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Dengue along the US/Mexico Border

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Title: Dengue along the US/Mexico Border


1
Dengue along the US/Mexico Border
  • Mary Hayden, PhD
  • NCAR Climate and Health Colloquium
  • July 19, 2006

2
Presentation Outline
  • Dengue Overview
  • Dengue along the US/Mexico Border
  • Research projects
  • Questions?

3
Dengue Background
  • Most common viral disease transmitted by
    arthropod vectors
  • Endemic tropics and subtropics
  • 50-100 million annual cases worldwide
  • 250,000-500,000 annual cases dengue hemorrhagic
    fever (DHF)
  • Four serotypes (DEN-1 through DEN-4)

Aedes aegypti Aedes albopictus
4
Resurgence in Americas
  • Ae. aegypti eradication programs
  • 1946 -1970 Pan American Sanitary Board
    prevention of urban yellow fever epidemics
  • Mexico achieved eradication
  • Reinfestation since late 1970s
  • waning support for mosquito control
  • unregulated urbanization
  • plentiful larval habitats non-biodegradable
    products

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7
Distribution of Aedes aegypti in the United
States, 2001
Current status
Positive
Negative/Eradicated
Intercepted
Unknown
8
Dengue in Mexico and at the US Border
  • Mexico
  • Non-endemic (no viruses) 1970s
  • Hypoendemic (one serotype present) DEN-1 1979
  • Hyperendemic (multiple serotypes) DEN-4 1984
  • Increased epidemic activity and emergence of DHF
    as public health problem
  • South Texas
  • No dengue 1950-1980
  • 5 outbreaks since 1980

9
Current Studies
  • Tucson, AZ/Ambos Nogales since 2002 documenting
    the re-invasion of a tropical mosquito in the
    Sonoran desert after a 40 yr absence (NOAA OGP
    funded)
  • Brownsville, TX and Matamoros, Tamaulipas
    investigation of dengue outbreak in 2005 (BIDS,
    CDC, local and state health departments in TX and
    MX)

10
Upcoming Study
  • Brownsville, TX and Matamoros, Tamaulipas
    investigation of the role of waste tires as
    mosquito breeding sites (PAHO and EPA)

11
Tucson, Arizona-Ambos Nogales corridor
Tucson
Nogales Arizona
Mexico
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15
Summary
  • Pre, during, and post monsoon, vegetation is
    strongly conducive to Ae. aegypti presence
  • Controlling for different locations
  • Greater max T is detrimental pre-monsoon
  • Higher RH conducive post-monsoon
  • Greater saturation deficit conducive during the
    monsoon
  • Important human ecology differences among three
    study sites

16
Brownsville, Texas Matamoros, Tamaulipas
17
Matamoros and Brownsville, 2005
  • Tamaulipas, Mexico experienced a dengue epidemic
    in mid-late 2005 with over 4000 dengue cases
    reported by mid-October, a six-fold increase from
    2004. Dengue-2 was the predominant serotype.
  • Between Sept and Dec 2005, 6 people were
    identified from Brownsville with dengue fever and
    6 with DHF, including one case of locally
    acquired DHF.
  • In December 2005 a binational seroepidemiologic
    investigation was conducted to define the
    prevalence of anti-dengue antibodies in both
    cities.

18
Methods
  • We used a two stage cluster sampling to select a
    representative sample of households in
    Brownsville and Matamoros.
  • All individuals aged 5 years or older were
    eligible for interviews and phlebotomy. Serum
    samples were tested for anti-dengue IgM and IgG
    antibodies using enzyme-linked immunosorbent
    assay (ELISA).
  • Household questionnaires and entomological
    surveys were conducted.

19
Results
Matamoros Brownsville
Households 111 118
Serum Samples 132 141
IgM positive 22.8 (13.3 to 32.3) 2.54 (0 to 5.4)
IgG positive 82.5 (72.4-92.6) 49.7 (37.5 to 61.9)
Weighted point estimate and (95 confidence
interval).
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22
Selected Housing Characteristics of Matamoros and
Brownsville Residents
  • Matamoros
    Brownsville
  • Central air conditioning 4 46
  • Room air conditioning 27 40
  • Intact screens 65 61
  • Mean no. occupants/residence 5.4 5.0
  • Mean distance to neighbors (m) 3.8
    10.8
  • Mean lot size (m2) 307 1070
  • Store water for household use 30 2
  • Crossed border in previous 3 months
    46 46

Weighted point estimates
23
Summary
  • The first case of DHF acquired in continental US
    was reported
  • Preliminary serology data many more cases of
    dengue infection in Matamoros than in Brownsville
  • May be highest prevalence of anti-dengue
    antibodies described in continental US in last 50
    years

24
Acknowledgements Tucson/Ambos Nogales
  • Andrew Comrie, University of Arizona
  • Mercedes Gameros, Binational Office, Sonora MX
  • Duane Gubler, University of Hawaii
  • Henry Hagedorn, University of Arizona
  • Craig Janes, Simon Fraser University
  • Craig Levy, Arizona Department of Health Services
  • Linda Mearns, National Center for Atmospheric
    Research
  • Frank Ramberg, University of Arizona
  • Cecilia Rosales, University of Arizona
  • Chris Uejio, University of Arizona
  • Kathleen Walker, University of Arizona

25
Acknowledgements Brownsville/Matamoros
  • Jurisdicción Sanitaria No. III de Matamoros
  • Servicios de Salud de Tamaulipas
  • Dirección General de Epidemiología
  • Brownsville City Health Department
  • Texas Department of State Health Services
  • University of Colorado
  • CDC
  • Division of Global Migration and Quarantine
  • Division of Vector-Borne Infectious Diseases
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