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What can Vector Diagnostics do for the Deployed Entomologist?

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Title: What can Vector Diagnostics do for the Deployed Entomologist?


1
What can Vector Diagnostics do for the Deployed
Entomologist?
LTC Russell E. Coleman, Ph.D. Director,
Entomology Division Walter Reed Army Institute of
Research
Opinions, interpretations, conclusions,
recommendations are those of the author and are
not necessarily endorsed by the U.S. Army.
2
Agenda
  • What are Vector Diagnostics?
  • What do results tell us?
  • Example where vector diagnostics were used
    operationally
  • Concept of Operations
  • Development, fielding and sustainment of vector
    diagnostics

3
What are Vector Diagnostics?
  • Key Tasks of Deployed Entomologists
  • Surveillance (Collect arthropods)
  • Identification (Determine whats there)

Risk Assessment
Diagnostics (Test for pathogens)
4
What are Vector Diagnostics?
  • Any method of determining if an arthropod is
    infected with a militarily-relevant pathogen.
  • Examples
  • Dissection/Visual Examination Check midguts for
    oocysts or salivary glands for sporozoites
    (Cheap, low-throughput, time-consuming, high
    level of training, good quality microscopes
    required)
  • ELISA Test head/thorax and abdomens for
    Plasmodium circumsporozoite protein (Medium cost,
    high-throughput, High-level of training, various
    equipment, cold-chain)
  • Malaria VecTEST Assay (Medium cost,
    medium-throughput, low level of training, simple,
    no cold-chain)
  • Standard PCR (Medium/High cost,
    medium-throughput, high level of training,
    complicated, cold-chain)
  • Real-time PCR (High cost, medium-throughput,
    high level of training, simpler, cold-chain)

5
Manual Dissection of Mosquitoes
Prototype Leishmania Assay
Malaria Dipstick Assay
Real-time PCR in Iraq
6
What do results tell us?
  • Negative Results Minimal information! Tells us
    pathogen was not present in samples tested
    however, does not necessarily mean pathogen is
    not present in area. Issues
  • Sample size (100 mosquitoes tested versus 10,000
    tested)
  • Limited collection sites (may have missed key
    sites)
  • Limited collection dates (a week or two later
    pathogen present)
  • Positive Results Much more useful! Tells us
    pathogen present, but not necessarily whether
    soldiers are at risk (incompetent vectors,
    non-man biters, etc.)

7
How can results be used?
  • Negative Results Not much use
  • Positive Results Extremely useful!!!
  • Identify high-risk areas
  • Allow for prioritization of control/education
    efforts
  • High impact when requesting support
  • Increases probability that CDR/1SG will enact
    PVNTMED recommendations

8
Operational Use of Vector Diagnostics
  • Leishmaniasis (Tallil Air-Base, Iraq)
  • Base Occupied 22 Mar 03
  • First sand fly collected 7 Apr 03
  • First positive sand fly 22 Apr 04
  • Immediately Implemented Prevention and Control
    Program
  • Immediately Implemented Education Program
  • Immediate High-Visibility with Senior Command
  • First human case not detected for gt4 months
  • Malaria (Tallil Air-Base, Iraq)
  • All troops on malaria chemoprophylaxis
  • Vector surveillance revealed low numbers of
    anophelines (not sufficient to discontinue
    chemoprophylaxis)
  • Vector diagnostics revealed all anophelines
    uninfected (resulted in discontinuance of
    chemoprophylaxis)

9
Concept of Operations
  • Hand-Held Assays
  • User PVNTMED Tech (91S), Entomologist, ESO
  • Unit PVNTMED Det, BCT PVNTMED Section
  • Purpose Screening Assay
  • U/I 5/Ento Collecting Kit or As Needed
  • Reporting of Results ??? (CHPPM, Command
    Surgeon/PVNTMED)
  • Issues Cost to procure
  • Real-Time PCR Assays
  • User Microbiologist, Laboratory Technician (91K)
  • Unit AML, FDPMU, AF BAT
  • Purpose Confirmatory Assay
  • U/I JBAIDS/RAPID assigned to unit, assays
    procured as required
  • Reporting of Results ??? (PVNTMED Units, Command
    Surgeon)
  • Issues Getting samples to unit

10
Status of Vector Diagnostics
  • Hand-Held Assays
  • Malaria VecTEST Assay (Pf, PV-210, PV-247)
    Re-established, NSN recommendation, soon
    available thru VecTOR Test Systems
  • West Nile VecTEST Assay (WEE, WEE/SLE,
    WEE/SLE/EEE) NSN, available thru Fisher
    Scientific
  • Leishmania VecTEST Assay Under development
    (Phase II SBIR)
  • Dengue VecTEST Assay Ditto
  • Rift Valley Fever virus VecTEST Assay Ditto
  • Ross River virus VecTEST Assay Ditto
  • Japanese Encephalitis VecTEST Assay Ditto

11
Status of Vector Diagnostics
  • Real-time PCR Assays
  • Leishmania (Leishmania universal, L.
    major-specific, visceral-specific WRAIR and
    AFIOH)
  • Dengue universal (AFIOH)
  • USAMRIID virus assays (RVF, Dengue, JE.)
  • Various other research-grade assay that have been
    published

12
Development, Sustainment Fielding Issues
  • Development
  • Hand-Held Assays Only one company working on
    these. Funded through SBIR program
  • Real-time PCR Assays Majority of work at
    USAMRIID. Need to investigate transition of
    assays onto JBAIDS platform
  • Sustainment
  • Hand-Held Assays Commercial product with small
    market
  • Real-time PCR Assays Once assays transitioned
    to JBAIDS, enter assays into CRP (Critical
    Reagents Repository)
  • Fielding
  • Hand-Held Assays Cost, Basis of issue
  • Real-time PCR Assays Validate need for vector
    assays with JBAIDS program

13
?
Navy
Army
Air Force
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