Survey forms were received at the offices of the CDC-UVG Collaboration at the Universidad del Valle de Guatemala for optical scanning into a database using the Cardiff Teleform system (Vista, CA). Each Teleform entry was checked manually with the original forms to ensure accurate scanning and coding. Socioeconomic status (SES) was estimated using a wealth index generated using the factor effects derived from the first principle component of a principle component analysis of household goods, house construction material, source of water supply, source of cooking fuel and sanitation facility; the wealth index was categorized into quintiles with households weighted by number of residents and sample weights. [16, 17] To account for the complex survey design, sample weights were applied in all analyses. We used the Wald Chi-square statistic to test for differences between proportions and logistic regression to test for trends related to age and SES. Analyses were conducted with SAS version 9.1 (SAS Institute, Cary, NC) using PROC SURVEYFREQ or PROC SURVEYLOGISTIC.