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  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

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

JRA

Reinfestation of

Aedes aegypti

1930s 1970 2002 HCP/HCT/VBD

PAHO/WHO 2002

JRA Aedes aegypti: Distribution throughout the world HCP/HCT/VBD

PAHO/WHO 2002

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

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

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)

Upcoming Study



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

Tucson, Arizona-Ambos Nogales corridor

Tucson Nogales Arizona Mexico

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

Brownsville, Texas Matamoros, Tamaulipas Matamoros

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.

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

.

Results

Matamoros Brownsville Households Serum Samples 111 132 118 141 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).

*

Selected Housing Characteristics of Matamoros and Brownsville Residents

Central air conditioning Room air conditioning Intact screens Mean no. occupants/residence

Matamoros

4% 27% 65% 5.4 Mean distance to neighbors (m) Mean lot size (m 2 ) 3.8 307 Store water for household use 30% Crossed border in previous 3 months 46%

Weighted point estimates Brownsville

46% 40% 61% 5.0 10.8

1070 2% 46%

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

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

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