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Dengue along the US/Mexico Border

Dengue along the US/Mexico Border. Mary Hayden, PhD NCAR Climate and Health Colloquium July 19, 2006. Presentation Outline. Dengue Overview Dengue along the US/Mexico Border Research projects Questions?. Dengue Background. Most common viral disease transmitted by arthropod vectors

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Dengue along the US/Mexico Border

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

  5. Distribution of Aedes aegypti in the United States, 2001 Current status Positive Negative/Eradicated Intercepted Unknown

  6. 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

  7. 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)

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

  9. Tucson, Arizona-Ambos Nogales corridor Tucson Nogales Arizona Mexico

  10. 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

  11. Matamoros Brownsville, Texas Matamoros, Tamaulipas

  12. 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.

  13. 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.

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

  15. 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

  16. 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

  17. 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

  18. 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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