Mosquito Surveillance for EEE

and Other Arboviruses in CT

Philip Armstrong

Department of Environmental Sciences

Center for Vector Biology & Zoonotic Diseases

The Connecticut Agricultural Experiment Station

New Haven, CT

Connecticut Mosquito Management Program

• Established 1997 by Public Act 97-289

• Comprised of 5 State Agencies

• The CT Agricultural Experiment Station (mosquito surveillance, virus

testing)

• Department of Public Health (epidemiology of human, veterinary cases)

• Department of Energy & Environmental Protection (mosquito control,

habitat restoration)

• Department of Agriculture (veterinary cases)

• Pathobiology Department at UCONN (necropsy, initial veterinary testing)

• Rural Areas

• Permanent swamps and bogs

• Marsh areas (fresh and salt)

Mosquito Trapping Locations

• Urban / Suburban Sites

• Neighborhood parks and

schools

• Along waterways and

streams

• Sewage treatment plants

• Horse stables

(92)

LitchfieldHartford

Tolland

Windham

New LondonMiddlesexNew Haven

Fairfield

WNV EEEEEE

• Mosquito trapping from June – October

• 92 permanent trapping stations (ADD 15 in 2020)

• 91 Sites maintained by CAES

• 1 Site maintained by US Navy

• Trap on a Rotational Basis (about every 10 days)

• If WNV or EEE isolates from mosquitoes

•Trap Weekly (twice if possible)

• 2 or 3 types of trap per location

Detect virus in mosquitoes prior to human or animal

cases

Mosquito Surveillance

• Host seeking females

• Out for blood

• Collects a large & diverse

number of mosquitoes

• Aedes/Ochlerotatus

• Coquillettidia

• Culex

• Culiseta

• Psorophora

CDC Light Trap

CO2

• Host seeking females

• Out for blood

• Collects a large & diverse

number of mosquitoes

• Aedes/Ochlerotatus

• Coquillettidia

• Culex

• Culiseta

• Psorophora

CDC Light Trap

CO2

• Hay-yeast-lactalbumin infusion

• Culex pipiens & Cx. restuans• Ready to lay eggs• Obtained blood meal• More Likely to be WNV (+)• 90% of collection

• Accounts for >75% of WNV (+) isolates from Cx. pipiens and Cx. restuans

CDC Gravid Trap

• Designed for Ae. albopictus• Used at sites to evaluate

population size

• Small populations in CT•Coastal Fairfield and New Haven counties

• Invasive Species

• Aggressive Human Biter• Secondary vector of Zika,

Chikungunya and Dengue

BG Sentinel Trap

scent

• Females identified to species

- 43 species collected in 2019

• Completed on day of collection

- 6 identifiers during peak season

• Pooled by species, site and trap type

- Maximum of 50 / pool

• All species tested for arboviruses

Mosquito Identification

• Biosafety Level 3 Laboratory

– Incubate for 7 days at 37oC in 5%CO2

– Examine daily for virus growth

• Virus isolation in Vero cell cultures

(African Green Monkey)

Virus Isolation & Identification

• Virus identification by

Real time PCR, RT-PCR,

molecular techniques

• West Nile Virus

• Eastern Equine Encephalitis

• Jamestown Canyon

• Cache Valley

• La Crosse

• Trivittatus

• Potosi

• Highlands J

• Flanders

• Can detect Zika, Chikungunya,

or other exotic viruses

Mosquito-Borne Viruses in Connecticut

Cause Human

Disease

Human Disease Causing Mosquito-Borne Viruses in CT

VirusNo.

isolations*

No. locations

*Reservoir Age Group Human disease

West Nile 2,440 106 Bird ElderlyModerate to severe, fever, encephalitis

Eastern Equine Encephalitis

534 48 BirdChildren, Elderly

Severe, encephalitis

Jamestown Canyon

557 88 White-tailed deer All agesFever, meningitis,

encephalitis

Cache Valley 226 71 Deer, horse, sheep All agesFever, meningitis,

encephalitis

Trivittatus 104 25Rabbit, squirrel,

raccoon, opossumAll ages Febrile illness

La Crosse 5 3 Squirrel, chipmunk Children Severe, encephalitis

* = 1997-2019

• EEE, WNV, or exotic virus identified

• Notify CT DPH, DEEP

• DPH contacts local Health Dept.

