What type of infections are typically associated with T cell deficiencies?

T cell deficiencies primarily impact the body's ability to mount effective responses against viral and certain types of fungal infections. This is because T cells, particularly CD4+ T helper cells, play a crucial role in coordinating the immune response against intracellular pathogens, including viruses, as well as some fungi.

When T cells are deficient, the immune system struggles to control latent viral infections or to respond appropriately to new viral challenges, leading to an increased susceptibility to low-grade viral and fungal infections. These infections may not cause severe illness in individuals with fully functioning immune systems but can become problematic in those with T cell deficiencies.

Additionally, encapsulated organisms typically represent a greater risk in individuals with B cell deficiencies as these organisms require antibody-mediated opsonization for effective clearance. Streptococcal infections are often adequately controlled by neutralizing antibodies and do not predominantly arise from T cell deficiencies. Opportunistic infections, although associated with T cell dysfunction, mainly describe infections caused by pathogens that generally do not cause disease in individuals with normal immune systems, typically associated with severe immune compromise.

Thus, the correct answer reflects the specific pattern of infection seen in the context of T cell deficiencies, emphasizing the role of T cells in defending against certain viral and fungal pathogens.