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West Nile Virus Information for the Health Care Professional

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West Nile Virus
Information for the Health Care Professional
Mississippi State Department of Health
2/24/2003
2/26/03 SAS
What Is West Nile Virus?
• Arbovirus (arthropod-borne virus) that can cause
infection/inflammation of spinal cord and or brain
• Illness can occur in
– Birds
– Humans
– Horses
• Transmitted by mosquitoes, and rarely by blood
transfusion, organ transplant, transplacental, or
breast milk
• It has not been shown to be transmitted
through contact with an infected bird,
human, or horse but is theoretically possible
2/26/03 SAS
History of West Nile Virus:
Origin
The first case of
West Nile virus
was from a
woman in the
West Nile
Region of
Uganda, Africa
in 1937
2/26/03 SAS
Watch it Spread…..
1999 to 2002
2/26/03 SAS
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It’s even crossed over into
Canada and Mexico…
2/26/03 SAS
Saskat. Manit.
Ontario
Quebec
Nova
Scotia
Ontario
2/26/03 SAS
Human WNME (1 case), 2001
Equine WNME (<5 cases), 2002
West Nile Virus:
Approximate Worldwide Geographic Range
2/26/03 SAS
Transmission
How is it Spread?
Primarily maintained in a birdmosquito cycle….
…but can spill over to other animals
including humans and horses
2/26/03 SAS
Arbovirus Surveillance
Mississippi Activities
To identify WNV activity, the MSDH
routinely performs the following
activities:
• Dead Bird Report Surveillance
• Dead Bird Testing
• Horse Testing
• Mosquito Collection and Testing
• Human Testing
2/26/03 SAS
“There’s a dead bird in my yard!!”
The Public is encouraged to report all dead
birds to their local health department or the
WNV hot line:
1-877-WST-NILE
2/26/03 SAS
Signs & Symptoms:
Incubation Period
Signs and Symptoms MAY
develop 3-15 days after
being bitten by an infected
mosquito
2/26/03 SAS
Signs & Symptoms:
Presentations
• Most are asymptomatic (80%)
• Ill patients may present with a
spectrum of mild (20%) to severe
(<1%) illness
• Neurologic illness is often present
with severe cases, or may present as
it’s own entity
2/26/03 SAS
Signs & Symptoms:
Presentations
• Mild Illness (WN Fever)
– usually does not progress to severe
illness
• Severe Illness (meningoencephalitis)
– May present with neurologic component
• Muscle Weakness or Paralysis
– May present only with muscle weakness
or paralysis or stroke-like symptoms
2/26/03 SAS
Signs & Symptoms:
Mild Illness
• Self-limiting
• Mild cases may include:
– Fever
– Headache
– Body aches
– Rash
– Swollen lymph nodes
– Gastrointestinal (nausea, vomiting)
2/26/03 SAS
Signs & Symptoms:
Severe Illness
• Encephalitis – Inflammation of
the brain
• Meningitis - Inflammation of the
lining of the brain or spinal
cord
• Muscle Weakness / Paralysis or
other neurologic problem Acute flaccid paralysis,
tremors, myoclonus
2/26/03 SAS
Signs & Symptoms:
Severe Illness
Sudden onset of:
•
•
•
•
•
•
2/26/03 SAS
High fever
Headache
Confusion
Disorientation
Tremors
Occasional seizures
Signs & Symptoms:
Severe Illness
Other symptoms
•
•
•
•
•
Muscle weakness
Paralysis
Altered reflexes
Stupor
Tremors
May result in
• Coma
• Death
The Elderly are at greater
risk for more severe illness
2/26/03 SAS
Laboratory Findings
• CBC
– WBC normal or elevated
– Lymphocytopenia may occur
– Anemia may occur
• Chemistry
– Hyponatremia sometimes present, particularly
among patients with encephalitis
• CSF
– Pleocytosis
– Protein elevated
– Glucose normal
2/26/03 SAS
Diagnostic Findings
• CT’s
– No evidence of acute disease
• MRI’s
– Enhancement of leptomeninges and or
periventricular areas seen in 1/3 of
patients
2/26/03 SAS
Laboratory Testing
• IgM MAC-ELISA (antibody capture enzyme-linked
immunosorbent assay)
– Most efficient diagnostic method
– Serum or CSF
– IgM antibody does not cross blood-brain barrier
thus IgM in CSF suggests CNS infection
• PRNT (plaque reduction neutralization)
– Confirmation test for positive serum
• PCR (polymerase chain reaction)
– Inefficient due to short duration of viremia
– Can help diagnose in immunocompromised
• CSF or tissue only
2/26/03 SAS
Laboratory Testing
• May be difficult to interpret
– IgM levels may persist for more than one year
• New infection vs old infection?
