Arbovirus, 2010

May 20, 2010Susan StowersGreg ChrislipJonah Long

Danae Bixler1

Objectives

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

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West Virginia Arbovirus Surveillance Data

Susan StowersZoonotic Disease Data Analyst II

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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)

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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

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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)

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2009 Mosquito Surveillance

Season was early – first positives in June (normally not until July)

Two counties (Cabell and Ohio) contributed by doing mosquito sampling

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Conclusions

La Crosse encephalitis Primary arbovirus of concern in West Virginia Age < 15 Southern counties Forested areas

West Nile virus Secondary concern Lull in activity

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Human Surveillance of Human Surveillance of Arboviral Diseases:Arboviral Diseases:

2010 Season Update

Jonah M. Long, MPHZoonotic Disease Epidemiologist

Division of Infectious Disease Epidemiology

May 20, 2010

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OverviewOverviewHuman transmissionReportable conditionsCase definition

◦Clinical◦Laboratory

Epidemiologic investigationCase investigation process

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West Nile Virus Transmission West Nile Virus Transmission CycleCycle

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La Crosse Virus Transmission La Crosse Virus Transmission CycleCycle

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Purpose of Human Purpose of Human SurveillanceSurveillanceArboviral 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

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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…

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Arboviral Infection Arboviral Infection (Reportable)(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…

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Case DefinitionCase DefinitionClinical 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

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Case ClassificationCase ClassificationConfirmed 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)

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Case ClassificationCase ClassificationProbable 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

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Laboratory HieroglyphicsLaboratory HieroglyphicsLab 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

recommended24

Example 1: Initial CSF Example 1: Initial CSF findings…findings…

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

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Example 2: Initial Example 2: Initial Serology…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)

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Example 3: OLS Example 3: OLS Findings…Findings…

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

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

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Epidemiologic Epidemiologic Investigation 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°

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Epidemiologic Epidemiologic Investigation (2)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

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Additional Response to Additional Response to CaseCaseTake proactive stance

Consider notification of local healthcare providers

Consider press release◦Template on DIDE website

Plug prevention messages!

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Arboviral Case Investigation Arboviral Case Investigation ProcessProcess

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ConclusionConclusionArbovirus 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

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GREG CHRISLIP

PUBLIC HEALTH ENTOMOLOGIST

ARBOVIRUS SURVEILLANCE 2010

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WHY DO WE USE ANIMAL SURVEILLANCE?

Animal surveillance is conducted to find the virus…before there is spill-over into the human population.

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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.

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MOSQUITO SURVEILLANCE

Can be tested for WNV, EEE, SLE and LAC

Test based on mosquito speciesPCR

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What Makes A Good Site?

We need areas where there is water with a lot of organic matter in it.....o Municipal sewage treatment facilities, especially older

oneso Sewage treatment package facilities serving mobile home

parks and small communitieso Sewage lagoonso Communities with large numbers of failing septic systemso Areas which flood easily and hold water

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WHAT IF WE FIND WEST NILE?

Sewage lagoons, sewage treatment package plants Permitted by local health department

FIRST CONTACT PERMIT HOLDER! Facility may need pumped Vegetation should be cleared around lagoons

WVDEP –MANAGES WASTE WATER If assistance is needed contact Regional WVDEP office.

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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.

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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.

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BIRD SURVEILLANCE

Put on gloves and maskOpen 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.

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EQUINE SURVEILLANCEWHAT 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

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GENERAL PUBLIC

Make home bug tightUse repellents

DEET Picaridin IR3535 Oil of Lemon Eucalyptus

Empty standing water on property

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LHD MOSQUITO SURVEILLANCE

CABELL-HUNTINGTON8 Trapping Sites

7,910 mosquitoes 127 pools 15 pools WNV positive

Pools of Ochlerotatus triseriatus WNV positive

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LHD MOSQUITO SURVEILLANCE

WHEELING-OHIO11 Trapping Sites

3,896 mosquitoes 122 pools 21 pools WNV positive

Pools of Ochlerotatus japonicus WNV positive

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LHD MOSQUITO SURVEILLANCE

Collections from Cabell and Ohio County health departments greatly supplemented state efforts, and demonstrated that local health departments can add to state efforts.

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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

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Resources (1)• DIDE

– www.wvidep.org => 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

– http://www.wvdhhr.org/labservices – (304)-558-3530

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Resources (2)

• Entomologist– Mosquito complaints?

• 800-423-1271

– Surveillance?• 304-558-3530 … Ask for Greg

• CDC– http://www.cdc.gov/ncidod/dvbid/arbor/index.htm

• CEUs– https://wv.train.org

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