Dengue Fever Seroprevalence and Risk Factors, Texas–Mexico Border, 2004

Reported autochthonous dengue fever transmission in the United States has been limited to 5 south Texas border counties since 1980. We conducted a cross-sectional serosurvey in Brownsville, Texas, and Matamoros, Tamaulipas, Mexico (n = 600), in 2004 to assess dengue seroprevalence. Recent dengue infection was detected in 2% (95% confidence interval CI 0. 5%-3. 5%) and 7. 3% (95% CI 4. 3%-10. 3%) of residents in Brownsville and Matamoros, respectively. Past infection was detected in 40% (95% CI 34%-45%) of Brownsville residents and 78% (95% CI 74%-83%) of Matamoros residents. For recent infection, only weekly family income <or=100 was a significant predictor (adjusted odds ratio 3. 2, 95% CI 1. 3-8. 0). Risk factors that predicted past dengue infection were presence of larval habitat, absence of air-conditioning and street drainage, and weekly family income <or=100. Mosquito larvae were present in 30% of households in both cities. Our results show that dengue fever is endemic in this area of the southern Texas-Mexico border.