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Despite important advances in its treatment over the past two decades, tuberculosis remains a major infectious disease. Approximately one third of the world’s population harbors Mycobacterium tuberculosis and is at risk for developing disease in the near or distant future. The incidence and prevalence of tuberculosis increased over the past 15 years partly due to the human immunodeficiency virus (HIV) epidemic and the prevalence of drug-resistant tuberculosis. The failure to control tuberculosis in both developed and developing countries represents one of our greatest public health failures.

Epidemiology

Two elements determine a child’s risk for developing tuberculosis disease.1 The first is the likelihood of exposure to an individual with infectious tuberculosis, which is primarily determined by the individual’s environment. The second is the ability of the person’s immune system to control the initial infection and keep it clinically dormant. Without treatment, disease develops in 5% to 10% of immunologically normal adults with tuberculosis infection. In young children, the risk is greater; as many as 40% of those younger than 1 year with untreated tuberculosis infection develop radiographic or clinical evidence of tuberculosis disease. Methods of preventing disease in infected individuals benefit children and adolescents even more than adults.

About 60% of cases of childhood tuberculosis occur in infants and children younger than 5 years.2 The ages of 5 to 14 years are often called the “favored age” because children in this range may become infected, but usually have the lowest rate of tuberculosis disease. The gender ratio for tuberculosis in children is about 1:1 in contrast to adults, in whom males predominate.

Children acquire M tuberculosis from adults in their environment. Environmental risk factors include those characteristics that make it more likely that the child shares the air with an adult with infectious tuberculosis. Factors that increase the risk of a child being infected with M tuberculosis include (1) birth or travel/residence in a country in which tuberculosis is endemic; (2) early childhood environments with exposures to multiple high-risk caregivers, for example, some orphanages; or (3) contact with high-risk adults who have had previous residence in a jail, prison, or high-risk nursing home, and homelessness in some communities. Also included are use of illegal drugs, experience as a health care worker who cares for high-risk patients, or locally defined risk factors. Factors that increase the risk of developing disease once infected include age younger than 2 years, coinfection with HIV, other immunocompromising diseases or treatments (corticosteroids, tumor necrosis factor-alpha inhibitors), and malnutrition.3

Most children in the United States are infected with M tuberculosis in the home, but outbreaks of childhood tuberculosis centered in elementary and high schools, nursery schools, family daycare homes, churches, school buses, and stores have occurred.4 Childhood tuberculosis case rates in the United States and in other developed countries are strikingly higher among ethnic and racial minority groups and among the poor. In the ...

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