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Arbovirus, 2010. May 20, 2010 Susan Stowers Greg Chrislip Jonah Long Danae Bixler. Objectives. After the call, participants should understand: Descriptive epidemiology (temporal, seasonal trends and occurrence by age, gender and location) of LAC

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arbovirus 2010

Arbovirus, 2010

May 20, 2010

Susan Stowers

Greg Chrislip

Jonah Long

Danae Bixler


After the call, participants should understand:

  • Descriptive epidemiology (temporal, seasonal trends and occurrence by age, gender and location) of LAC
  • Recent mosquito and bird data for West Nile
  • Purpose and methods for avian, mosquito and human surveillance for arbovirus in West Virginia.
  • Process for human case ascertainment and investigation
  • Process and rationale for enhanced passive surveillance for 2010
west virginia arbovirus surveillance data

West Virginia Arbovirus Surveillance Data

Susan Stowers

Zoonotic Disease Data Analyst II

2009 west nile virus summary
2009 West Nile Virus Summary
  • West Nile Virus (WNV)
  • 0 Human cases
  • Others:
    • 3 WNV positive birds (Out of 35 tested)
      • (Greenbrier, Hancock and Wetzel Counties)
    • 1 WNV positive horse (Fayette County)
2009 lacrosse encephalitis
2009 LaCrosse Encephalitis
  • 14 Human Cases
  • (10 Confirmed/4 Probable)
  • Age:
    • Range: 13 Months to 15 Years
    • Mean: 9 Years, Median: 10 Years
  • 4 Female/10 Male
2009 mosquito facts
2009 Mosquito Facts
  • 854 pools (54,267 mosquitoes) collected
  • 136 pools from five counties tested positive for West Nile Virus
    • (Cabell, Jackson, Kanawha, Ohio and Putnam)
2009 mosquito surveillance
2009 Mosquito Surveillance
  • Season was early – first positives in June
    • (normally not until July)
  • Two counties (Cabell and Ohio) contributed by doing mosquito sampling
  • La Crosse encephalitis
    • Primary arbovirus of concern in West Virginia
    • Age < 15
    • Southern counties
    • Forested areas
  • West Nile virus
    • Secondary concern
    • Lull in activity
human surveillance of arboviral diseases

Human Surveillance of Arboviral Diseases:

2010 Season Update

May 20, 2010

Jonah M. Long, MPH

Zoonotic Disease Epidemiologist

Division of Infectious Disease Epidemiology

  • Human transmission
  • Reportable conditions
  • Case definition
    • Clinical
    • Laboratory
  • Epidemiologic investigation
  • Case investigation process
purpose of human surveillance
Purpose of Human Surveillance
  • Arboviral infections continue to have significant impact upon WV residents
  • Disease can be serious for vulnerable populations and treatment is supportive
    • Prevention is key
  • Data supports public health’s interest to prevent and control human infections
what is reportable in wv
What is Reportable in WV?
  • “Arboviral infection” per 64CSR7
  • To be reported within 1 week to local health department (category IV)
  • This includes the following conditions…
arboviral infection reportable
Arboviral Infection (Reportable)
  • LaCrosse encephalitis (LACV)
  • West Nile virus (WNV)
  • Saint Louis encephalitis (SLEV)*
  • Eastern Equine encephalitis (EEEV)*
  • Western Equine encephalitis (WEEV)
  • Powassan encephalitis (POWV)
  • Venezuelan Equine encephalitis (VEEV)
  • Japanese encephalitis (JEV)
  • Tickborne encephalitis (TBEV)
  • Chickungunya virus (CHKV)

Occurs in USA and WV*

*No human SLEV cases reported since 1997

Occurs in USA, could occur in WV*

*Two WV Birds tested positive for EEEV 2002

Occurs outside the USA, but may arrive via travel…

case definition
Case Definition
  • Clinical part of case definition:
    • Neuroinvasive: Fever and at least one of the following as documented by a physician:
      • Acutely altered mental status; OR
      • Other signs of acute neurologic impairment; OR
      • Increased white blood cell count in CSF + s/s meningitis
    • Non-neuroinvasive: Fever only (via clinician or patient), with no evidence of neuroinvasive disease
case classification
Case Classification
  • Confirmed arboviral infection case:
    • Meets clinical criteria and has one of the following lab criteria:
      • Four-fold or more change in antibody titer from acute and convalescent serum specimens; OR
      • Isolation of virus; OR
      • IgM + in CSF by antibody capture EIA; OR
      • IgM + in serum by antibody-capture EIA and IgG + in same or later specimen using a confirmatory serologic test (i.e., neutralization or hemagglutination inhibition)
case classification1
Case Classification
  • Probable arboviral infection case:
    • Meets clinical criteria and has one of the following lab criteria:
      • Elevated but <2-fold change in titer of antibodies from acute and convalescent serum specimens; OR
      • IgM + in serum by antibody-capture EIA but with no confirmatory results of a test for IgG antibodies in the same or a later specimen
laboratory hieroglyphics
Laboratory Hieroglyphics
  • Lab results can be tricky to interpret
  • Labs are critical for case ascertainment
    • Specimen type
    • Test methodology used
  • Sending specimens to OLS
    • Required if positive; otherwise recommended
example 1 initial csf findings
Example 1: Initial CSF findings…

