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 ...

<0.0001 with the addition of city to the model. Several variables that predicted past dengue infection changed significantly with the addition of the city variable to the model including stored water, street drainage, air-conditioning, and income, indicating that the influence of these factors on past infection differed by city. We tested for collinearity among all independent variables and found none; variance inflation factors (VIF) for all tests were [less than or equal to]1.82, mean VIF = 1.26, far lower than the accepted VIF>

<0.001 
Mean persons/household         3.9             4.2          0.028 
Mean hours/day at home         18.3            19.4         0.022 
 
* Probability values of variables with percentages by adjusted 
Wald test; the remainder by 2-sample Wilcoxon-Mann-Whitney 
rank-sum test. 
 
Table 4. Logistic regression results for recent dengue 
infection in Brownsville, Texas, and Matamoros, Mexico, 
2004 * 
 
                       Adjusted              95% Confidence 
Variable              odds ratio   p value      interval      Deff 
 
Income [less than 
  or equal to] $100      3.22       0.012      1.31-7.95      0.95 
Missing income           1.35       0.671      0.34-5.42      1.00 
Street drainage          0.69       0.395      0.29-1.65      1.00 
Larval habitat           2.20       0.381      0.37-13.07     0.74 
Air-conditioning         0.74       0.543      0.28-1.96      0.94 
Intact screens           0.98       0.959      0.41-2.32      1.06 
Store water              1.17       0.709      0.51-2.68      0.90 
Aedes aegypti            1.05       0.912      0.47-2.31      0.92 
Cross border, 3 mo       0.95       0.900      0.40-2.24      1.05 
People/household         0.97       0.727      0.80-1.17      0.88 
 
* Missing data in independent variables (n = 22) did 
not significantly change prevalence of recent or past 
dengue infection (p>