Dengue along the Dengue along the US/Mexico BorderUS/Mexico Border

Mary Hayden, PhDMary Hayden, PhD

NCAR Climate and Health ColloquiumNCAR Climate and Health Colloquium

July 19, 2006July 19, 2006

Presentation OutlinePresentation Outline

Dengue OverviewDengue Overview

Dengue along the US/Mexico BorderDengue along the US/Mexico Border

Research projectsResearch projects

Questions?Questions?

Dengue BackgroundDengue Background

Most common viral disease transmitted by Most common viral disease transmitted by arthropod vectorsarthropod vectors

Endemic tropics and subtropicsEndemic tropics and subtropics 50-100 million annual cases worldwide 50-100 million annual cases worldwide 250,000-500,000 annual cases dengue 250,000-500,000 annual cases dengue

hemorrhagic fever (DHF)hemorrhagic fever (DHF) Four serotypes (DEN-1 through DEN-4)Four serotypes (DEN-1 through DEN-4)

Aedes aegypti

Aedes albopictus

Resurgence in AmericasResurgence in Americas

Ae. aegyptiAe. aegypti eradication programs eradication programs 1946 -1970 – Pan American Sanitary Board –

prevention of urban yellow fever epidemics Mexico achieved eradication

Reinfestation since late 1970s Reinfestation since late 1970s waning support for mosquito control unregulated urbanization plentiful larval habitats – non-biodegradable

products

HCP/HCT/VBD

PAHO/WHO 2002

JRA

Reinfestation of Aedes aegypti1930s 1970 2002

HCP/HCT/VBD

PAHO/WHO 2002

JRA

Aedes aegypti:Distribution

throughout the world

Distribution of Aedes aegypti in the United States, 2001

Positive

Negative/Eradicated

Intercepted

Unknown

Current status

Dengue in Mexico and at the Dengue in Mexico and at the US BorderUS Border

MexicoMexico 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 TexasSouth Texas

No dengue 1950-1980 5 outbreaks since 1980

Current StudiesCurrent Studies

Tucson, AZ/Ambos Nogales since 2002 Tucson, AZ/Ambos Nogales since 2002 documenting the re-invasion of a tropical documenting the re-invasion of a tropical mosquito in the Sonoran desert after a 40 mosquito in the Sonoran desert after a 40 yr absence (NOAA OGP funded)yr absence (NOAA OGP funded)

Brownsville, TX and Matamoros, Brownsville, TX and Matamoros, Tamaulipas investigation of dengue Tamaulipas investigation of dengue outbreak in 2005 (BIDS, CDC, local and outbreak in 2005 (BIDS, CDC, local and state health departments in TX and MX)state health departments in TX and MX)

Upcoming StudyUpcoming Study

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

Tucson, Arizona-Ambos Nogales corridor

Tucson

NogalesArizona

Mexico

SummarySummary

Pre, during, and post monsoon, vegetation is Pre, during, and post monsoon, vegetation is strongly conducive to strongly conducive to Ae.Ae. aegyptiaegypti presence presence

Controlling for different locationsControlling for different locations Greater max TGreater max T°° is detrimental pre-monsoon is detrimental pre-monsoon Higher RH conducive post-monsoonHigher RH conducive post-monsoon Greater saturation deficit conducive during the Greater saturation deficit conducive during the

monsoonmonsoon

Important human ecology differences among Important human ecology differences among three study sitesthree study sites

Brownsville, TexasMatamoros, Tamaulipas

Matamoros

Matamoros and Brownsville, Matamoros and Brownsville, 20052005

Tamaulipas, Mexico experienced a dengue Tamaulipas, Mexico experienced a dengue epidemic in mid-late 2005 with over 4000 epidemic in mid-late 2005 with over 4000 dengue cases reported by mid-October, a six-dengue cases reported by mid-October, a six-fold increase from 2004. Dengue-2 was the fold increase from 2004. Dengue-2 was the predominant serotype.predominant serotype.

Between Sept and Dec 2005, 6 people were Between Sept and Dec 2005, 6 people were identified from Brownsville with dengue fever identified from Brownsville with dengue fever and 6 with DHF, including one case of locally and 6 with DHF, including one case of locally acquired DHF.acquired DHF.

In December 2005 a binational In December 2005 a binational seroepidemiologic investigation was conducted seroepidemiologic investigation was conducted to define the prevalence of anti-dengue to define the prevalence of anti-dengue antibodies in both cities.antibodies in both cities.

