Final answer:
A diagnosis of severe combined immunodeficiency (SCID) is likely based on the infant's symptoms, and it is a genetic condition with severely compromised immunity. The most common form is X-linked, affecting males, and treatment usually involves a bone marrow transplant, although this carries significant risks.
Step-by-step explanation:
The clinical presentation described suggests a diagnosis of severe combined immunodeficiency (SCID), a genetic condition characterized by the absence of a functional immune system due to defects in T cells and B cells. Patients with SCID often lack a thymus and present with severe lymphopenia and recurrent severe infections. These infections can be caused by opportunistic organisms such as Candida spp., Pneumocystis jirovecii, or pathogenic strains of E. coli. SCID can be inherited through various genetic patterns, with the most common form being X-linked SCID, affecting primarily males. Treatment typically involves a bone marrow transplant, which has the potential to correct the defective lymphocyte development. However, this treatment comes with significant risks, as demonstrated by the case of David Vetter, who died after a bone marrow transplant due to an Epstein-Barr virus infection transmitted through the donated bone marrow.