1750 clinically-well, adult (age 18-55 years), recent immigrants (<2 years U.S. residence), referred through cooperating public health clinics in the Santa Clara Valley area, CA will be screened for H. pylori, helminth, and latent tuberculosis infections ["Screening" population]. Of these 1750, 426 will be selected for more intensive study (Cohort population), 105 of whom will receive baseline endoscopy. Of those selected for the cohort, 300 are expected to complete a 9-month follow-up assessment, 75 of whom are expected to undergo a second follow-up endoscopy.