Pediatric tuberculosis: all in the family?

Abstract

In the United States, the remarkable increase in tuberculosis (TB) (54.5%) among young adults 25 to 44 years of age (the prime childbearing and child rearing years) from 1985 to 1992 was paralleled by marked increases in TB among children.1 During the same period, cases of TB among individuals 14 years of age and younger increased 34.1%.2 Increased rates of TB among adults may be from primary infection or disease progression from remote, latent TB infection, but increased rates among children are generally caused by recent transmission of TB, thus representing a primary infection in the child. The occurrence of a recent TB infection in a child should be considered a sentinel event indicating transmission of Mycobacterium tuberculosis from an infectious adult or adolescent to that child and should routinely lead to the investigation of contacts to identify the potential source case or cases as well as other recently infected individuals. Transmission of M. tuberculosis in healthcare facilities has been documented.3-11 The magnitude of such institutional transmission varies considerably by the type of healthcare facility, the prevalence of TB in the community, the patient population served, the healthcare workers’ occupational group, the area of the healthcare facility in which the healthcare worker works, and the effectiveness of TB infection control measures.12 The risk of transmission may be higher in areas where patients with TB are provided care before diagnosis and initiation of TB treatment and isolation precautions or where diagnostic or treatment procedures that stimulate cough are performed. Children usually acquire TB from adults or adolescents. Children younger than 10 years are usually not contagious.13,14 TB in young children is rarely infectious, because young children are less likely than adults to have a productive cough, to generate the force needed to aerosolize organisms into droplet nuclei, or to have large numbers of infectious organisms in their sputum. There are case reports of children being implicated as the source of TB transmission to their contacts, however, some of whom developed active TB.15 Therefore, children with evidence of clinical TB, either signs or symptoms or abnormal results on chest radiographs, should be appropriately isolated until they have three serial acid-fast bacillus smears that are negative, receive appropriate treatment, and have decreased cough.12,14 Nosocomial TB infections in children’s wards or children’s hospitals have frequently originated from a healthcare worker or an adult visitor with unrecognized TB.16 Recommendations for healthcare facilities issued by the Centers for Disease Control and Prevention in 1994 highlight the need for instituting a hierarchy of control measures consisting of administrative, engineering, and personal protection procedures to decrease the risk of nosocomial transmission of TB.12 In this issue, Munoz et al.17 describe the importance of targeted TB screening of accompanying adults and adult visitors of children hospitalized for suspected TB at a children’s hospital in detecting unrecognized pulmonary TB, which may constitute a threat of infection to hospital staff and other patients. They emphasize that infection control procedures in pediatric facilities should take into consideration that TB in a child is a marker of recent transmission of M. tuberculosis from a close contact. Children, particularly during the first 5 years of life, may develop TB after a relatively short incubation period following infection with M. tuberculosis from a source that might not be apparent or previously identified.18,19 As suggested by Munoz et al., this source is often in the child’s household. The emphasis of screening procedures should therefore be on the adults accompanying children hospitalized with suspected TB.