson's disease •Lack of coordination •Convulsions •Partial paralysis

Symptoms of West Nile fever usually last a few days, but symptoms of encephalitis or meningitis can linger for weeks, and certain neurological effects, such as paralysis, may be permanent. Signs of West Nile virus infection are similar to those of other viral infections. There is nothing that can be found on physical examination to diagnose West Nile virus infection. A rash is present in 20-50% of patients. True muscle weakness in the presence of other related symptoms is suggestive of West Nile virus infection.

Tests to diagnose West Nile virus include: •CBC •Lumbar puncture and cerebrospinal fluid (CSF) testing •Head CT scan •Head MRI scan However, the most accurate way to diagnose this infection is a serology test, which checks a blood or CSF sample for antibodies against the virus. Rarely, a sample of blood or CSF may be sent to a lab to be cultured to look for the presence of West Nile virus. The virus can also be identified in body fluids using a technique called polymerase chain reaction (PCR). However, these methods can provide false negative results. Signs and symptoms

Symptoms of West Nile fever usually last a few days, but symptoms of encephalitis or meningitis can linger for weeks, and certain neurological effects, such as paralysis, may be permanent.

Diagnosis

Treatment

Therapy

Prevention The CDC has been working with the Environmental Protection Agency as well as other federal, state and local agencies to prevent future outbreaks of West Nile virus. Efforts to detect and contain the virus include: •Sampling of mosquito and bird populations for West Nile virus •Increased surveillance of animals and humans for infection •Eliminating mosquito-breeding areas •Increased physician awareness and reporting of the virus so that its spread can be tracked •Conducting public-awareness campaigns to let people know how to reduce their risk of exposure to the virus

Your best bet for preventing West Nile virus and other mosquito-borne illnesses is to avoid exposure to mosquitoes and eliminate mosquito-breeding sites. To help control West Nile virus: •Eliminate standing water in your yard. Mosquitoes breed and multiply in pools of standing water. •Unclog roof gutters. •Empty unused swimming pools. •Change water in birdbaths at least weekly. •Remove old tires or any unused containers that might hold water and serve as a breeding ground for mosquitoes. •Watch for sick or dying birds and report them to your local health department.

To reduce your own exposure to mosquitoes: •Avoid unnecessary outdoor activity when mosquitoes are most prevalent, such as at dawn, dusk and early evening. •Wear long-sleeved shirts and long pants when you go into mosquito-infested areas. •Apply mosquito repellent with a 10 percent to 30 percent concentration of DEET to your skin and clothing. Choose the concentration based on the hours of protection you need — a 10 percent concentration is effective for about two hours, while higher concentrations last longer. Keep in mind that chemical repellants can be toxic, and use only the amount needed for the time you'll be outdoors. Don't use DEET on the hands of young children or on infants under 2 months of age. Instead, cover your infant's stroller or playpen with mosquito netting when outside. According to the CDC, oil of lemon eucalyptus, a more natural product, offers the same protection as DEET when used in similar concentrations. Other natural repellants, such as citronella and oil of geranium, also offer some protection. A vaccine is available to protect horses from West Nile virus. No vaccine is yet available for humans, but work to develop a human vaccine is under way.

Pathogenicity

Structures

Mechanisms

History

External Links

Journal Articles

References 1.www.mecidinenet.com 2.www.mayoclinic.com 3.www.CNN.com 4.WebMD 5.“Human Antibody Therapeutics for Viral Diseases”, Springer, Berlin, Heidelberg, 2008 6.Departments of Medicine, Molecular Microbiology, Pathology & Immunology, Washington University School of Medicine, 660 South Euclid Avenue, 8051, 63110, St. Louis, MO USA 7.www.cdc.gov []