Title: UIC School of Public Health October Deans Forum: West Nile Virus Update
1UIC School of Public HealthOctober Deans
Forum West Nile Virus Update
2What is West Nile Virus (WNV)?
- Arbovirus (arthropod-borne virus)
- Flavivirus family Yellow Fever, Dengue, St.
Louis Encephalitis Viruses - Transmitted among various species of birds
primarily through mosquitoes (Culex and others) - 1937 Isolated from blood of woman in West Nile
district, Uganda
3What is West Nile Virus (WNV)?
- 1957 cause of encephalitis (spinal cord and
brain infection) in elderly patients during
outbreak in Israel. - 1960s Horse infections Egypt France
- Currently endemic in Africa, the Middle East, and
Southwestern Asia
4Human/Equine Epidemics
- Israel 1951-54, 57 Congo 1998
- France 1962 Italy 1998
- South Africa 1974 Russia 1999
- Algeria 1994 USA 1999-02
- Romania 1996-97 Israel 2000
- Morocco 1996 France 2000
5A New Disease? NYC, 1999
WNV
- Massive die-off of local birds
- Sudden, unusual cluster of encephalitis (SLE?)
Bird Disease same as Human Disease?
Birds confirmed with WNV
Humans confirmed with WNV
August 1999
September 1999
6Lanciotti et al. Science 2862333-337
7Lanciotti et al. Science 2862333-337
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9Lessons from NYC Outbreak
- Serosurvey 6 weeks after outbreak peak
- 2.6 infected with WNV
- 0.5 non-specific West Nile fever
- 1 of 5 infected persons
- 0.02 developed West Nile Encephalitis
- 1 of 140 infected persons
- RISK FACTOR spending time outdoors near dawn and
dusk - PROTECTIVE using insect repellent
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12NYC, 2001
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14 WNV dead bird Forest preserve
15 WNV dead bird Forest preserve
16National, through 2001
17National, through 2002
18National, through 2002
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21WNV Spectrum of Illness
- Most infections clinically silent
- Milder illness non-specific flu-like symptoms
- Prominent myalgias, backaches, arthralgias
- Occasional rash (20), lymph node swelling
- Severe illness
- Aseptic meningitis Fever, headache, stiff neck
- Encephalitis Mental changes ? coma, death
- Myelitis Polio-like, fever with flaccid
paralysis - Elderly/immunocompromised at high risk
- Diabetics, Hypertensives
22Laboratory Findings
- Total WBC usually normal or ?
- Low WBC and anemia also occurrs
- Serum sodium sometimes ?
- Examination of cerebrospinal fluid (CSF) typical
for a viral meningoencephalitis - Lymphocytes in CSF
- Protein ?, Glucose normal
23Radiographic Imaging
- CAT scans mostly normal
- Magnetic resonance imaging (MRI) ? inflammation
of leptomeninges, the periventricular areas, or
both
24Diagnosis
- West Nile virus or viral RNA in serum,
cerebrospinal fluid, or other tissue. - Isolation from culture (insensitive 3-7 days)
- RNA detection/PCR (insensitive)
- West Nile virus protein can be identified in
brain specimens by immunohistochemical staining
(IHC)
25Diagnosis
- IgM Antibody-Capture Enzyme-Linked ImmunoSorbent
Assay, (MAC-ELISA 24-36 hrs) - IgM in cerebrospinal fluid confirmatory
- IgM in serum not specific
- IgG (PFNR assay) acute convalescent serum
26Outcomes
- Case-fatality rates (hospitalized)
- 4 Romania,
- 12 New York,
- 14 Israel,
- Similar (12) among Northeast US patients
2000/2001, and IL patients 2002 - lt50 of hospital patients return to functional
level by discharge only 1/3 fully ambulatory
27Outcome 1 Year Later
- Fatigue, 67
- Memory loss, 50
- Walking difficulties, 49
- Muscle weakness, 44
- Depression, 38
28Treatment of WNV Encephalitis
- Supportive hospitalization, fluids, respiratory
support, and prevention of secondary infections - Therapeutic Ribavirin Interferon ?2b have
activity against WNV in vitro - No controlled studies of these or other
medications (steroids, immune globulin) - Vaccines a few years off?
- An ounce of prevention . . .
29 1975
1975
Lyme disease first recognized Jimmy Hoffa
disappeared Movie Jaws Song Feelings
30St. Louis Encephalitis, 1975 Background
- Illinois
- 1964 Southern IL (Hamilton County)
- 1968 Saline County
- Then no activity until 1974.
- Tennessee
- 1965 Memphis-Shelby County HD began annual
bleeding of birds for SLE ab testing - 1974 increased prevalence in birds noted early
summer ? intensified mosquito control - gt50 confirmed human cases followed, 5 deaths
- Other clusters Birmingham AB, and Mexico
311975 SLE Outbreak
- 2,131 documented cases (30 states D.C.)
- 578 (27 of total) in Illinois
- 67 (66) Illinois counties reported cases
- gt50 in metropolitan Chicago
- Newspaper Headlines
- Sleeping sickness kills four
- Encephalitis at epidemic stage in Cook County
- City, county crews join mosquito war
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342001 Déjà vu all over again.
- 2001 Illinois dead bird WNV surveillance 8/02 -
10/02 - Crows, blue jays, raptors
- 138/284 (49) tested positive
- Culex mosquito pools tested in Cook County
- 20/81 pools positive
- Horses - 2 positive of 9 symptomatic
35Preliminary Positive WNV Test Results,
Illinois,2002
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37Differences Between SLE and WNV
- WNV better adapted to northern temperatures
Ontario grows 2X faster than SLE - WNV may produce higher viremia in birds
- WNV kills many birds and horses
- WNV identified in many non Culex species
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39Risk of WNV Illness
- of mosquitos X
- Prevalence in mosquitos (0.5-5) X
- of bites per mosquitos life X
- Risk that a bite transmits wnv X
- Risk of severe illness if infected (1/150)
- 1/30,000 bites??
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