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Introduction to vector-borne disease ecology;

West Nile virus update; ArboNET structure and function

Chet Moore

Environmental Health Advanced Systems Laboratory Dept. of Environmental & radiological Health Sciences

Colorado State University

Geological scale

Landscape Ecology

Community Ecology

Population Ecology

Behavior

Physiology

Cell Biology

Molecular Biology

Agriculture Health Natural Resources

EpidemiologyOrnithology

MammalogyEntomology

Botany

Microbiology

Sca

le

Organism

Application

The Balkanization of ScienceThe Balkanization of Science

VBCI

Introduction to vector-borne disease ecology;

ArboNET structure and function; West Nile virus update, 2003

Chet Moore

Environmental Health Advanced Systems Laboratory Dept. of Environmental & radiological Health Sciences

Colorado State University

Vector

n [fr. L., vectus]

2 a: an organism (as an insect) that transmits a

pathogen.Webster

Zoonosis

A disease that occurs naturally in

animals other than humans, and

often is communicable to humans.

n [Gk zo- animal + nosos disease]

H VVE

B

EH

P

The Vector-borne Disease SystemThe Vector-borne Disease System

Suitable Environment

Host

Vector

PathogenUnsuitable environment (matrix)

Arbovirus Transmission Cycle

Vertebrate Host

Vector

Adults

Larvae

Eggs

Pupae AquaticTerrestrial

Virus Virus

Dead-end hosts

Arbovirus Transmission Cycle

Vertebrate Host

Vector

Adults

Larvae

Eggs

Pupae AquaticTerrestrial

Virus Virus

Dead-end hosts

Weather and

Climate

Food, Space,

Breeding sites

Weather and

Climate

Food, Space,

Breeding sites

Predators and

Pathogens

Impact of rain on larval habitats

Impact of rain on food supply

of vertebratehost

Impact of temperature on larval growthand development

TIME

Impact of R.H. and temperature on adult survival

Impact of temperature on host and vector

winter survival

Weather and Climate Affect the System in a Complex Fashion

Today

Spring FallSummer Winter

Total females (e.g., light traps)

Infected female mosquitoes Overwintering

(diapause) females

Human cases

Infected birds

Temporal pattern of arbovirus activity: vectors, birds, and humans

ArboNET – Structure and Function

The Arbonet TeamDivision of Vector-Borne Infectious DiseasesCenters for Disease Control and Prevention

Fort Collins, Colorado

ArboNET Description

• CDC’s system for national arboviral (WNV) surveillance

• 57 state / metropolitan health depts.– 50 states and PR– NYC, DC, Philadelphia, Chicago, Houston,

Los Angeles

• Published guidelines– Case definitions / diagnostic methods

ArboNET Description: National surveillance guidelines

Funding for Surveillance

• Emerging Infections Program - CDC

– Enhanced Laboratory Capacity (ELC) program• Five year cycle

– Cooperative Agreements (renewed yearly)

• ELC and WNV funding expected to continue

Enhanced Laboratory Capacity (ELC) Funding, 1999-2004

0

5

10

15

20

25

30

35

40

Aw

ard

s (m

illi

on

s)

YearMean: $2,250,792Range: $144, 311 – $11,201, 533

Goals of national West Nile virus surveillance

• Track geographic spread in the United States

• Detect increasing virus activity before humans are at significant risk– Enable interventions and educational messages

• Characterize secular trends

• Provide basis for policy / resource allocation

ArboNET Cast of players

• State and local health departments– Collect field and clinical specimens – Conduct human epidemiologic investigations – Laboratory testing– Data entry and reporting

• Commercial laboratories– human (equine) diagnostic testing

• CDC ArboNET staff– Atlanta (server support) – to Ft. Collins, 2004

– Fort Collins• Programmers (2 Access, 1 Java, 1 XML)• ArboNET technicians (3+)• Medical epidemiologists (7)• Laboratory diagnostic reference section

(approx. 10)

ArboNET Cast of Players

2003

Peggy Collins

Arbonauts: The ArboNET TeamPage 1…

Roy Campbell

Nick Crall

Jen Brown

John Jones

Krista Kniss Stephanie KuhnJen Lehman

Tony Marfin Sue Montgomery Dan O’Leary

…Page 2!

ArboNET Cast of Players

• Other U.S. agencies– Department of Defense

• Mosquito collection and testing

– Department of Agriculture• Equine diagnostic testing

– Geological Survey• Dead bird diagnostic testing• Geospatial mapping

ArboNET Surveillance Categories

• Human– Meningitis, encephalitis, AFP (neuroinvasive)– Uncomplicated fever (non-neuroinvasive)

• Birds– Dead (wild)– Caged sentinel (chickens, pigeons)– Live-caught wild

• Non-human mammals (horses)

• Mosquitoes

ArboNet Data Flow : State Health Department to CDC

Human, mosquito, bird, horse specimens

State, Commercial, Reference Labs

DOH WNV Coordinator

Suspect Human Case Investigations

CDC Public domain

Data flow through ArboNET

• Reporting pathways (4)– ArboNET stand-alone software

• CDC-developed• MS Access-based• XML data transfer format

– Proprietary software • Commercial or locally-produced• XML data transfer format

– Secure website– Combinations

Data flow through ArboNET, 2002

• Use of reporting pathways– ArboNET (38%)

– Proprietary software (16%)

– Secure website (42%)

– Combinations (4%)

ArboNET data

• Numerator (individual)– Human disease cases

– Equine disease cases / other infected mammals

– Infected birds (dead, sentinel, live-caught wild)

– Infected mosquito pools

• Denominator (aggregated)– Total individuals tested per week and county

(avian and mosquito only)

ArboNET data

• Numerator records

(individual totals)– 2000 (5,001)– 2001 (9,324)– 2002 (44,157)– 2003 (?)

