Basic and Clinical Sciences (BCSE) Practice Exam

Wallgren’s timetable of childhood tuberculosis outlines the sequence of immunological and clinical responses that occur following infection with Mycobacterium tuberculosis. In this context, the development of cell-mediated immunity (CMI) and hypersensitivity is a vital stage in the immune response to tuberculosis.

Upon initial exposure to the tuberculosis bacterium, the immune system begins to respond. CMI is crucial for controlling and containing the infection, as it involves the activation of T-cells and other immune mechanisms that can recognize and attack the infected cells. Hypersensitivity, particularly in the form of delayed-type hypersensitivity, is measured through tests like the tuberculin skin test, indicating that the individual has developed an immune response to the pathogen. This response typically occurs several weeks after exposure, alongside the establishment of the infection.

In contrast, the other options reflect either incorrect timelines or mischaracterizations of tuberculosis pathophysiology. For example, meningitis or bone disease occurring very early in the infection process is not typical and suggests a more complicated and advanced progression of the disease rather than the initial response of the immune system outlined by Wallgren’s model. Additionally, extrapulmonary manifestations, while possible, do not typically present within a week of infection; such conditions usually develop after