Texas lifestyle limits transmission of dengue virus

Emerging Infectious Diseases, Jan, 2003 by Paul Reiter, Sarah Lathrop, Michel Bunning, Brad Biggerstaff, Daniel Singer, Tejpratap Tiwari, Laura Baber, Manuel Amador, Jaime Thirion, Jack Hayes, Calixto Seca, Jorge Mendez, Bernardo Ramirez, Jerome Robinson, Julie Rawlings, Vance Vorndam, Stephen Waterman, Duane Gubler, Gary Clark, Edward Hayes

Table 1. Seroprevalence of anti-dengue immunoglobulin G (IgG) and
IgM antibodies in Nuevo Laredo, Mexico, and Laredo, Texas, United
States

                    Nuevo Laredo            Laredo

Households              313                  309
Serum samples           288                  228
IgM prevalence   16% (12 to 20) (a)   1.3% (0 to 3) (a)
IgG prevalence   48% (41 to 55) (a)   23% (17 to 28) (a)

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

Table 2. Selected housing and travel characteristics in Nuevo Laredo
and Laredo residents

Characteristic                               Nuevo Laredo   Laredo

Central air-conditioning                          2%         36%
Room air conditioner                             23%         52%
Evaporative cooler                               29%         17%
Screens on windows                               54%         78%
Intact window screens                            36%         60%
Mean no. occupants/residence                     4.5         3.8
Mean distance to neighbors (m)                   3.0         4.5
No travel outside Laredo/Nuevo Laredo area       70%         63%
Crossed border within 3 months of survey         52%         43%

Table 3. Risk factors associated with anti-dengue immunoglobulin
M (IgM) seropositivity in Nuevo Laredo/Laredo residents, by
univariate analysis

                                                 Mean value for IgM
Risk factor                 Prevalence ratio   seropositive residents

No air-conditioning               2.6                    --
Evaporative cooler                2                      --
No travel beyond Laredo/
  Nuevo Laredo area               1.9                    --
No. room air conditioners          --                   0.3
Distance to neighbor (m)           --                   2.4

                                                     (95% confidence
                              Mean value for IgM        interval)
Risk factor                 seronegative residents     or p value

No air-conditioning                   --              (1.3 to 5.2)
Evaporative cooler                    --              (1.2 to 3.3)
No travel beyond Laredo/
  Nuevo Laredo area                   --              (1.0 to 3.5)
No. room air conditioners            0.6                  0.05
Distance to neighbor (m)             3.8                  0.003

Table 4. Risk factors associated with anti-dengue IgG seropositivity
in Nuevo Laredo/Laredo residents, by univariate analysis

                                                 Mean value for IgG
Factor                      Prevalence ratio   seropositive residents

No air-conditioning               1.65                   --
No. occupants                      --                   4.7
Lot size ([m.sup.2])               --                   377
No. room air conditioners          --                   0.4
Distance to neighbor (m)           --                   3.3

                                                     (95% confidence
                              Mean value for IgG        interval)
Factor                      seronegative residents     or p value

No air-conditioning                   --             (1.27 to 2.15)
No. occupants                        4.3                  0.05
Lot size ([m.sup.2])                 395                  0.03
No. room air conditioners            0.7                  0.002
Distance to neighbor (m)             3.9                  0.03

Table 5. Estimated cost (US dollars) of air-conditioning a house in
Texas vs. Taumalipas, Mexico

                                Texas    Taumalipas

Cost per kilowatt hour (kWh)   0.06119    0.04863
Cost of 25,000 kwh              1,530      1,216
Per capita GDP (a)             34,288      5,014
% of per capita GDP              4.5        24.2

(a) GDP, gross domestic product.