• Need clinical information
• May need convalescent sample or IgA titer for serum
samples
– Tests of a single acute-phase (serum or CSF)
specimen may be diagnostically inconclusive
– Cross reactivity between flaviviruses
• With WNV + test, may see SLE + and vice versa
• Samples collected too acute (< 7 days) in
the course of illness may yield false
negative results
2/26/03 SAS
Laboratory Testing
Collection
• Include MSDH submission form
• Serum specimen of choice because
fewer antibodies in CSF
• Ship all samples with cold packs
• Do NOT use polystyrene tubes
• Do NOT freeze specimens
2/26/03 SAS
Laboratory Testing
Collection
• Sera
– Collect in tube with gel separator
– Spin sample for shipping as free
hemoglobin may result in false positive
results
– Once separated, serum can be held at
2–8C
• CSF
– Can be held at 2 – 8 C
2/26/03 SAS
Laboratory Testing
IgM ELISA for WNV
Results from the MSDH-PHL for acute WNV
infections are interpreted as follows:
Serum
• Reactive
CASE-PROBABLE
– If also positive by PRNT CASE-CONFIRMED
• Gray Zone
SUSPECT
– Not a Case
– Requires convalescent sample and or PRNT
• Non-Reactive
2/26/03 SAS
NEGATIVE
– May consider retesting depending on
collection date
Laboratory Testing
IgM ELISA for WNV
CSF
• Reactive
CASE-CONFIRMED
– Does not require PRNT
• Gray Zone
SUSPECT
– Requires convalescent sample or PRNT
– Or consider paired sera
• Non-Reactive
NEGATIVE
– Consider re-testing depending on collection date
– Or consider paired sera
*For immune-compromised consider
PCR testing of CSF
2/26/03 SAS
Laboratory Testing
IgM ELISA for WNV
CSF or Serum
• Inconclusive
INCONCLUSIVE
– Most inconclusive results are due to
non-specific binding of patient serum
or CSF to test components
2/26/03 SAS
Laboratory Testing
• Testing free of charge by the MSDHPublic Health Lab
– (601)576-7582 or
– 1-877-WST-NILE (1-877-978-6453)
• Vaccination or infection with related
flaviviruses (e.g., yellow fever,
Japanese encephalitis, dengue) may
result in positive test
2/26/03 SAS
No specific therapy
Only supportive care for severe infections
•
•
•
•
Hospitalization
IV fluids,nutrition
Ventilator support
Prevention of secondary
infections
• Good nursing care
• Ribavirin in high doses and
interferon alpha-2b show
activity in vitro
• No clinical data yet - nor for other
meds, including steroids,
antiseizure drugs, or osmotic agents
2/26/03 SAS
Outcome of WNV Patients
Mississippi 2002
Discharged to:
Died
Home
Nursing home
Never
hospitalized
Rehab
Unknown
2/26/03 SAS
Percent
6.2%
59.6%
3.4%
28.1%
1.7%
6.4%
WNV Patients
Mississippi 2002
• Most patients presented with
meningoencephalitis (ME)
• Asymptomatic persons and most patients
with mild illness do not seek medical care
Presentation
WN Fever
ME
2/26/03 SAS
Percent
16%
84%
WNV Patients
Mississippi 2002
Signs and symptoms among MS patients:
Percent
Fever
91.5%
Headache
72.3%
Muscle Weakness 56.9%
Nausea
50.8%
Vomiting
35.8%
Muscle pain
34.6%
Altered mental
34.6%
status
2/26/03 SAS
Percent
Stiff neck
29.8%
Rash
25.0%
Joint pain
24.5%
