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The number of cases of tuberculosis in children younger than five years of age in cities has increased 94.3% in the last four years. Tuberculosis infection is initiated by the inhalation of organisms into the lung. During an incubation period that lasts 2 to 10 weeks, the organisms spread to the hilar lymph nodes. The condition is now considered primary tuberculosis. During the incubation period, the purified protein derivative (PPD) test usually becomes
Primary tuberculosis is often completely asymptomatic, and the chest radiograph may be only minimally abnormal, with hilar adenopathy, and/or small parenchymal infiltrates. Healed primary tuberculosis may leave calcified deposits in the
Extrapulmonary disease is more common in children than in adults. In children, 25% of tuberculosis disease is extrapulmonary, whereas 15% isextrapulmonary in adults. Children and young adolescents are more likely than adults to have meningitis, miliary tuberculosis, adenitis, and bone and
Pulmonary disease develops in 40% of children younger than one year of age who have untreated tuberculosis. Untreated children between one and five years of age have a 24% risk of pulmonary tuberculosis, and untreated adolescents 11 to 15 years of age have a
Children who do not have clinical disease, but who harbor a reservoir of quiescent organisms may develop tuberculous disease later in life. Reactivation is most likely to occur during adolescence, during an episode of immunosuppression, in the presence of chronic disease, or in the elderly. The lifetime risk of developing active tuberculosis is 0.1% per year.
Diagnosis of Tuberculosis in Children
Children Exposed to Tuberculosis
All household contacts of adults with active disease should be tested by PPD. Thirty to 50% of all household contacts of infectious adults will have a positive PPD.
Children who are known contacts and who are PPD negative, should receive prophylactic therapy, usually isoniazid (Laniazid), 10 mg/kg/day. The PPD is repeated in 3 months to check for conversion to a positive PPD test, which would indicate infection. If the repeat PPD test remains negative, the child is assumed not to be infected, and prophylactic therapy can be discontinued. If the repeat PPD test is positive, the child should be treated for 9 months.
Any child with a positive PPD test should be evaluated for active pulmonary and extrapulmonary tuberculosis with a history and physical examination and posteroanterior and lateral chest radiographs. The source of the child's infection should be determined, and the susceptibility of the source case's M. tuberculosis strain is considered in selecting prophylactic or treatment regimen. Contact with the person with contagious tuberculosis who infected the child must be stopped until the source case is
Children at Risk for Infection
A PPD test is recommended for children in high-risk groups. A screening PPD test of 5 tuberculin units can be placed before a dose of measles-mumps-rubella (MMR) vaccine, simultaneously with the MMR vaccine dose, or 6 weeks after the MMR vaccine dose. A false-negative PPD test may occur within 6 weeks of an MMR vaccination, because of transient immunosuppression from the
The size of the PPD reaction determined to be positive varies with the risk of