This observational epidemiologic study with nested cross-sectional and longitudinal aims will evaluate host immune response to mixed chronic infections (Helicobacter pylori, latent tuberculosis, intestinal helminthiasis) in recent US immigrants.

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.

Inclusion Criteria:

• Between 18-55 years of age
• Either sex
• If female not pregnant or breastfeeding
• Lived in the United States less than 2 years
• Healthy
• Scheduled for Tuberculosis Skin Test (TST)

Exclusion Criteria:

• Under 18 and older than 55 years of age,
• Pregnant or breastfeeding
• Have lived in Unites States more that 2 years
• Chronic illness
• Not planning to get a TST

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.