Norfolk Department of Public Health Laboratory

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Arboviral Surveillance in Southeastern Virginia
Norfolk Department of Public Health
Laboratory Tidewater Regional Arboviral
Surveillance Team (TRAST)
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Testing Target

• Sentinel Chicken Serum
• Mosquito pools

For West Nile Virus (WNV) and Eastern Equine
Encephalitis Virus (EEEV)
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Testing Methods

• Molecular Diagnostics/Diagnostic Virology Using
  Real Time RT-PCR
• Mosquito Lysates
• Cell Culture Inoculation Viral Isolation

• Serological Diagnostics of Sentinel Chickens
  Using ELISA
• Brachial Blood Samples

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MOSQUITO POOLS PROCESSING ALGORITHM
Generate Lysate

MP
MP

MP POS
MP POS
CONFIRMATION
CONFIRMATION
REPORT
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Distribution of Mosquito Species Tested in the
NDPH Laboratory from 2000 - 2007
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Positive Mosquito Pools Breakdown for Mosquito
Species Tested in the NDPH Laboratory from 2000 -
2007

• EEE Virus
• Cs. melanura 337 (94.9)
• Cx. salinarius 3 (0.8)
• Ae. vexans 3 (0.8)
• Cq. perturbans 3 (0.8)
• An. crucians 2 (0.6)
• Oc. atlanticus 2 (0.6)
• Cx. pipiens 2 (0.6)
• Oc. taeniorhynchus 1 (0.3)
• Cx. restuans 1 (0.3)
• Cx. erraticus 1 (0.3)

• West Nile Virus
• Cx. pipiens 49 (46.7)
• Cs. melanura 38 (36.2)
• Cx. restuans 4 (3.8)
• Ae. albopictus 3 (2.9)
• Cx. salinarius 3 (2.9)
• Cx. spp 3 (2.9)
• Ae. vexans 1 (0.9)
• An. quadrimaculatus 1 (0.9)
• Cq. perturbans_at_ 1 (0.9)
• Cx. erraticus 1 (0.9)
• Oc. taeniorhyncus 1 (0.9)

_at_ First reported WNV positive mosquito species in
Virginia, 2005.
First reported EEE positive mosquito species in
Virginia, 2006.
First reported WNV mosquito species in Hampton
Roads, 2006.
First reported EEE mosquito species in Hampton
Roads, 2007.
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History of WNV Positive Mosquito Pools
Distribution During Epi Weeks in the Tidewater
Area, 2006-2007
Positive Mosquito Pools
Epi Week
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History of EEEV Positive Mosquito Pools
Distribution During Epi Weeks in the Tidewater
Area, 2006-2007
Positive Mosquito Pools
Epi Week
9

Seasonal Trend of WNV and EEEV Positive Mosquito
Pools, 2000-2007
WNV
Number of positive mosquito pools
EEEV
Month
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• Serological Diagnostics of Sentinel Chickens
  Using ELISA
• Brachial Blood Samples
• Dried Blood Spot

AntiArbovirus-specific Conjugate with
horseradish peroxidase
Arbovirus-specific Antigen
Chicken IgM (If present in serum sample)
Anti-Chicken Immunoglobulin
Chicken IgA (If present in serum sample)
Chicken IgG (If present in serum sample)
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Seasonal Trend of WNV and EEEV IgM in Sentinel
Chickens, 2000-2007

WNV
Number of Seroconverted Chickens
EEEV
Month
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WNV and EEEV Immunoglobulins Results for Sentinel
Chicken Sera in 2005 and 2006
Number of chickens showing positive for EEEV
antibody ()
Description of samples
2006
2005
IgM IgA IgG IgM IgA IgG- IgM IgA- IgG- IgM-
IgA IgG IgM- IgA IgG- IgM IgA- IgG IgM- IgA-
IgG IgM- IgA- IgG-
30 (23.6) 4 (3.1) 47 (37.0) 0 2
(1.6) 3 (2.4) 1 (0.8) 40 (31.5)
11 (13.9) 1 (1.3) 4 (5.1) 0 3 (3.8) 0
4 (5.1) 56 (70.9)
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WNV and EEEV Seroconverted Sentinel Chickens and
Mosquito Pools Positives in the Tidewater Area,
2000-2007
Positive Sentinel Chickens
Positive Mosquito Pools
Year
EEEV
WNV
WNV
EEEV
2007 2006 2005 2004 2003 2002 2001 2000
3 15 21 23 28 10 1 0
21 57 143 52 42 3 28 7
0 4 6 28 30 6 0 0
17 16 87 15 17 1 0 0
153
74
353
101
Total
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Summary
Cs. melanura is the highest (94.9) for EEEV
infections among the positive mosquito species
tested
Cx. pipiens (46.7) and Cs. melanura (36.2) are
on the top for WNV infections among the positive
mosquito species tested
In most years, peak EEEV infections for positive
pools and chicken seroconversion were generally
observed before peak infections of WNV
WNV was detected peaking in Aug.- Sep., at a time
when Cx. pipiens and Cs. melanura were most
abundant
The region has seen more EEEV positive mosquito
pools than WNV. The same is true for chicken
seroconversions
Testing IgM, IgG and IgA simultaneously would
provide a comprehensive anti-arboviral antibody
coverage
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ACKNOWLEDGEMENTS

• Norfolk Public Health Laboratory
• Chesapeake Mosquito Control Commission
• Hampton Mosquito Control
• Langley Air Force Base Mosquito Control
• Newport News Mosquito Control
• Norfolk Vector Control Division
• Portsmouth Mosquito Control
• Suffolk Mosquito Control
• Virginia Beach Mosquito Control