• Report to CDC (ArboNet)

• Post on CAES/Mosquito Management Website• www.portal.ct.gov/caes

• www.portal.ct.gov/mosquito

• Map

• Weekly & Cumulative Results Tables

• Press Release may be issued (state or local)

Reporting of Results

SEARCH: “CAES Mosquito Testing”

Northeastern US EEE Virus Transmission Cycle

Culiseta melanura

Virus

EnzooticCycle

Wild Passerine Bird

Reservoir and Amplifying

Hosts

JulytoOctober

Northeastern US EEE Virus Transmission Cycle

Culiseta melanura

Virus

EnzooticCycle

Wild Passerine Bird

Reservoir and Amplifying

Hosts

“Incidental”

Infections

Coquillettidia perturbans

Culiseta melanura

Aedes and

Ochlerotatus species

Epidemic / Epizootic

Transmission

JulytoOctober

August to October

Eastern Equine Encephalitis Actvivity, 1999-2017

0

50

100

150

'96 '98 '00 '02 '04 '06 '08 '10 '12 '14 '16 '18

Virus Isolations per Year

Total = 534

Eastern Equine Encephalitis Activity, 1996-2019

0

40

80

120

7/1 7/8 7/15 7/22 7/29 8/5 8/12 8/19 8/24 9/2 9/9 9/16 9/23 9/30 10/7 10/14 10/21 10/28

No

. E

EE

vir

us

is

ola

tio

ns

Week

1996-2018

2013

Weekly Isolations of EEE virus

from field collected mosquitoes

in Connecticut

0

10

20

30

40

506

/2-6

/8

6/9

-6/1

5

6/1

6-6

/22

6/2

3-6

/29

6/3

0-7

/6

7/7

-7/1

3

7/1

4-7

/20

7/2

1-7

/27

7/2

8-8

/3

8/4

-8/1

0

8/1

1-8

/17

8/1

8-8

/24

8/2

5-8

/31

9/1

-9/7

9/8

-9/1

4

9/1

5-9

/21

9/2

2-9

/28

9/2

9-1

0/5

10

/6-1

0/1

2

10

/13

-10

/19

10

/20

-10

/26

10

/28

-11

/3

EEE

Iso

late

s p

er

We

ek

2019 Eastern Equine Encephalitis Activity per WeekNon-mammalian biter (n=90)

Mammalian biter (n=32)= Human Case* (n=4) = Horse Case* (n=6) = Pheasant or Partridge* (n=2)

* = onset of illness symptoms

EEE Isolations from Mosquito Pools - CT 1996-2019

Cs. melanura63%

Oc. canadensis7%

Ae. cinereus4%

Ae. vexans3%

Cx. salinarius3%

Ur. sapphirina3%

Cx. pipiens2%

Other Species

11%

Cs. melanura

2%

Species Isolates

Culiseta melanura 344

Ochlerotatus canadensis 37

Aedes cinereus 20

Aedes vexans 19

Uranotaenia sapphirina 19

Culex salinarius 16

Coquillettidia perturbans 10

Culex pipiens 10

Other Species (11) 58

TOTAL 534

Culex pipiens

Culex restuans

Culiseta melanura

Wild Passerine Bird Reservoir

and Amplifying Hosts

Virus

EnzooticCycle

JunetoOctober

Northeastern US West Nile Virus Transmission Cycle

Northeastern US West Nile Virus Transmission Cycle

Culex pipiens

Culex restuans

Culiseta melanura

Wild Passerine Bird Reservoir

and Amplifying Hosts

Virus

EnzooticCycle

“Incidental”

