This patient has immune reconstitution inflammatory syndrome (IRIS) caused by disseminated Mycobacterium avium complex (DMAC) infection. She developed symptoms typical for DMAC (fever, chills, sweats, fatigue, weight loss) approximately 1 month after starting antiretroviral therapy (ART). The infection was likely present before therapy initiation, but her improved immune response, made possible by treating her HIV infection, resulted in development of symptoms (the so-called “unmasking” of a preexisting infection). Her lymphadenopathy, hepatosplenomegaly, anemia, leukopenia, and elevated alkaline phosphatase level are typical signs. DMAC is usually seen in patients whose CD4 cell count is, or recently was, less than 50/µL. The diagnosis can be confirmed by culture of the blood or other normally sterile site, such as bone marrow, lymph node, or liver. A macrolide-based multidrug regimen, usually clarithromycin and ethambutol, and continued ART are the recommended treatment. IRIS is most common with mycobacterial or fungal infections but also has been reported with various opportunistic infections and with non-Hodgkin lymphoma.

Cytomegalovirus occurs in patients with AIDS with low CD4 cell counts and can present with nonspecific systemic symptoms, cytopenias, and hepatitis. However, it usually presents with focal organ involvement, most often in the gastrointestinal tract as esophagitis or colitis or in the eye as retinitis.

Candidal infection usually does not disseminate in HIV infection (compared with the risk in neutropenia) but rather causes mucocutaneous disease (such as esophagitis), which is not clinically present in this patient. Candidal infection also should not cause systemic symptoms or this patient's CT findings.

Gastrointestinal adverse effects are common with ART and often improve with time. Elevated liver enzymes may occur but often involve aminotransferases, not only alkaline phosphatase. Abacavir is associated with an uncommon hypersensitivity reaction consisting of fever, rash, gastrointestinal symptoms, hepatitis, and malaise, although abacavir toxicity would not explain this patient's lymphadenopathy or cytopenias and usually occurs shortly after therapy initiation.