High white blood cell count in CSF indicative of meningitis, if clinical signs are also present (stiff neck, headache, etc)

example 2 initial serology
Example 2: Initial Serology…

This IFA test result is not enough to classify the case; specimen should be sent to OLS for EIA test. Alternatively, a convalescent specimen could be IFA tested (rare)

example 3 ols findings
Example 3: OLS Findings…

Based on this result, specimen type and test method, this case would considered to be PROBABLE

epidemiologic investigation
Epidemiologic Investigation
  • This part of case investigation is critical
  • Site visit is necessary
    • Visualize environment
    • GPS coordinates
      • DMS: DDD° MM' SS.S"
      • DDM: DDD° MM.MMM‘
      • DD: DDD.DDDDD°
epidemiologic investigation 2
Epidemiologic Investigation (2)
  • Collect exposure data based on the relevant incubation period (typically 5 – 15 days)
    • Travel history (imported disease?)
    • Outdoor activities
    • Environmental risk factors (standing water, etc)
  • Provide education and recommendations based on findings
additional response to case
Additional Response to Case
  • Take proactive stance
  • Consider notification of local healthcare providers
  • Consider press release
    • Template on DIDE website
  • Plug prevention messages!
  • Arbovirus surveillance is important and helps focus LOCAL interventions
  • Case definition for arbovirus consists of specific clinical and lab criteria
  • Specimens should be sent on to OLS
  • Epi investigation is a critical component
arbovirus surveillance 2010




why do we use animal surveillance
  • Animal surveillance is conducted to find the virus…before there is spill-over into the human population.
mosquito surveillance
  • Set an array of traps in areas that may have considerable West Nile activity.
  • Gravid traps would be set in the same areas every week.
  • Traps set on Mondays, mosquitoes would be collected on Tuesday, Wednesday, Thursday and Friday.
mosquito surveillance1
  • Can be tested for WNV, EEE, SLE and LAC
  • Test based on mosquito species
  • PCR
what makes a good site
What Makes A Good Site?
  • We need areas where there is water with a lot of organic matter in it.....
    • Municipal sewage treatment facilities, especially older ones
    • Sewage treatment package facilities serving mobile home parks and small communities
    • Sewage lagoons
    • Communities with large numbers of failing septic systems
    • Areas which flood easily and hold water
what if we find west nile
  • Sewage lagoons, sewage treatment package plants
    • Permitted by local health department
        • Facility may need pumped
        • Vegetation should be cleared around lagoons
    • If assistance is needed contact Regional WVDEP office.
monitor dead birds
  • Local Health is point of contact for dead bird surveillance.
  • Do you have last years test kit?
  • Don’t forget to request new transport media from OLS.
2010 bird testing
2010 Bird Testing
  • We test birds all year....January through December.
  • All wild bird species tested (no poultry)
  • Bird tested for WNV, SLE, EEE using PCR
  • Call DIDE for a testing number
    • Birds sent without a number may not be tested.
bird surveillance
  • Put on gloves and mask
  • Open the birds oral cavity and swap the inside with swab provided in the kit.
  • Place the swab into the media tube, breaking off the swab if it too long.
  • Refrigerated the swap until mailed to OLS
  • Avian Oral Swab Demonstration Video under West Nile of our website.
equine surveillance what if we find west nile
  • Tested for EEE and WNV at OLS using Mac-Elisa
  • Alert veterinarians and horse owners.
  • Horses not previously vaccinated
    • Two doses recommended 3-6 weeks apart
  • Annual booster shot before arbovirus season begins
general public
  • Make home bug tight
  • Use repellents
    • DEET
    • Picaridin
    • IR3535
    • Oil of Lemon Eucalyptus
  • Empty standing water on property
lhd mosquito surveillance
  • 8 Trapping Sites
    • 7,910 mosquitoes
    • 127 pools
    • 15 pools WNV positive
  • Pools of Ochlerotatus triseriatus WNV positive
lhd mosquito surveillance1
  • 11 Trapping Sites
    • 3,896 mosquitoes
    • 122 pools
    • 21 pools WNV positive
    • Pools of Ochlerotatus japonicus WNV positive
lhd mosquito surveillance2


  • Collections from Cabell and Ohio County health departments greatly supplemented state efforts, and demonstrated that local health departments can add to state efforts.
enhanced passive surveillance 2010
Enhanced Passive Surveillance, 2010
  • Season kick-off e-mail alert, May 3
    • Local health departments, infection preventionists, laboratorians
  • Laboratory letter, May 10
    • Laboratorians
  • Health alert, May 17
    • Physicians
resources 1
Resources (1)
  • DIDE
    • => A-Z index =>
      • Arboviral encephalitis
        • Information sheets
        • Model press release
      • West Nile encephalitis
        • Dead bird specimen collection video
        • Surveillance data
      • LaCrosse encephalitis
        • Information sheets
    • (800)-423-1271
  • Office of Laboratory Services
    • (304)-558-3530
resources 2
Resources (2)
  • Entomologist
    • Mosquito complaints?
      • 800-423-1271
    • Surveillance?
      • 304-558-3530 … Ask for Greg
  • CDC
  • CEUs