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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
1999
2000
2001
2002
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)
* Reported as of 5/20/2004
“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
* Reported as of 5/20/2004
Timing of WNV-Positive Dead Bird Collection and Human WNV Case Onset, By County, United States, 2003*
* Reported as of 5/20/2004
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
* Reported as of 5/20/2004
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*
* Reported as of 5/20/2004
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)
* Reported as of 5/20/2004
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
* Reported as of 5/20/2004
West Nile VirusHuman Disease Surveillance
United States, 2003
Reported WNV Disease Cases in Humans,United States, 1999-2003*
* Reported as of 5/20/2004
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
* Reported as of 4/15/2003
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?
* Reported as of 5/20/2004
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