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Human Immunodeficiency Virus (HIV) Infection

by J. Allen McCutchan, MD, MSc

Human immunodeficiency virus (HIV) infection results from 1 of 2 similar retroviruses (HIV-1 and HIV-2) that destroy CD4+ lymphocytes and impair cell-mediated immunity, increasing risk of certain infections and cancers. Initial infection may cause nonspecific febrile illness. Risk of subsequent manifestations—related to immunodeficiency—is proportional to the level of CD4+ lymphocytes. HIV can directly damage the brain, gonads, kidneys, and heart, causing cognitive impairment , hypogonadism, renal insufficiency, and cardiomyopathy. Manifestations range from asymptomatic carriage to AIDS, which is defined by serious opportunistic infections or cancers or a CD4 count of < 200/μL. HIV infection can be diagnosed by antibody, nucleic acid (HIV RNA), or antigen (p24) testing. Screening should be routinely offered to all adults and adolescents. Treatment aims to suppress HIV replication by using combinations of 3 or more drugs that inhibit HIV enzymes; treatment can restore immune function in most patients if suppression of replication is sustained.

(See also Human Immunodeficiency Virus (HIV) Infection in Infants and Children, the National Institute's of Health AIDSInfo web site , and the recommendations of the HIV Medicine Association of the Infectious Diseases Society of America: Primary Care Guidelines for the Management of Persons Infected with HIV .)

Retroviruses are enveloped RNA viruses defined by their mechanism of replication via reverse transcription to produce DNA copies that integrate in the host cell genome. Several retroviruses, including human T-lymphotropic virus (see HTLV Infections), cause serious disorders in people.

AIDS is defined as HIV infection that leads to any of the disorders in clinical category B or C of HIV infection (see Clinical Categories of HIV Infection*) or a CD4+ T lymphocyte (helper cell—see T cells) count of < 200/μL. The disorders in categories B and C are

  • Serious opportunistic infections

  • Certain cancers, such as Kaposi sarcoma and non-Hodgkin lymphoma, to which defective cell-mediated immunity predisposes

  • Neurologic dysfunction

Clinical Categories of HIV Infection*

Category

Disorder or Symptoms

A

Asymptomatic

Persistent generalized adenopathy

Symptoms of acute primary HIV infection

B

Bacillary angiomatosis

Candidiasis, oropharyngeal (thrush)

Candidiasis, vulvovaginal that is persistent, frequent, or poorly responsive to therapy

Cervical dysplasia (moderate or severe) or cervical carcinoma in situ

Constitutional symptoms, such as fever ( 38.5° C) or diarrhea lasting > 1 mo

Hairy leukoplakia, oral

Herpes zoster (shingles), involving at least 2 distinct episodes or > 1 dermatome

Immune thrombocytopenic purpura

Listeriosis

Pelvic inflammatory disease, particularly if complicated by tubo-ovarian abscess

Peripheral neuropathy

C

Candidiasis of bronchi, trachea, lungs, or esophagus

Cervical cancer, invasive

Coccidioidomycosis, disseminated or extrapulmonary

Cryptococcosis, extrapulmonary

Cryptosporidiosis, chronic intestinal (> 1 mo duration)

Cytomegalovirus infection (other than that of the liver, spleen, or lymph nodes)

Cytomegalovirus retinitis (with loss of vision)

Encephalopathy, HIV-related

Herpes simplex with chronic ulcers (> 1 mo duration) or bronchitis, pneumonitis, or esophagitis

Histoplasmosis, disseminated or extrapulmonary

Isosporiasis, chronic intestinal (> 1 mo duration)

Kaposi sarcoma

Lymphoma, Burkitt

Lymphoma, immunoblastic

Lymphoma of the brain, primary

Mycobacterium avium complex or M. kansasii infection, disseminated or extrapulmonary

M. tuberculosis infection, any site (pulmonary or extrapulmonary)

Mycobacterium infection by other species or unidentified species, disseminated or extrapulmonary

Pneumocystis jirovecii pneumonia

Pneumonia, recurrent

Progressive multifocal leukoencephalopathy

Salmonella septicemia, recurrent

Toxoplasmosis of the brain

Wasting syndrome due to HIV

*The CDC (1993) provided clinical categories of increasing severity based on opportunistic infections and tumors. Categories B and C represent AIDS-defining illnesses. Although categories correspond roughly with levels of immune dysfunction as measured by CD4 counts, they predict prognosis less well in patients receiving current treatments.

Added in the 1993 expansion of the AIDS surveillance case definition.

CDC = Centers for Disease Control and Prevention.

HIV-1 causes most HIV infections worldwide, but HIV-2 causes a substantial proportion of infections in parts of West Africa. In some areas of West Africa, both viruses are prevalent and may coinfect patients. HIV-2 appears to be less virulent than HIV-1.

HIV-1 originated in Central Africa in the first half of the 20th century, when a closely related chimpanzee virus first infected humans. Epidemic global spread began in the late 1970s, and AIDS was recognized in 1981. In 2011, > 34 million people were living with HIV worldwide, 1.7 million died, and 2.5 million were newly infected. Most new infections (95%) occur in the developing world, > 1/2 are in women, and 1/7 are in children < 15 yr. In many sub-Saharan African countries, incidence is declining markedly from the very high rates of a decade before.

Resources In This Article

Drugs Mentioned In This Article

  • Drug Name
    Select Trade
  • RETROVIR
  • ZOVIRAX
  • THALOMID
  • MARQIBO KIT
  • SINGULAIR
  • DARAPRIM
  • No US brand name
  • CLEOCIN
  • DOLOPHINE
  • APTIVUS
  • CYTOXAN (LYOPHILIZED)
  • NIZORAL
  • ISENTRESS
  • INVIRASE
  • PROPULSID
  • FUZEON
  • VIREAD
  • EMTRIVA
  • EPIVIR
  • LEXIVA
  • VIRAMUNE
  • CRIXIVAN
  • SPORANOX
  • ZIAGEN
  • VIDEX
  • ZERIT
  • EDURANT
  • PREZISTA
  • COUMADIN
  • NORVIR
  • ACTIQ, DURAGESIC, SUBLIMAZE
  • ESTRADERM, ESTROGEL, VIVELLE
  • INTELENCE
  • BIAXIN
  • SELZENTRY
  • SUSTIVA
  • VIRACEPT
  • REYATAZ
  • ACZONE
  • ZITHROMAX
  • DIFLUCAN
  • NEBUPENT
  • LANIAZID
  • MYCOBUTIN
  • MEPRON

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