People are at increased risk of infection with tuberculosis (TB) when they:

• Have close contact (such as living in the same house) with someone who has active TB, which can be spread to others. Active TB is very contagious.
• Care for people who have untreated TB, such as health professionals.
• Live or work in crowded conditions where they can come into contact with people who may have untreated active TB. This includes people who live or work in prisons, nursing homes, military barracks, or homeless shelters.
• Have poor access to health care, such as homeless people, migrant farm workers, or people who abuse alcohol or drugs.
• Travel to or from regions where untreated TB is common, such as Latin America (countries in Central America, South America, and the Caribbean), Africa, Asia, Eastern Europe, and Russia.

People who have an infection that cannot spread to others (latent TB infection) are at risk of developing active TB if they:

• Have a condition or disease that weakens the immune system, such as human immunodeficiency virus (HIV) infection, some cancers, or poorly controlled diabetes.
• Have poor access to health care, such as homeless people, migrant farm workers, or people who abuse alcohol or drugs.
• Take medications that contain corticosteroids for a long period of time or are taking tumor necrosis factor-alpha antagonists (used to treat rheumatoid arthritis or Crohn's disease)..
• Have a condition that results in an impaired immune system, which can occur in older adults, newborns, women who have recently given birth, or people who have had an organ transplant and are taking medications to prevent organ rejection.
• Have a chronic lung disease caused by inhaling sand-like dust (silicosis).
• Have celiac disease.²
• Have had gastric bypass surgery or a gastrectomy.
• Are 10% or more under their healthy body weight.