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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. The Balkanization of Science. Epidemiology. - PowerPoint PPT Presentation

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  • Introduction to vector-borne disease ecology; West Nile virus update; ArboNET structure and functionChet MooreEnvironmental Health Advanced Systems Laboratory Dept. of Environmental & radiological Health Sciences Colorado State University

  • Introduction to vector-borne disease ecology; ArboNET structure and function; West Nile virus update, 2003Chet MooreEnvironmental Health Advanced Systems Laboratory Dept. of Environmental & radiological Health Sciences Colorado State University

  • HVEBPThe Vector-borne Disease SystemUnsuitable environment (matrix)

  • Arbovirus Transmission CycleVertebrate HostVectorAdultsLarvaeEggsPupaeAquaticTerrestrialVirusVirusDead-end hosts

  • Arbovirus Transmission CycleVertebrate HostVectorAdultsLarvaeEggsPupaeAquaticTerrestrialVirusVirusDead-end hostsWeather and ClimateFood, Space, Breeding sites

    Weather and ClimateFood, Space, Breeding sites

    Predators and Pathogens

  • Impact of rain on larval habitatsImpact of rain on food supply of vertebratehost Impact of temperature on larval growthand developmentTIMEImpact of R.H. and temperature on adult survivalImpact of temperature on host and vectorwinter survivalWeather and Climate Affect the System in a Complex FashionToday

  • ArboNET Structure and FunctionThe Arbonet TeamDivision of Vector-Borne Infectious DiseasesCenters for Disease Control and PreventionFort Collins, Colorado

  • ArboNET DescriptionCDCs system for national arboviral (WNV) surveillance 57 state / metropolitan health depts.50 states and PRNYC, DC, Philadelphia, Chicago, Houston, Los AngelesPublished guidelinesCase definitions / diagnostic methods

  • ArboNET Description: National surveillance guidelines

  • Funding for SurveillanceEmerging Infections Program - CDC

    Enhanced Laboratory Capacity (ELC) programFive year cycleCooperative Agreements (renewed yearly)

    ELC and WNV funding expected to continue

  • Enhanced Laboratory Capacity (ELC) Funding, 1999-2004Awards (millions)YearMean: $2,250,792Range: $144, 311 $11,201, 533

  • Goals of national West Nile virus surveillanceTrack geographic spread in the United States

    Detect increasing virus activity before humans are at significant riskEnable interventions and educational messages

    Characterize secular trends

    Provide basis for policy / resource allocation

  • ArboNET Cast of playersState and local health departmentsCollect field and clinical specimens Conduct human epidemiologic investigations Laboratory testingData entry and reporting

    Commercial laboratorieshuman (equine) diagnostic testing

  • ArboNET Cast of PlayersCDC ArboNET staffAtlanta (server support) to Ft. Collins, 2004Fort CollinsProgrammers (2 Access, 1 Java, 1 XML)ArboNET technicians (3+)Medical epidemiologists (7)Laboratory diagnostic reference section (approx. 10)

  • 2003Peggy CollinsArbonauts: The ArboNET TeamPage 1Roy CampbellNick CrallJen BrownJohn Jones

  • Krista KnissStephanie KuhnJen LehmanTony MarfinSue MontgomeryDan OLearyPage 2!

  • ArboNET Cast of PlayersOther U.S. agenciesDepartment of DefenseMosquito collection and testing Department of AgricultureEquine diagnostic testingGeological SurveyDead bird diagnostic testingGeospatial mapping

  • ArboNET Surveillance CategoriesHumanMeningitis, encephalitis, AFP (neuroinvasive)Uncomplicated fever (non-neuroinvasive)BirdsDead (wild)Caged sentinel (chickens, pigeons)Live-caught wildNon-human mammals (horses)Mosquitoes

  • ArboNet Data Flow : State Health Department to CDCHuman, mosquito, bird, horse specimensState, Commercial, Reference LabsDOH WNV CoordinatorSuspect Human Case InvestigationsCDCPublic domain

  • Data flow through ArboNETReporting pathways (4)ArboNET stand-alone software CDC-developedMS Access-basedXML data transfer formatProprietary software Commercial or locally-producedXML data transfer formatSecure websiteCombinations

