West Nile Virus - PowerPoint PPT Presentation

About This Presentation
Title:

West Nile Virus

Description:

Identify the most common route of virus transmission ... Fever, headache, muscle aches, fatigue. Nausea, vomiting. Rash, swollen lymph nodes ... – PowerPoint PPT presentation

Number of Views:328
Avg rating:3.0/5.0
Slides: 20
Provided by: phls2
Learn more at: http://www.nwcphp.org
Category:
Tags: aches | nile | virus | west

less

Transcript and Presenter's Notes

Title: West Nile Virus


1
West Nile Virus
Focus on clinical aspects of human infection
  • Jo Hofmann, MD
  • State Epidemiologist for
  • Communicable Disease
  • Washington State Department of Health

2
Overview and learning objectives
  • Review
  • Clinical features of human West Nile virus (WNV)
    infections
  • Routes of WNV transmission in humans
  • Learning objectives
  • Describe symptoms of the most common illness
    associated with WNV infection
  • Identify the most common route of virus
    transmission
  • Describe two new methods of surveillance for WNV
    infections

3
WNV infection clinical syndromes
  • West Nile fever
  • Mild infection
  • West Nile neuroinvasive disease
  • Meningitis
  • Encephalitis
  • Acute flaccid paralysis (AFP)
  • Polio-like syndrome
  • Movement disorders
  • Involuntary muscle spasms
  • Parkinsons-like syndromes
  • Other neurological manifestations

4
Human infection with WNV
5
West Nile virus infections, by age group
clinical category -- United States, 2003
Source Hayes, N. 5th Natl Conf. on West Nile
Virus, 2004
6
West Nile fever
  • Self-limited illness with sudden onset
  • Fever, headache, muscle aches, fatigue
  • Nausea, vomiting
  • Rash, swollen lymph nodes
  • Symptoms can be debilitating, may persist for
    weeks
  • Does not progress to West Nile neuroinvasive
    disease

7
West Nile neuroinvasive disease
  • The disease formerly known as West Nile
    meningoencephalitis
  • Rarest WNV infection
  • Neurological symptoms occur 1-2 days after onset
    of fever
  • WNND includes
  • Meningitis - stiff neck, headache, abnormal
    cerebrospinal fluid
  • Encephalitis - confusion, seizures
  • Acute flaccid paralysis (AFP)

8
West Nile virus-associated acute flaccid
paralysis (AFP)
  • Rare, cases seen during outbreaks
  • Symptoms look like poliomyelitis (polio)
  • Asymmetrical weakness (left gt right, etc.)
  • No sensory symptoms
  • Abnormal cerebrospinal fluid
  • Affects young, healthy patients compared with
    other WN neuroinvasive disease
  • Fever, headache may be absent
  • May occur with or w/o meningitis or encephalitis

9
Dude, wheres my blood meal?
10
Newly described routes of WNV transmission
  • Transfusion of blood, platelets, fresh frozen
    plasma
  • Organ transplantation
  • Perinatal exposure (infected mother to newborn)
  • Breastfeeding
  • Occupational exposure (laboratory accidents,
    alligator and poultry farming)

11
WNV infections following transfusion
  • First recognized in 2002
  • gt60 suspected cases investigated 23 cases
    confirmed following transfusion from 16 infected
    donors
  • Sources red blood cells, platelets, and plasma
  • Nationwide screening of blood donations began
    July 2003 new method of surveillance for WNV
    infections

12
Screening the blood supply
  • Asking donors about symptoms
  • Screening donations with nucleic acid
    amplification test (NAAT) detects virus
  • Contaminated products destroyed, donors contacted
  • Blood banks report infected blood products to
    state health departments
  • 6.2 million units screened in 2003 gt1000 donors
    infected with WNV reported

13
Confirmed and probable transfusion-associated
WNV infection, 2003
  • Occurred in epicenter of outbreak
  • Three in Texas
  • One each in Nebraska, Iowa, Kansas
  • Onset of symptoms during peak of outbreak August
    through October
  • Average age of cases 63 years
  • Five developed WNND (encephalitis)

14
Perinatal transmission of WNV
  • First described in U.S. in 2002
  • Several children born to mothers with confirmed
    WNV infection
  • Some with neurological defects
  • A large series of cases from 2003-2004 still
    being investigated
  • CDC has on-line reporting site for registry of
    pregnancy-associated cases

15
Coming soon web-based reporting WNV infection
during pregnancy Healthcare providers report
on-line States/local HD informed when their
providers report Providers contacted for
follow-up and specimens needed for testing For
now Call state/local health department or CDC _at_
970-221-6400
16
Summary
  • Most WNV infections are asymptomatic
  • Most common illness is West Nile fever
  • The most common route of transmission is through
    the bite of an infected mosquito
  • Transfusion and pregnancy associated cases
  • Screening of blood donors and web-based reporting
    of pregnancy associated cases are new
    surveillance methods

17
Questions?
18
References
  • Interim guidelines for the evaluation of infants
    born to mothers infected with West Nile virus
    during pregnancy. MMWR 200453154-7
  • Transmission of West Nile virus from an organ
    donor to four transplant recipients. New Engl
    Jour Med 20033482196-2203.
  • Possible West Nile virus transmission to an
    infant through breast-feeding - Michigan 2002.
    MMWR 2002 51877-8.

19
References
  • Petersen LR, Marfin AA. West Nile Virus a primer
    for the clinician. Ann Intern Med 2002137173-9.
  • Investigations of West Nile virus infections in
    recipients of blood transfusions. MMWR
    200251973-4.
  • Neurologic manifestations and outcome of West
    Nile virus infection. JAMA. 2003290511-5.
  • CDC WNV clinical guidance website
  • http//www.cdc.gov/ncidod/dvbid/westnile/clinical
    _guidance.htm
Write a Comment
User Comments (0)
About PowerShow.com