MethodsMethods

We used a two stage cluster sampling to select We used a two stage cluster sampling to select a representative sample of households in a representative sample of households in Brownsville and Matamoros.Brownsville and Matamoros.

All individuals aged 5 years or older were All individuals aged 5 years or older were eligible for interviews and phlebotomy. Serum eligible for interviews and phlebotomy. Serum samples were tested for anti-dengue IgM and samples were tested for anti-dengue IgM and IgG antibodies using enzyme-linked IgG antibodies using enzyme-linked immunosorbent assay (ELISA). immunosorbent assay (ELISA).

Household questionnaires and entomological Household questionnaires and entomological surveys were conductedsurveys were conducted..

ResultsResultsMatamorosMatamoros BrownsvilleBrownsville

HouseholdsHouseholds 111111 118118

Serum SamplesSerum Samples 132132 141141

IgM positiveIgM positive 22.8% 22.8%

(13.3 to 32.3)(13.3 to 32.3)**

2.54% 2.54%

(0 to 5.4)(0 to 5.4)**

IgG positiveIgG positive 82.5% 82.5%

(72.4-92.6)(72.4-92.6)**

49.7%49.7%

(37.5 to 61.9)(37.5 to 61.9)**

* Weighted point estimate and (95% confidence interval).

Selected Housing Characteristics of Selected Housing Characteristics of Matamoros and Brownsville Matamoros and Brownsville

ResidentsResidents

MatamorosMatamoros BrownsvilleBrownsville

Central air conditioningCentral air conditioning 4% 4% 46%46%

Room air conditioningRoom air conditioning 27% 27% 40%40%

Intact screensIntact screens 65% 65% 61%61%

Mean no. occupants/residenceMean no. occupants/residence 5.4 5.4 5.0 5.0

Mean distance to neighbors (m)Mean distance to neighbors (m) 3.8 3.8 10.810.8

Mean lot size (mMean lot size (m22)) 307 307 10701070

Store water for household useStore water for household use 30% 30% 2% 2%

Crossed border in previous 3 months 46%Crossed border in previous 3 months 46% 46%46%

Weighted point estimates

SummarySummary

The first case of DHF acquired in continental US The first case of DHF acquired in continental US was reportedwas reported

Preliminary serology data: many more cases of Preliminary serology data: many more cases of dengue infection in Matamoros than in dengue infection in Matamoros than in BrownsvilleBrownsville

May be highest prevalence of anti-dengue May be highest prevalence of anti-dengue antibodies described in continental US in last 50 antibodies described in continental US in last 50 yearsyears

Acknowledgements – Acknowledgements – Tucson/Ambos NogalesTucson/Ambos Nogales

Andrew Comrie, University of ArizonaAndrew Comrie, University of Arizona Mercedes Gameros, Binational Office, Sonora MXMercedes Gameros, Binational Office, Sonora MX Duane Gubler, University of HawaiiDuane Gubler, University of Hawaii Henry Hagedorn, University of ArizonaHenry Hagedorn, University of Arizona Craig Janes, Simon Fraser University Craig Janes, Simon Fraser University Craig Levy, Arizona Department of Health ServicesCraig Levy, Arizona Department of Health Services Linda Mearns, National Center for Atmospheric ResearchLinda Mearns, National Center for Atmospheric Research Frank Ramberg, University of ArizonaFrank Ramberg, University of Arizona Cecilia Rosales, University of Arizona Cecilia Rosales, University of Arizona Chris Uejio, University of ArizonaChris Uejio, University of Arizona Kathleen Walker, University of ArizonaKathleen Walker, University of Arizona

Acknowledgements – Acknowledgements – Brownsville/MatamorosBrownsville/Matamoros

Jurisdicción Sanitaria No. III de MatamorosJurisdicción Sanitaria No. III de Matamoros Servicios de Salud de TamaulipasServicios de Salud de Tamaulipas Dirección General de Dirección General de EpidemiologíaEpidemiología Brownsville City Health DepartmentBrownsville City Health Department Texas Department of State Health ServicesTexas Department of State Health Services University of ColoradoUniversity of Colorado CDCCDC

Division of Global Migration and QuarantineDivision of Global Migration and Quarantine Division of Vector-Borne Infectious DiseasesDivision of Vector-Borne Infectious Diseases