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Human immunodeficiency virus infection

Definition
HIV infection is a chronic viral disease that, if untreated, leads to progressive T cell depletion with resultant infectious and oncological complications.
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Pathophysiology
HIV-1 is responsible for the vast majority of infections, while human immunodeficiency type 2 is relatively uncommon and follows a more indolent course.
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Epidemiology
In the US, the incidence and prevalence of HIV are estimated at 18 cases per 100,000 person-years and 380.9 persons per 100,000 population, respectively.
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Disease course
Infection begins by invasion of the target cells in a mucosa, following which the infection spreads to the lymphoid system. In untreated patients, the destruction of HIV-infected CD4 T cells results in immunodeficiency and chronic inflammation. CD4 T cell counts of < 350 cells/µL are associated with an increased risk of complications such as varicella-zoster, tuberculosis, and other severe bacterial infections. The risk of opportunistic infections, such as pneumocystis pneumonia and esophageal candidiasis, increases with CD4 T cell counts of < 250 cells/µL. CD4 T cells count < 100 cells/µL result in an increased risk of coccidioidomycosis, cryptococcosis, CMV infection, histoplasmosis, progressive multifocal leukoencephalopathy, disseminated M. avium complex, brain toxoplasmosis, HIV-associated wasting syndrome, and finally death.
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Prognosis and risk of recurrence
The standardized mortality rate ratio of patients with HIV is estimated at 3.97 (95% CI 3.01-5.24) in patients who have never received ART, and 2.76 (95% CI 2.25-3.39) in patients who have been treated with ART. The 2-year and 10-year survival rates of patients diagnosed with AIDS are 82% and 26%, respectively.
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Key sources
The following summarized guidelines for the evaluation and management of human immunodeficiency virus infection are prepared by our editorial team based on guidelines from the Center for Disease Control (CDC 2021), the International AIDS Society (IAS 2018), the Clinical Pharmacogenetics Implementation Consortium (CPIC 2014), and the U.S. Preventive Services Task Force (USPSTF 2013).
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Guidelines

1.Screening and diagnosis

Indications for screening: as per IAS 2018 guidelines, screen for HIV infection at least once in all individuals who have ever been sexually active.
B
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2.Diagnostic investigations

Initial and confirmatory testing
Use assays that can detect recent HIV infection (either an instrument-based combination antigen/antibody assay or a combination of a stand-alone antibody assay and nucleic acid testing) to screen for HIV infection.
B
Obtain confirmatory measurement of HIV RNA levels in patients with positive screening results.
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  • Baseline laboratory investigations

  • Testing for HLA-B5701

  • Bone mineral density testing

  • Evaluation for comorbidities

3.Medical management

General principles: initiate ART as soon as possible after diagnosis, including immediately after diagnosis, unless the patient is not ready to commit to starting therapy.
A

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  • Initial ART

  • ART initiation (rapid start)

  • ART initiation (opportunistic infections)

  • ART switching (virologic failure)

  • Prophylaxis for opportunistic infections

4.Specific circumstances

Pregnant patients: advise individuals with HIV infection who are pregnant to initiate ART as soon as possible, for their own health and to reduce transmission to the infant.
A
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  • Patients with HBV co-infection

  • Patients with HCV co-infection

  • Patients with osteoporosis

  • Patients with kidney disease

  • Patients with tuberculosis

  • Patients with substance use disorders

  • Patients who are carriers of HLA-B57:01

5.Patient education

Sexual behavior counseling: remind HIV-seropositive and HIV-negative individuals that condoms are required to prevent acquisition of non-HIV STIs.
B

6.Preventative measures

Pre-exposure prophylaxis: as per CDC 2021 guidelines, inform all sexually active adult and adolescent individuals about HIV pre-exposure prophylaxis.
B
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  • Post-exposure prophylaxis

7.Follow-up and surveillance

Follow-up sexually transmitted infection screening: perform quarterly screening for asymptomatic STIs in patient populations with high rates of bacterial STIs and incomplete condom use.
B

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  • Follow-up viral load monitoring

  • Follow-up CD4 cell count monitoring

  • Linkage to care and adherence monitoring