  • Data flow through ArboNET, 2002Use of reporting pathwaysArboNET (38%) Proprietary software (16%) Secure website (42%) Combinations (4%)

  • ArboNET dataNumerator (individual)Human disease casesEquine disease cases / other infected mammalsInfected birds (dead, sentinel, live-caught wild)Infected mosquito pools

    Denominator (aggregated)Total individuals tested per week and county (avian and mosquito only)

  • ArboNET dataNumerator 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 dataParticipating health departmentsWeekly conference call and secure internetUSGSWeekly data snapshot---surveillance mapsPublicPeer reviewed publicationsCDC publications (MMWR weekly updates)Maps (via CDC and USGS websites)Media interviews Senior public health officials

  • ArboNET data limitationsLag time Delays in testing and reportingData qualityAdherence to national surveillance guidelines currently unknownCase definitions (case misclassification)Testing procedures (false positives & negatives)Variabile emphasis on respective surveillance categoriesIncomplete reporting & aggregation of denominator data

  • Limitations: first activity dataDo reporting delays permit timely interventions?

    Low specificity of animal data, 20022,531 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

  • Historical PerspectiveProgression of West Nile Virus Activity in the United States, 1999-2003

  • 1999

  • 2000

  • 2001

  • 2002

  • 2003

  • States and Counties Reporting WNV Activity, United States, 1999-2003*Reported to ArboNET as of 5/20/2004

    ** Plus D.C.

    Year# States# CountiesDate Range19994289 AUG 15 NOV200012**1456 FEB 17 NOV200127**3598 APR 26 DEC200244**2,5313 JAN 19 DEC200346**2,3581 JAN 31 DEC

  • West Nile VirusBird SurveillanceUnited States, 2003

  • WNV Surveillance, United States, 2003*:Summary of Dead Bird Data97,905 dead birds reported

    25,339 tested (26%)

    12,066 WNV-positive birds reported10,200 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** 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

  • West Nile VirusMosquito SurveillanceUnited States, 2003

  • U.S. Counties Reporting WNV-Positive Mosquitoes, 20038,385 pools41 species40 states and DC

  • WNV Surveillance, United States, 2003*:Summary of Mosquito Data2.8 million individuals tested8,384 WNV-positive mosquito poolsOverall infection rate ~3 per 1,00050 positive speciesEarliest: 18 JAN, Cx. pipiens, Monmouth Co., NJ(overwintering mosquito), then 7 MAR, Cx. quinquefasciatus, St. Tamany Parish, LALatest: 19 NOV, Cx. quinquefasciatus, Travis Co., TX* Reported as of 5/20/2004

  • Top 10 WNV-Positive Mosquito Species Reported, By Number of WNV-Positive Pools,United States, 2001-2003** Reported as of 5/20/2004

  • Timing of WNV-Positive Mosquito Pool Collection and Human WNV Case Onset, By County, United States, 2003** Reported as of 5/20/2004

  • West Nile Virus Equine SurveillanceUnited States, 2003

  • U.S. Counties Reporting Equine WNV Disease Cases, 20035,251 cases1,294 counties43 states

  • Equine WNV Disease Cases Reported,United States, 1999-2003*Total: 20,643 cases* Reported as of 5/20/2004

  • West Nile VirusHuman Disease SurveillanceUnited States, 2003

  • Reported WNV Disease Cases in Humans,United States, 1999-2003** Reported as of 5/20/2004** Plus D.C.

    Year# Cases# States# CountiesOnset Date Range199962162 AUG 24 SEP20002131020 JUL 27 SEP200166103913 JUL 7 DEC20024,15639**74019 MAY 19 DEC20039,86245**107914 APR 5 DEC

  • U.S. Counties Reporting Human WNV Disease Cases, 20039,862 cases1,079 counties45 states and DC

  • WNND County Level Incidence per Million, United States, 2002** Reported as of 4/15/2003

  • WNND County Level Incidence per Million, United States, 2003**Reported as of 5/20/2004

  • ConclusionsContinuing need for WNV surveillanceDetecting first activitySecular trendsAllocation of resources

    Funding stable for forseeable future

    Continuing data challengesQuality?What type is appropriate?What is available?

  • Questions?

