West Nile Virus Information for the Health Care Professional

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West Nile VirusInformation for the Health Care
Professional

• Mississippi State Department of Health 2/24/2003

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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

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History of West Nile VirusOrigin

• The first case of West Nile virus was from a
  woman in the West Nile Region of Uganda, Africa
  in 1937

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Watch it Spread..

• 1999 to 2002

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Its even crossed over into Canada and Mexico
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Manit.
Saskat.
Quebec
Ontario
Nova Scotia
Ontario
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Human WNME (1 case), 2001
Equine WNME (lt5 cases), 2002
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West Nile Virus Approximate Worldwide Geographic
Range
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TransmissionHow is it Spread?
Primarily maintained in a bird-mosquito cycle.
but can spill over to other animals
including humans and horses
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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

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Theres 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
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Signs SymptomsIncubation Period
Signs and Symptoms MAY develop 3-15 days after
being bitten by an infected mosquito
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Signs SymptomsPresentations

• Most are asymptomatic (80)
• Ill patients may present with a spectrum of mild
  (20) to severe (lt1) illness
• Neurologic illness is often present with severe
  cases, or may present as its own entity

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Signs SymptomsPresentations

• 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

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Signs SymptomsMild Illness

• Self-limiting
• Mild cases may include
• Fever
• Headache
• Body aches
• Rash
• Swollen lymph nodes
• Gastrointestinal (nausea, vomiting)

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Signs SymptomsSevere 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

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Signs SymptomsSevere Illness

• Sudden onset of
• High fever
• Headache
• Confusion
• Disorientation
• Tremors
• Occasional seizures

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Signs SymptomsSevere 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

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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

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Diagnostic Findings

• CTs
• No evidence of acute disease
• MRIs
• Enhancement of leptomeninges and or
  periventricular areas seen in 1/3 of patients

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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

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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 (lt 7 days) in the
  course of illness may yield false negative
  results

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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

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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 8 C
• CSF
• Can be held at 2 8 C

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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 NEGATIVE
• May consider retesting depending on
  collection date

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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

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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

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Laboratory Testing

• Testing free of charge by the MSDH-Public Health
  Lab
• [phone] 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

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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

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Outcome of WNV Patients Mississippi 2002

• Discharged to Percent
• Died 6.2
• Home 59.6
• Nursing home 3.4
• Never 28.1
• hospitalized
• Rehab 1.7
• Unknown 6.4

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WNV Patients Mississippi 2002

• Most patients presented with meningoencephalitis
  (ME)
• Asymptomatic persons and most patients with mild
  illness do not seek medical care
• Presentation Percent
• WN Fever 16
• ME 84

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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

• Percent
• Stiff neck 29.8
• Rash 25.0
• Joint pain 24.5
• Lethargy 24.6
• Lymphadenopathy 3.7
• Seizures 2.1

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WNV Patients Physical and
Cognitive Impairments

• Frequency of physical and cognitive complaints
  before and after WNV illness (n84)
  (n84)
• COMPLAINT PRE POST
• Muscle Weakness 4.2 56
• Difficulty walking 14.4 50.6
• Fatigue 28 65.5
• General malaise 21.5 48.8
• Confusion 9.6 27.4

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West Nile VirusPrevention
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Prevention
Mosquitoes can develop in any standing water that
lasts more than 4 days
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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

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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

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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

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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

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PreventionPersonal 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

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PreventionPersonal 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

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PreventionPersonal protection

• Consider use of mosquito repellents. Carefully
  read and follow all label instructions
• Repellents containing 10 to 35 DEET for adults

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Children and Insect Repellents

• Keep repellents out of reach of children
• Dont 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

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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

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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

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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