Why are infants, older adults, and people with weakened immune systems especially vulnerable to miliary tuberculosis?

Infants, older adults, and individuals with weakened immune systems are particularly vulnerable to miliary tuberculosis because their bodies lack the robust immune response necessary to effectively contain the primary infection.1

In healthy children and adults, the body typically responds to the tubercle bacillus by sequestering the bacteria within tubercles, effectively sealing them off and preventing further spread. However, when the immune system is underdeveloped, aging, or compromised—such as in organ transplant recipients or patients with AIDS—this defensive reaction is often insufficient.1

Without an effective immune barrier, the bacilli can enter the bloodstream and disseminate throughout the body, traveling to various tissues and organs, including the lymph nodes, bones, and brain. This widespread dissemination characterizes miliary tuberculosis, which is considered a highly fatal form of the disease if it is not treated with appropriate medical intervention.1