West Nile virus is a disease spread by mosquitos. The condition ranges from mild to severe.
Causes, incidence, and risk factors
West Nile virus was first identified in 1937 in Uganda in eastern Africa. It was first identified in the United States in the summer of 1999 in New York. Since then, the virus has spread throughout the United States.
The West Nile virus is a type of organism called a flavivirus. Researchers believe West Nile virus is spread when a mosquito bites an infected bird and then bites a person.
Mosquitos carry the highest amounts of virus in the early fall, which is why the rate of the disease increases in late August to early September. The risk of disease decreases as the weather becomes colder and mosquitos die off.
Although many people are bitten by mosquitos that carry West Nile virus, most do not know they've been exposed. Few people develop severe disease or even notice any symptoms at all.
Mild, flu-like illness is often called West Nile fever. More severe forms of disease, which can be life threatening, may be called West Nile encephalitis or West Nile meningitis, depending on what part of the body is affected.
Risk factors for developing a more severe form of West Nile virus include:
West Nile virus may also be spread through blood transfusions and organ transplantation. It is possible for an infected mother to spread the virus to her child through breast milk.
Insect bites and stings (26 images)(Doctor-Reviewed information)
Insect bites and stings can cause an immediate skin reaction. The bite from fire ants and the sting from bees, wasps, and hornets are usually painful. Bites caused by mosquitoes, fleas, and mites are more likely to cause itching than pain. Reviewer: John E. Duldner, Jr., MD, MS, Assistant Professor of Emergency Medicine, Director of Research, Department of Emergency Medicine, Akron General Medical Center and Northeastern Ohio Universities College of Medicine. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.Date: 02/19/2008
Encephalitis(Doctor-Reviewed information)
Encephalitis is an inflammation (irritation and swelling) of the brain, usually caused by infections. See also meningitis. Reviewer: Kenneth Gross, M.D., Neurology, North Miami, FL. Review provided by VeriMed Healthcare Network.Date: 09/07/2006
Meningitis (6 images)
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(Doctor-Reviewed information)
Meningitis is a bacterial or non-bacterial infection that causes inflammation of the membranes covering the brain and spinal cord. Reviewer: Arnold L. Lentnek, M.D., Division of Infectious Disease, Kennestone Hospital, Marietta, GA. Review provided by VeriMed Healthcare Network.Date: 11/12/2007
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