Infections

Culex salinarius

Culex pipiens

Aedes vexans

Epidemic / Epizootic

Transmission

July to October

JunetoOctober

West Nile Virus Isolates from Mosquitoes, 1999-2019

0

100

200

300

400

'99 '01 '03 '05 '07 '09 '11 '13 '15 '17 '19

Virus Isolations per Year

Total = 2.440

West Nile Virus Human Infections, 1999-2019

0

10

20

30

'99 '01 '03 '05 '07 '09 '11 '13 '15 '17 '19

Human Infections per Year

Total = 158

WNV Isolations from Mosquito Pools, CT 1999-2019

Culex pipiens69%

Culex restuans

14%

Culex salinarius

7%

Culiseta melanura

5%

Species Isolates

Culex pipiens 1,695

Culex restuans 341

Culex salinarius 171

Culiseta melanura 118

Aedes vexans 19

Aedes cinereus 13

Coquillettidia perturbans 14

Ochlerotatus japonicus 10

Oc. canadensis 12

Oc. taeniorhynchus 6

Other Species (14) 52

TOTAL 2,440

Other species (19) 5%

0

0.5

1

1.5

2

0

5

10

15

20

25

6/1 6/8 6/15 6/22 6/29 7/6 7/13 7/20 7/27 8/3 8/10 8/17 8/24 8/31 9/7 9/14 9/21 9/28 10/5 10/12 10/19 10/26

No

. W

NV

Is

ola

tes

Week

10 yr Mean Human

10 yr Mean Mosq.

WNV Epidemic Curve

Jamestown Canyon Virus

Human Case – CT, 2018• Meningitis

• Bethlehem (Litchfield County)

• Onset of Symptoms on September 4th

• 1st CT case documented since 2001

Human Symptoms• Mild

• Flu-like

• Fever, headache, fatigue

• Severe

• Meningitis, encephalitis

• All ages affected

Neurological illness in humans is rare• 4-10% of the CT residents have antibody to the virus

• About ~1 case/year reported in US prior to 2013

• 181 human cases reported 2013-2018

• Neuroivasive cases in Northeast (CT, MA, ME, NH, NJ, NY, RI)c

Jamestown Canyon Virus

• 23 Virus Isolations – CT, 2019• 15 sites in 15 towns

• June 4th – September 9th

• 9 species

• Enzootic Cycle between deer and

mammal-biting mosquitoes• Wide-spread distribution in CT (88 sites)

• 557 isolates (1997-2019)

• Higher prevalence in June & July

• 25 species

• “Snow-pool” Ochlerotaus, Aedes species

Weekly Jamestown Canyon Virus Isolations from Mosquitoes

Jun Jul Aug Sept

No

. viru

s iso

latio

ns

0

5

10

15

20

25

30

35

40

45

Me

an

no

. m

osq

uito

es / lig

ht tr

ap

0

40

80

120

160

200

240

280

Virus isolations

Mosquitoes

0.03

0.19

0.37

0.39

0.12

0.25

0.13

0.22

0.20

0.060.05

0.10

0.030.09

0.07

MLE = 0.03 - 0.39

The Connecticut Agricultural Experiment Station

Mosquito Collection and Identification

John Shepard

Tanya Petruff

Virus Isolation and Identification (BSL-3)Angela Bransfield

Michael Misencik

Station Director

Dr. Theodore Andreadis

CT Department of Public Health

Dr. Matthew Cartter

Dr. Jocelyn Mullins

Brenda Esponda-Morrison

CT Dept. of Energy & Environmental Protection

Roger Wolfe

Steve Rosa

Acknowledgements

Seasonal StaffCatherine Cleary Noelle Khalil

Caroline Cullen Alyssa Marini

Will Cutrone Joey Miller

Andrew Donnellycolt Anthony Perugini

Patrick Daly Mike Olson

Ron Ferrucci Demi Rodriguez

Aiden Florio Bill Sennett

Joshua Stumpf

CT Department of Agriculture

Dr. Mary Jane Lis

U.S. Navy, Groton Sub Base

HM3 Ervin Jimenez

HM3 Hunter Baughman

HM1 James Limer

Questions?

Philip Armstrong

Connecticut Mosquito and Arbovirus Surveillance Program

The Connecticut Agricultural Experiment Station

New Haven, CT

Philip.Armstrong@ct.gov

203-974-8510

Mosquito Surveillance: www.portal.ct.gov/caes

Mosquito Management Program: www.portal.ct.gov/mosquito