0314_1030_Byrd

7/28/2019 0314_1030_Byrd

1/31

La Crosse Encephalitis in North Carolina

1Environmental Health Sciences Program

Western Carolina University

2Dept. of BiologyUNC-Greensboro

Brian Byrd 1, David Rollick 1*, Mike Riles 1*, Theo Tamini 2,

Laura White2*

, Alan Goggins1*

, Charles Sither 1*

, andGideon Wasserberg 2

*Undergraduate Students

7/28/2019 0314_1030_Byrd

2/31

Haddow AD and Odoi A, The incidence risk, clustering,and clinical presentation of La Crosse virus infectionsin the eastern United States, 2003-2007. PLoS One .2009 Jul 3;4(7):e6145.

7/28/2019 0314_1030_Byrd

3/31

La Crosse Encephalitis

Age Distribution (Years)

Illness is seen primarily in pediatrics

C a s e s

7/28/2019 0314_1030_Byrd

4/31

0

5

10

15

20

25

30

35

40

1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

N U M B E R O F C A S E S

La Crosse Encephalitis Cases (NC: 1988-2011)

*

* *

7/28/2019 0314_1030_Byrd

5/31

Annual Incidence per 100K

2001

2002

2003

2004

2005

2006

2007

2008

2009

2010

2011

2000

LACE Incidence(per 100,000)

7/28/2019 0314_1030_Byrd

6/31

2000 2002 2004 2006 2008 2010

0

5

1 0

1 5

2 0

2 5

Year

I n c

i d e n c e p e r

1 0 0 K

Annual Incidence per 100K (Western NC Counties )

7/28/2019 0314_1030_Byrd

7/31

Small MammalsTamias striatusSciurus carolinensis

Small Mammals

Tamias striatus Sciurus carolinensis

Mosquito Vector ( Ae. triseriatus )

Mosquito Vector ( Ae. triseriatus )

Female Mosquito

( Ae. triseriatus )

Human Host(Dead End)

Transovarial

Transmission

Infected Progeny

(Male and Female)

FemaleMosquito( Ae. triseriatus )

Male Mosquito( Ae. triseriatus )

(Virus dissemination/Transovarial transmission )

Venereal Transmission(male to uninfected female)

La Crosse Virus Cycle Adapted from Beaty and Marquardt (1996)

7/28/2019 0314_1030_Byrd

8/31

Secondary/Suspect Vectors

Gerhardt et al. First isolation of La Crosse virus from naturally

infected Aedes albopictus Emerg Infect Dis. 2001 Sep-Oct;7(5):807-11

Aedes albopictus

Sardelis et al, Laboratory transmission of La Crosse virus byOchlerotatus j. japonicus (Diptera: Culicidae). J Med Entomol.2002 Jul;39(4):635-9.

Aedes japonicus

7/28/2019 0314_1030_Byrd

9/31

TAP

Hughes MT et al. Comparative potential of Aedes triseriatus , Aedes albopictus , and Aedes aegypti (Diptera:Culicidae) to transovarially transmit La Crosse virus. J Med Entomol. 2006 Jul;43(4):757-61.

Transmission Amplification Potential

7/28/2019 0314_1030_Byrd

10/31

What Drives LACE Risk?

Human Behaviors Protective Risky

Location Regional Microscale/Microhabitat

Vector Ecology Temporal Risk Native/Invasive Species

Environment

Host Agent

7/28/2019 0314_1030_Byrd

11/31

Impact of AnthropogenicDisturbance

Goal: Investigate the role of anthropogeniceffects at the local habit scale

7/28/2019 0314_1030_Byrd

12/31

Study Design

Peridomestic Sites:Six (6) Historical LACE Case Residences

Forested Sites:Six (6) Forested Sites

7/28/2019 0314_1030_Byrd

13/31

Study Design

Peridomestic Forest

Case house

Ovitraps: 1 week sample periods twice monthly (May-Sept.)