• Denominator records

(aggregate totals)– 2000 (18,881)– 2001 (42,208)– 2002 (54,375)– 2003 (?)

End-users of ArboNET data

• Participating health departments– Weekly conference call and secure internet

• USGS– Weekly data snapshot---surveillance maps

• Public– Peer reviewed publications– CDC publications (MMWR weekly updates)– Maps (via CDC and USGS websites)– Media interviews

• Senior public health officials

ArboNET data limitations

• Lag time – Delays in testing and reporting

• Data quality– Adherence to national surveillance guidelines

currently unknown• Case definitions (case misclassification)• Testing procedures (false positives & negatives)

– Variabile emphasis on respective surveillance categories

– Incomplete reporting & aggregation of denominator data

Limitations: ‘first activity’ data

• Do reporting delays permit timely interventions?

• Low specificity of animal data, 2002– 2,531 counties detected animal activity – Human cases in only 1,942 (23%)

• Modification by early public health measures?

• Human disease unrelated to animal disease?

Percent of Reported West Nile Virus Cases Classified as West Nile Fever, United States, 2003

* Reported as of 5/20/2004

0-24

25-49

50-74

Percent of Cases

75-100

Historical Perspective

Progression of West Nile Virus Activity in the United States, 1999-

2003

•Reported to ArboNET as of 5/20/2004

Year # States # Counties Date Range

19991999 44 2828 9 AUG – 15 NOV9 AUG – 15 NOV

2000 12** 145 6 FEB – 17 NOV

2001 27** 359 8 APR – 26 DEC

2002 44** 2,531 3 JAN – 19 DEC

20032003 46**46** 2,3582,358 1 JAN – 31 DEC1 JAN – 31 DEC

States and Counties Reporting WNV Activity, United States, 1999-2003*

** Plus D.C.

West Nile VirusBird Surveillance

United States, 2003

WNV Surveillance, United States, 2003*:Summary of Dead Bird Data

• 97,905 dead birds reported

• 25,339 tested (26%)

• 12,066 WNV-positive birds reported• 10,200 corvids (85%)• 1,866 birds of other spp. (15%)

(1999-2003: 229 spp. WNV-positive dead birds reported to CDC)


“Top Ten” WNV-Positive Bird Species Reported, United States, 2003*

Species # positive birds % of Total

American Crow 4,180 35

Blue Jay 3,793 31

Crow Species 1,766 15

Other Species 501 4

Black-Billed Magpie 319 3

House Sparrow 250 2

Northern Cardinal 181 2

Fish Crow 100 1

Red-tailed Hawk 96 1

Common Grackle 91 1


Timing of WNV-Positive Dead Bird Collection and Human WNV Case Onset, By County, United States, 2003*


Counties Reporting Bird and Human Surveillance (n=763)

Human illness before bird collection (n=203, (27%))Bird collection before human illness (n=560, (73%))

West Nile VirusMosquito Surveillance

United States, 2003

U.S. Counties Reporting WNV-Positive Mosquitoes, 2003

8,385 pools41 species40 states and DC

• 2.8 million individuals tested• 8,384 WNV-positive mosquito pools

– Overall infection rate ~3 per 1,000

• 50 positive species• Earliest: 18 JAN, Cx. pipiens, Monmouth Co., NJ

– (overwintering mosquito),

– then 7 MAR, Cx. quinquefasciatus, St. Tamany Parish, LA

• Latest: 19 NOV, Cx. quinquefasciatus, Travis Co., TX

WNV Surveillance, United States, 2003*:Summary of Mosquito Data


Culex Aedes Ochlerotatus Anopheles Other cont.

erraticus aegypti atlanticus nigromaculis atropos Cs. melanura

erythrothorax albopictus atropalpus provocans barberi Cs. morsitans

nigripalpus cinereus canadensis sollicitans cruciansCq.

perturbans

pipiens vexans cantator sticticus franciscanus De.cancer

quinquefasciatu

sdorsalis stimulans punctipennis Or. signifera

restuans fitchii taeniorhynchusquadrimaculatu

sPs. ciliata

salinarius grossbecki triseriatus walkeri Ps. columbiae

tarsalis infirmatus trivittatus Other Ps. ferox

territans japonicus Cs. impatiens Ps. howardii

Cs. inornata Ur. sapphirina

“Top 10” WNV-Positive Mosquito Species Reported, By Number of WNV-Positive Pools,

