Key Clinical Questions
What conditions cause symptoms in human immunodeficiency virus (HIV) patients?
How are opportunistic infections diagnosed and treated?
What noninfectious problems are common in HIV patients?
When should antiretroviral therapy be started?
More than 1.2 million people are human immunodeficiency virus (HIV) seropositive in the United States. As survival with HIV has increased because of antiretroviral therapy (ART), the spectrum of illness affecting this population has expanded. Opportunistic infections (OIs) still occur in untreated patients and patients who do not adhere to therapy. However, in patients whose HIV infection is controlled by ART, noninfectious problems such as metabolic syndrome, coronary artery disease, pulmonary hypertension, and malignancy are increasing in prevalence. This chapter uses a symptom-based approach to guide differential diagnosis in HIV, and outlines the presentation, diagnosis, and treatment of common opportunistic infections. Other aspects of HIV therapy important to the hospitalist are discussed, including medication interactions and side effects.
PATHOPHYSIOLOGY AND NATURAL HISTORY
Most patients with acute HIV infection develop symptoms between 2 and 4 weeks after exposure. Some patients are asymptomatic, but many report an acute febrile illness resembling mononucleosis. Features may include rash, anorexia, mucocutaneous ulcerations, pharyngitis, lymphadenopathy, diarrhea, myalgias, and rarely meningoencephalitis. HIV antibody does not appear until 3 to 4 weeks after the symptoms of acute HIV syndrome develop. However, fourth-generation HIV immunoassays that detect both HIV antibody and p24 antigen can detect acute HIV as early as 2 weeks after infection. Current guidelines recommend routine initial testing with a fourth-generation HIV immunoassay followed by confirmatory testing. HIV RNA (viral load) testing can detect acute infection at as early as 5 days and should be obtained if there is concern for recent infection, fourth-generation immunoassay testing is unavailable, or initial results are indeterminate. Clinicians should bear in mind that patients with acute HIV infection may also have acquired other infections, such as viral hepatitis, syphilis, or cytomegalovirus (CMV), at the time of their HIV exposure.
Human immunodeficiency virus depletes CD4+ lymphocytes, also known as T-helper cells, leading to OIs. In acute HIV infection, CD4+ cells decline sharply, generally followed by a modest rebound, as HIV replication is brought under partial control. Over time, viremia rises, CD4+ cells are gradually depleted, and acquired immunodeficiency syndrome (AIDS) develops.
The tempo for progression to AIDS has great individual variability. Illnesses such as seborrheic dermatitis, cutaneous zoster, bacterial pneumonia, and cytopenias, while not specific to HIV, occur with increased frequency in patients with waning CD4+ cells and may be a clue to undiagnosed HIV.
Admission of the patient with CD4+ count >500 cells/mm3, suppressed viral load, and admission for a non–HIV-related reason does not necessarily require infectious diseases consultation. By contrast, newly diagnosed HIV, acute opportunistic infections, undifferentiated illness in patients with more advanced HIV, or possible modification of ART warrant review by a ...