Manifestations include a nonspecific minor illness abortive poliomyelitis , sometimes aseptic meningitis without West Nile virus acute flaccid paralysis can occur without fever or apparent viral prodrome and often presents as isolated limb paresis or paralysis and may progress to respiratory paralysis requiring mechanical ventilation. Most people with typical fever and myalgia recover completely, but fatigue and weakness can last for weeks or months.
Patients who recover from West Nile virus encephalitis or acute flaccid paralysis often have residual neurologic deficits.
These antibodies are usually detectable 3 to 8 days after onset of illness and persist for 30 to 90 days, but longer persistence has been documented. False-positive results may result from cross-reactive antibodies due to infection with other flaviviruses, recent immunization with flavivirus vaccines yellow fever or Japanese encephalitis , or from nonspecific reactivity.
Plaque-reduction neutralization tests PRNTs done in reference laboratories, including some state public health laboratories and the Centers for Disease Control and Prevention CDC , can help determine the specific infecting flavivirus, including West Nile virus.
PRNTs can also confirm acute infection by demonstrating a fourfold or greater change in West Nile virus-specific neutralizing antibody titer between acute- and convalescent-phase serum samples collected 2 to 3 weeks apart. Close monitoring of patients with encephalitis for the development of elevated intracranial pressure and seizures. Close monitoring of patients with encephalitis or acute flaccid paralysis for inability to protect their airway. It is caused by intrapulmonary shunting of blood resulting from airspace filling or Personal protective measures to decrease exposure to infected mosquitoes, including using diethyltoluamide DEET , mosquito netting, and protective attire.
Blood and some organ donors are screened for West Nile virus by nucleic acid—based tests. Healthcare professionals should remain vigilant for the possible transmission of West Nile virus through blood transfusion or organ transplantation.
There is no evidence that humans acquire West Nile virus infection from handling dead or infected birds, but the CDC still recommends wearing gloves when handling dead birds or any animal. Petersen LR. Epidemiology and pathogenesis of West Nile virus infection. Clinical manifestations and diagnosis of West Nile virus infection.
West Nile virus infection. Mayo Clinic; Treatment and prevention of West Nile virus infection. Tosh PK expert opinion. Mayo Clinic. Severe illness can occur in people of any age; however, people over 60 years of age are at greater risk for severe illness if they are infected 1 in 50 people. People with certain medical conditions, such as cancer, diabetes, hypertension, kidney disease, and people who have received organ transplants, are also at greater risk.
Recovery from severe illness might take several weeks or months. Some effects to the central nervous system might be permanent. About 1 out of 10 people who develop severe illness affecting the central nervous system die. Diagnosis See your healthcare provider if you develop the symptoms described above. Your healthcare provider can order tests to look for West Nile virus infection. A mosquito bite can turn into something much more severe if it infects you with the West Nile virus sometimes called WNV.
Mosquitoes transmit this virus by biting an infected bird and then biting a person. Not all people with infected mosquito bites get the disease, however. WNV can be severe for people older than 60 years and people with weakened immune systems. If diagnosed and treated quickly, the outlook for West Nile virus recovery is good. If you have West Nile virus, you will typically show the first virus symptoms within three to 14 days of being bitten.
West Nile virus symptoms vary in severity. Severe symptoms can include:. A severe infection can last for several weeks. In rare cases, a severe infection can cause permanent brain damage. Mild forms of West Nile virus may be confused with the flu.
Symptoms include:. Infected mosquitoes usually spread the West Nile virus. The mosquito first bites an infected bird and then bites a human or another animal. In rare cases, blood transfusions, organ transplants, breastfeeding, or pregnancy can transfer the virus and spread the illness. Anyone bitten by an infected mosquito can get West Nile virus. However, less than one percent of people who are bitten develop severe or life-threatening symptoms.
Age is one of the most significant risk factors for developing severe symptoms from a West Nile infection. In most cases, your doctor can diagnose West Nile virus with a simple blood test. This can determine whether you have genetic material or antibodies in your blood associated with West Nile virus.
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