WEST NILE FEVER

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WEST NILE FEVER

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WEST NILE FEVER

  1. 1. WEST NILE FEVER Dr.T.V.Rao MD
  2. 2. WEST NILE VIRUS West Nile virus (WNV) is a mosquito- borne zoonotic arbovirus belonging to the genus Flavivirus in the family Flaviviridae. This flavivirus is found in temperate and tropical regions of the world. It was first identified in the West Nile sub region in the East African nation of Uganda in 1937
  3. 3. FLAVIVIRUS
  4. 4. WEST NILE VIRUS West Nile virus belongs to a family of viruses called Flaviviridae. It is spread by mosquitoes that have fed on the blood of infected birds. West Nile virus is closely related to the viruses that cause Dengue fever, Yellow fever and St. Louis encephalitis
  5. 5. WHAT TYPES OF BIRDS CARRY WEST NILE VIRUS? The virus has been found in more than 150 bird species in North America. Some species may have no obvious signs of illness when infected. Others, such as crows, blue jays, magpies and ravens, get sick more often and can die.
  6. 6. WEST NILE VIRUS (WNV) IS MOST COMMONLY TRANSMITTED TO HUMANS BY MOSQUITOES. Transmitted by
  7. 7. OTHER ROUTES OF TRANSMISSION Additional routes of human infection have also been documented. It is important to note that these methods of transmission represent a very small proportion of cases: Blood transfusions Organ transplants Exposure in a laboratory setting From mother to baby during pregnancy, delivery, or breastfeeding
  8. 8. NO SYMPTOMS IN MOST PEOPLE. MOST PEOPLE (70- 80%) WHO BECOME INFECTED WITH WEST NILE VIRUS DO NOT DEVELOP ANY SYMPTOMS. May be Asymptomatic
  9. 9. FEBRILE ILLNESS IN SOME PEOPLE About 1 in 5 people who are infected will develop a fever with other symptoms such as headache, body aches, joint pains, vomiting, diarrhoea, or rash. Most people with this type of West Nile virus disease recover completely, but fatigue and weakness can last for weeks or months.
  10. 10. SEVERE SYMPTOMS Severe symptoms in a few people. Less than 1% of people who are infected will develop a serious neurologic illness such as encephalitis or meningitis (inflammation of the brain or surrounding tissues).
  11. 11. THE SYMPTOMS OF NEUROLOGIC ILLNESS CAN INCLUDE HEADACHE, HIGH FEVER, NECK STIFFNESS, DISORIE NTATION, COMA, TR EMORS, SEIZURES, OR PARALYSIS. Can Manifest with Neurological illness
  12. 12. OTHER PREDISPOSING CONDITIONS People with certain medical conditions, such as cancer, diabetes, hypertension and kidney disease are also at greater risk for serious illness .Recovery from severe disease may take several weeks or months. Some of the neurologic effects may be permanent. About 10 percent of people who develop neurologic infection due to West Nile virus will die.
  13. 13. LABORATORY CRITERIA FOR DIAGNOSIS Isolation of virus from, or demonstration of specific viral antigen or nucleic acid in, tissue, blood, CSF, or other body fluid, OR Four-fold or greater change in virus-specific quantitative antibody titers in paired sera,
  14. 14. DETECTION OF IGM CAN USEFUL IN ROUTINE TESTS WNV-specific IgM 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. Therefore, positive IgM antibodies occasionally may reflect a past infection. If serum is collected within 8 days of illness onset, the absence of detectable virus-specific IgM does not rule out the diagnosis of WNV infection, and the test may need to be repeated on a later sample.
  15. 15. DETECTION OF IGG INDICATES PAST INFECTION WNV IgG antibodies generally are detected shortly after IgM antibodies and persist for many years following a symptomatic or asymptomatic infection. Therefore, the presence of IgG antibodies alone is only evidence of previous infection and clinically compatible cases with the presence of IgG, but not IgM, should be evaluated for other etiologic agents.
  16. 16. REFERENCE LABORATORY TESTS Plaque-reduction neutralization tests (PRNTs) performed in reference laboratories, including some state public health laboratories and CDC, can help determine the specific infecting flavivirus.
  17. 17. OTHER TESTING FOR WNV DISEASE Viral cultures and tests to detect viral RNA (e.g., reverse transcriptase- polymerase chain reaction [RT-PCR]) can be performed on serum, CSF, and tissue specimens that are collected early in the course of illness and, if results are positive, can confirm an infection.
  18. 18. TREATMENT No vaccine or specific antiviral treatments for West Nile virus infection are available. Over-the-counter pain relievers can be used to reduce fever and relieve some symptoms In severe cases, patients often need to be hospitalized to receive supportive treatment, such as intravenous fluids, pain medication, and nursing care.
  19. 19. PREVENTION & CONTROL The most effective way to avoid West Nile virus disease is to prevent mosquito bites. Be aware of the West Nile virus activity in your area and take action to protect yourself and your family.
  20. 20. USE OF INSECT REPELLENTS Use insect repellents when you go outdoors. Repellents containing DEET, picaridin, IR3535, an d some oil of lemon eucalyptus and para- menthane-diol products provide longer-lasting protection. To optimize safety and effectiveness, repellents should be used according to the label instructions
  21. 21. Programme Created and Designed by Dr.T.V.Rao MD for Medical and Paramedical Students on global Education of Infectious Diseases Email doctortvrao@gmail.com

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