Large Bore (Nasci) Aspiration: Every week

7/28/2019 0314_1030_Byrd

14/31

Results

Ae. japonicus

Ae. triseriatus**

Ae. albopictus

Ovitraps(n=11,773*)

(2%)

(15%)

(83%)

*93K collected/11.7K identified**Aedes triseriatus/Aedes hendersoni

Nasci(n=1,040)

Ae. japonicus(33%)

Ae. triseriatus** (50%)

Other

Ae. albopictus(8%)

7/28/2019 0314_1030_Byrd

15/31

Oviposition traps Total Number of eggs (n=93,158) 2-way ANOVA testing the effect of site and time

Mean number of eggs collected by sites per week from June12 th -October 8 th 2010

Number of wet containers per site

Number of eggs collected per number of wet containers

P= 0.001

P=0.0013, R=0.817

7/28/2019 0314_1030_Byrd

16/31

Sites EC, LD, LOC = High wet containers density level (HIGH DISTURBANCE)

Sites BF, OR, SL = Low wet containers density level (LOW DISTURBANCE)

EC, LD, LOC = Sites with High wet artificial containers density levelBF, OR, SL = Sites with low wet artificial containers density level

7/28/2019 0314_1030_Byrd

17/31

P = 0.03

No difference across habitat type, differences evident based on level of disturbance2-way repeated measures ANOVA testing the effect of habitat type and disturbance for each species

Does the effect of habitat type differ between sites of low disturbanceversus sites of high disturbance?

7/28/2019 0314_1030_Byrd

18/31

Does the effect of habitat type differ between sites of low disturbanceversus sites of high disturbance?

Adult (resting) mosquitoes

7/28/2019 0314_1030_Byrd

19/31

Epidemiologically Important Mosquitoes: Blood Fed and Gravid

Habitat Type Influences: Does the effect of habitat type differ between sites

of low disturbance versus high disturbance?

7/28/2019 0314_1030_Byrd

20/31

Pilot Study Conclusions

Anthropogenic effects on the LACV systems are likelymediated via the introduction of artificial containers

Artificial containers attract the sylvatic Ae. triseriatusfrom forested habitat into the peridomestic habitat?

Anthropogenic effects (artificial containers) increase Ae. japonicus oviposition in the peridomestic habitat

7/28/2019 0314_1030_Byrd

21/31

Public Health Implications

Source Reduction!

7/28/2019 0314_1030_Byrd

22/31

Vertical Distribution Studies (2011)

Trap were placed at heights of 0, 3, 6, and 9 meters

7/28/2019 0314_1030_Byrd

23/31

Results: Total Eggs Collected2791

974

2755

33

Rainfall (inches)

7/28/2019 0314_1030_Byrd

24/31

Relative Abundance

6,553 COLLECTED2,686 IDENTIFIED

Aedes triseriatus

Aedes hendersoni

Aedes japonicus Aedes albopictus

Ae. albopictus (43%)

Ae. triseriatus (24%)

Ae. japonicus (20%)

Ae. hendersoni (13%)

7/28/2019 0314_1030_Byrd

25/31

Aedes triseriatus vs Aedes hendersoni

Aedes triseriatus: 75% of the total eggs identified were oviposited at 3 or 6 meters Aedes hendersoni: 67% of the total eggs identified were oviposited at 6 or 9 meters

Aedes triseriatus Aedes hendersoni

75% 67%

N=349N=645

7/28/2019 0314_1030_Byrd

26/31

Aedes albopictus

Aedes albopictus: 74% of the total eggs were oviposited at 3 meters or below

74%

N=1,155

7/28/2019 0314_1030_Byrd

27/31

Aedes japonicus

Aedes japonicus: 61% of the total eggs identified were oviposited at ground level

61%

N=537

7/28/2019 0314_1030_Byrd

28/31

Vertical Distribution Studies (2012: 0 vs 9 m)

A total of 11,394 eggs were collected and 2,595 were reared to 4 th instars and identified to species.

7/28/2019 0314_1030_Byrd

29/31

2012 Vertical Distribution Study: A Comparative Approach (0 and 9 meters)

A

89%

11%

Natives: 349Invasive: 37



June 2012 Oviposition:

B C

64%

36%

90%

10%

7/28/2019 0314_1030_Byrd

30/31

Acknowledgements

WCU QEP Funding WCU College of Health and Human Sciences UNC-Greensboro College of Arts and Sciences UNC-Greensboro Office of Research and

Economic Development

Tamini, Tuamami T., M.S., Does anthropogenic disturbanceaffect the ecological transmission drivers of the La Crossevirus? 2011

7/28/2019 0314_1030_Byrd

31/31

Documents

0314_1030_Byrd