Lethargy
24.6%
Lymphadenopathy 3.7%
Seizures
2.1%
WNV Patients
Physical and Cognitive Impairments
Frequency of physical and cognitive
complaints before and after WNV illness
(n=84)
COMPLAINT
Muscle Weakness
Difficulty walking
Fatigue
General malaise
Confusion
2/26/03 SAS
PRE
4.2%
14.4%
28%
21.5%
9.6%
(n=84)
POST
56%
50.6%
65.5%
48.8%
27.4%
West Nile Virus
Prevention
2/26/03 SAS
Prevention
Mosquitoes can develop
in any standing water
that lasts more than 4
days
2/26/03 SAS
Prevention
• Properly dispose of water-
holding containers
• Drill holes in bottom of recycling
containers kept outdoors
• Cover rain water collection
containers with window
screening to prevent female
mosquitoes from laying eggs in
the water
2/26/03 SAS
Prevention
• Make sure roof gutters
drain properly, and clean
clogged gutters in the
spring and fall
• Change water in bird baths
twice weekly
• Turn over plastic wading
pools and wheelbarrows when not in use
2/26/03 SAS
Prevention
• Clean and chlorinate
swimming pools, outdoor saunas, hot tubs
• Drain water from pool covers
• Clean vegetation and debris from the edge
of ornamental ponds
• Use landscaping to eliminate water from
your property
• Fill in potholes in driveways
2/26/03 SAS
Prevention
• Make sure all windows
and doors have
screens
• Keep all screens
repaired (fix holes and
rips)
• Repair glass in broken
windows
• Keep doors closed
2/26/03 SAS
Prevention:
Personal protection
• Minimize outdoor
activities between
dusk and dawn, many
mosquitoes are active
at these times
• However, other
mosquito species can
be active during the
late afternoon
2/26/03 SAS
Prevention:
Personal protection
Wear shoes and
socks, long pants
and a long-sleeved
shirt when outdoors
for a long period of
time, or when
mosquitoes are
more active
2/26/03 SAS
Prevention:
Personal protection
• Consider use of mosquito repellents.
Carefully read and follow all label
instructions
• Repellents containing 10 to 35% DEET for
adults
2/26/03 SAS
Children and Insect Repellents
• Keep repellents out of reach of children
• Don’t allow children to apply repellents to
themselves
• Rub repellent on skin of child; do not spray
• Use small amounts of repellent on children
and follow label instructions carefully
• Do not apply to the hands of young children
• American Academy of Pediatrics
recommends 10% DEET for children
2/26/03 SAS
Fight the Bite
MSDH Objectives
• Promote public cooperation to reduce
mosquito breeding sites
• Help individuals reduce their risk of being
bitten by mosquitoes
• Educate providers about WNV
• Enlist media to present accurate
representations of WNV
• Focus on high-risk populations
2/26/03 SAS
Fight the Bite
MSDH Objectives
Call the MSDH if you have any questions at:
• WNV Hot line
1 – 877 - WST – NILE
• Division of Epidemiology
601 – 576 – 7725
• Public Health Laboratory
601-576-7582
2/26/03 SAS
Fight the Bite
MSDH Objectives
Or visit the web site at:
www.msdh.state.ms.us
or the CDC web site at:
www.cdc.gov
2/26/03 SAS
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