According to the Public Health Agency of Canada, primary complex in children is the initial phase of tuberculosis that is commonly asymptomatic and is typically only diagnosed after a positive skin test. During primary complex, an infection develops in the lungs and typically heals, forming calcifications.
As noted by the Public Health Agency of Canada, up to 95 percent of all cases of primary complex are halted by the body's immune system response against the bacteria, which limits its growth. Once the bacteria is inhaled and primary complex develops in the lungs, the child is said to have a latent infection, which is characterized by no clinical symptoms.
Pediatric Oncall Child Health Care states that primary complex can lie dormant in children throughout childhood and lower immune function. Later in life, this bacteria can be reactivated, forming a cavity in the lungs. This is referred to as secondary or reactivation tuberculosis.
Caused by mycobacterium tuberculosis, tuberculosis infection has multiple stages. In 5 to 10 percent of cases, it progresses from the primary complex stage, the Public Health Agency of Canada says. Once the infection is progressive, symptoms include a low-grade fever, cough, weight loss, night sweats, lymphadenopathy, chest pain and pneumonia.