Final answer:
Memory T cells are responsible for preventing a person from getting the same disease twice by recalling the pathogen upon a second exposure and initiating a rapid, robust immune response.
Step-by-step explanation:
The type of T cells that prevents a person from having the same disease twice are known as memory T cells. Most B and T cells die after an infection has been brought under control, but memory cells persist for years, and possibly for a lifetime. These memory B and T cells allow the immune system to "remember" the pathogen after the initial infection has ended. Upon re-exposure to the same pathogen, these circulating memory cells immediately differentiate into plasma cells and Cytotoxic T Lymphocytes (CTLs) without needing input from Antigen Presenting Cells (APCs) or Helper T (TH) cells, leading to a rapid and more effective secondary immune response.
Memory B cells evolve into plasma cells that produce a markedly larger amount of antibodies than during the first encounter with the pathogen. This potent adaptive immune response can eliminate the pathogen before it establishes an infection, often without the individual even noticing the exposure. The capacity for rapid and heightened response upon subsequent exposures to the same pathogen is the foundation of immunological memory, which is crucial for long-lasting immunity against many infectious diseases.