  • * Reported as of 5/20/2004 ** 9% of WNND CasesWNV Human Disease Cases, Demographics & Mortality, United States, 2002 vs 2003**** 8% of WNND Cases

    2002 (All)2002 (Fatal)2003 (All)*2003 (Fatal)*NClinical category4,1462849,737260 WNND71%97%28%88% WN Fever28%2%70%7%Other ClinicalN/AN/A

  • Aedes aegypti, the yellow fever mosquito

  • A Favored Breeding Place for Aedes aegypti

  • ArboNET and the Arbonauts: Rapid Reporting Systems for Vector-borne and Zoonotic Disease

  • Summary of West Nile Virus Activity in the United States, 2003The Arbonet TeamDivision of Vector-Borne Infectious DiseasesFort Collins, Colorado

    The term vector has several definitions in different branches of science (e.g., mathematics, climatology, biology). Mosquitoes are vectors of a wide variety of pathogens of human and veterinary importance (e.g., malaria, yellow fever, dengue, filariasis, and arboviral encephalitis).Many mosquito-transmitted pathogens are zoonoses; that is, they have a natural cycle that involves vertebrate hosts other than humans. Many zoonotic agents are transmissible to humans (e.g., plague, rabies, Rocky Mountain spotted fever, West Nile encephalitis, Lyme disease).

    All components of the system, pathogen, vector, and host, must occur together in time and space for epizootics or epidemics to occur. Variations in landscape structure create a patchwork of suitable and unsuitable habitats, leading to focal disease activity. Barriers, such as water bodies, deserts, or mountain ranges, may prevent the occurrence of a pathogen in an otherwise suitable location.

    The arbovirus transmission cycle involves the virus, a vertebrate host (many species of birds), and a vector (a mosquito).There are different vectors in different regions of the U.S., each with their own particular biology.Humans become involved in this cycle by accident. They are dead end hosts.Many environmental factors drive or constrain the system:Weather and climateFood and space resourcesPredators and parasitesThis creates a very complex systemIt is crucial to understand that this complexity makes it difficult to predict the occurrence of disease epidemics, both in time and in space.Appropriately collected data can aid greatly in understanding the dynamics of these diseases and can, at least in some cases, allow us to predict epidemics.

    References:

    The arbovirus transmission cycle involves the virus, a vertebrate host (many species of birds), and a vector (a mosquito).There are different vectors in different regions of the U.S., each with their own particular biology.Humans become involved in this cycle by accident. They are dead end hosts.Many environmental factors drive or constrain the system:Weather and climateFood and space resourcesPredators and parasitesThis creates a very complex systemIt is crucial to understand that this complexity makes it difficult to predict the occurrence of disease epidemics, both in time and in space.Appropriately collected data can aid greatly in understanding the dynamics of these diseases and can, at least in some cases, allow us to predict epidemics.

    References:

    We cannot simply rely on the current weeks temperature and rainfall to predict the dynamics of vector-borne diseases. Each weather variable will have multiple impacts at different points in time. The current situation can best be thought of as the integral of the action of daily weather over the past one to two years.

    As an example, here are some of the points at which weather is likely to impact on the arbovirus transmission cyclethe arrow represents an indefinite period, but covers at least 2 years.Rainfall a year or more ago is a long time from WN cases in NY City in 3 weeks ago, but it may have determined the number of juvenile crows that are available for infection.Even the high temperatures and lack of rain in June and July seem distant in time from the current epidemic in, say, August or September.Its not just temperature and rainfall--its the pattern of temperatures and when the rain falls--or doesnt fall.

    Space and time are important!

    References:

    Graphic to display the temporal sequence of mosquito, bird, and human infections with WNV (hypothetical). Can we get actual data to show this? What are the most realistic lage/offsets???

    Report feature?Historically, there have been four major arboviruses of public health importance in the U.S.: eastern and western encephalomyelitis, St. Louis encephalitis, and the California serogroup viruses (LaCrosse, Jamestown Canyon, and California). Occasionally, Venezuelan equine encephalomyelitis has invaded the Southwestern U.S. In 1999, a new virus, West Nile virus, was introduced into New York, with subsequent outbreaks in the Northeastern U.S. in 1999 and 2000.

    References:

    Graphic to display the temporal sequence of mosquito, bird, and human infections with WNV (hypothetical). Can we get actual data to show this? What are the most realistic lage/offsets???