Background: In some low prevalence settings, Trachoma may be eliminated with 1-2 rounds of community wide antibiotic coverage (MDA) while in others trachoma elimination takes 3 or more rounds of treatment for elimination. Clustering of infection may lead to persistence and reemergence of infection after MDA. Objectives: To determine if C. Trachomatis infection clusters at the household level in a low prevalence, antibiotic treated village in Kongwa District, Tanzania. Methods: A village in the Kongwa District Tanzania will be selected based on predicted infection prevalence of 5-9%. GPS mapping of all of the households in the village will be performed. Consenting children less than 10 years will be screened clinically for Trachoma and tested for C. Trachomatis infection via ocular swabbing and polymerase chain reaction. Clustering will be detected using k-function analysis in R. The presence of significant clustering of households with children infected with C. Trachomatis will be determined using the difference in kfunctions between infected and non-infected households. Institutional Support: The Kongwa district is a region with multiple trachoma studies underway. I will have support from study personnel for housing, food, transportation, clinical examination, swabbing for trachoma and GPS mapping. We will have support from the Johns Hopkins Chlamydia laboratory to run PCR samples. I will have access to our group biostatistician and faculty familiar with spatial statistics at Bloomberg for support with statistical analysis.