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ESSENTIALS OF DIAGNOSIS

ESSENTIALS OF DIAGNOSIS

  • Modes of transmission: sexual contact with an infected person, parenteral exposure to infected blood (needle sharing, very rarely with transfusion), perinatal exposure.

  • Prominent systemic complaints: sweats, diarrhea, weight loss, and wasting.

  • Opportunistic infections due to diminished cellular immunity—often life-threatening.

  • Aggressive cancers, particularly non-Hodgkin lymphoma.

  • Neurologic manifestations, including dementia, aseptic meningitis, and neuropathy.

GENERAL CONSIDERATIONS

When AIDS was first recognized in the United States in 1981, cases were identified by finding severe opportunistic infections such as Pneumocystis pneumonia that indicated profound defects in cellular immunity in the absence of other causes of immunodeficiency. When HIV was identified as the cause of the syndrome, it became obvious that severe opportunistic infections and unusual neoplasms were at one end of a spectrum of disease, while healthy seropositive individuals were at the other end.

The earliest stage of HIV infection is acute infection. Acute retroviral syndrome, while not universal, is characterized by an illness with systemic symptoms including fever, rash, pharyngitis, swollen lymph nodes, and aseptic meningitis. Diagnosis is made in a patient who was previously known to be living without HIV or of unknown HIV status in whom these characteristic symptoms develop following an exposure to HIV. Diagnosis of acute HIV is made by finding a positive HIV viral load in the setting of characteristic symptoms, with or without a positive HIV antigen/antibody test in cases which the patient is still in the window period. If acute infection is suspected but the HIV viral load test is negative, the test should be repeated in 1–2 weeks. In patients with acute infection, antibodies subsequently will develop with time, although seroconversion with pre-exposure prophylaxis can delay their development. Patients with acute or newly diagnosed infection should receive prompt antiretroviral treatment (see Treatment section, below).

Not all patients living with HIV infection have a diagnosis of acute illness. Patients may convert from being HIV antibody–negative to positive without showing symptoms or having come to medical attention. Once the acute infection stage has passed, patients generally enter an asymptomatic phase; in the years before effective antiviral therapy, it was found that this asymptomatic stage could last for years, although during this stage the immune system was being harmed and systemic inflammation occurred.

The classification "AIDS" defines the late stage of HIV infection.

The CDC AIDS case definition (Table 31–1) includes opportunistic infections and malignancies that rarely occur in the absence of severe immunodeficiency (eg, Pneumocystis pneumonia, CNS lymphoma, cytomegalovirus retinitis). It also classifies persons as having AIDS if they have a positive HIV antibody test and certain infections and malignancies that can occur in immunocompetent hosts but that are more common among persons living with HIV infection (eg, pulmonary tuberculosis, invasive cervical cancer). Several nonspecific conditions, including dementia and wasting (documented weight loss)—in the presence of a positive HIV test—are also ...

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