What can Vector Diagnostics do for the Deployed Entomologist

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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.
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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

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What are Vector Diagnostics?

• Key Tasks of Deployed Entomologists
• Surveillance (Collect arthropods)
• Identification (Determine whats there)

Risk Assessment
Diagnostics (Test for pathogens)
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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)

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Manual Dissection of Mosquitoes
Prototype Leishmania Assay
Malaria Dipstick Assay
Real-time PCR in Iraq
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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.)

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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

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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)

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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

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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

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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

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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

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