United States, 2001-2003*


20012001 20022002 20032003

Cx. pipiensCx. pipiens (349) (349) Cx. species (2124)Cx. species (2124) Cx. species (1904)Cx. species (1904)

Cx. species (184)Cx. species (184) Cx. pipiensCx. pipiens (1536) (1536) Cx. tarsalisCx. tarsalis (1746) (1746)

Cx. pip/rest (119)Cx. pip/rest (119) Cx. pip/rest (1186)Cx. pip/rest (1186) Cx. pipiensCx. pipiens (1152) (1152)

Cx. restuansCx. restuans (76) (76) Cx. quinq (625)Cx. quinq (625) Cx. quinqCx. quinq (1060)(1060)

Cx. salinarius (70)Cx. salinarius (70) Cx. restuansCx. restuans (298) (298) Cx. restuansCx. restuans (850)(850)

Cs. melanura (26)Cs. melanura (26) Cx. tarsalisCx. tarsalis (249) (249) Cx. pip/rest (625)Cx. pip/rest (625)

Oc. triseriatus (13)Oc. triseriatus (13) Cx. salinarius (119)Cx. salinarius (119) Cx. pip complexCx. pip complex (272)(272)

Cx. quinq (13)Cx. quinq (13) Ae. albopictus (66)Ae. albopictus (66) Cx. salinariusCx. salinarius (247)(247)

Oc. japonicus (8)Oc. japonicus (8) Oc. triseriatus (63)Oc. triseriatus (63) Ae. vexans (126)Ae. vexans (126)

Oc. sollicitans (6)Oc. sollicitans (6) Ae. vexans (62)Ae. vexans (62) Cs. melanura (69)Cs. melanura (69)


Counties Reporting Mosquito and Human Surveillance (n=333)

Human illness before mosquito collection (n=103, (31%))

Mosquito collection before human illness (n=230, (69%))

Timing of WNV-Positive Mosquito Pool Collection and Human WNV Case Onset, By County, United States, 2003*

West Nile Virus Equine Surveillance

United States, 2003

U.S. Counties Reporting Equine WNV Disease Cases,

2003

5,251 cases1,294 counties43 states

63733

5,251

14,571

250

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

11000

12000

13000

14000

15000

1999

2000

2001

2002

2003

Year

# ca

ses

rep

ort

edEquine WNV Disease Cases Reported,

United States, 1999-2003*

Total: 20,643 cases


West Nile VirusHuman Disease Surveillance

United States, 2003

Reported WNV Disease Cases in Humans,United States, 1999-2003*


Year # Cases # States # Counties Onset Date Range

19991999 6262 11 66 2 AUG – 24 SEP2 AUG – 24 SEP

2000 21 3 10 20 JUL – 27 SEP

2001 66 10 39 13 JUL – 7 DEC

2002 4,156 39** 740 19 MAY – 19 DEC

20032003 9,8629,862 45**45** 10791079 14 APR – 5 DEC14 APR – 5 DEC

** Plus D.C.

U.S. Counties Reporting Human WNV Disease Cases, 2003

9,862 cases1,079 counties45 states and DC

WNND County Level Incidence per Million, United States, 2002*

Incidence per million

.01-9.99

10-99.99

>=100


WNND County Level Incidence per Million, United States, 2003*

*Reported as of 5/20/2004

Incidence per million

.01-9.99

10-99.99

>=100

Conclusions

• Continuing need for WNV surveillance– Detecting first activity– Secular trends– Allocation of resources

• Funding stable for forseeable future

• Continuing data challenges– Quality?– What type is appropriate?– What is available?

Questions?


2002 (All)

2002 2002 (Fatal)(Fatal)

2003 (All)*

2003 2003 (Fatal)*(Fatal)*

N

Clinical category

4,146 284284 9,737 260260

WNND 71% 97%97% 28% 88%88%

WN Fever 28% 2%2% 70% 7%7%

Other Clinical N/A N/AN/A <1% 2%2%

Unknown 1% <1%<1% 1% 3%3%

Age (yr)

median 55 7777 47 7676

range 0 – 99 19 – 9919 – 99 0 – 99 0 – 970 – 97

Males 53% 64%64% 53% 64%64%

Mortality 7%** 3%***

** 9% of WNND Cases

WNV Human Disease Cases, Demographics & Mortality, United States, 2002 vs 2003*

*** 8% of WNND Cases

Common Arboviruses in the United StatesCalifornia Serogroup

Eastern equine Western equine

St. Louis

Spring FallSummer Winter

Total females (e.g., light traps)

Infected female mosquitoes

Overwintering (diapause) females

Human cases

Infected birds

Temporal pattern of arbovirus activity: vectors, birds, and humans

Larvicide, source reduction

Adult control

Aedes aegypti, the yellow fever mosquito

A Favored Breeding Place for Aedes aegypti

ArboNET and the ArbonautsArboNET and the Arbonauts: Rapid Reporting Systems for

Vector-borne and Zoonotic Disease

Summary of West Nile Virus Activity in the United States,

2003

The Arbonet Team

Division of Vector-Borne Infectious Diseases

Fort Collins, Colorado

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