HIV infection

Last reviewed: 22 Feb 2023
Last updated: 22 Apr 2022



History and exam

Key diagnostic factors

  • fevers and night sweats
  • weight loss
  • skin rashes and post-inflammatory scars
  • oral ulcers, angular cheilitis, oral thrush, or oral hairy leukoplakia
  • diarrhea
  • wasting syndrome
  • changes in mental status or neuropsychiatric function
  • recent hospital admissions
  • tuberculosis (TB)
  • medical comorbidities
  • sexual activity
  • generalized lymphadenopathy
  • Kaposi sarcoma
  • genital STIs
  • chronic vaginal candidiasis
  • shingles
  • headaches
  • periodontal disease
  • retinal lesions on fundoscopy
  • shortness of breath on exertion, cyanosis on exertion, dry cough, silent chest on auscultation
More key diagnostic factors

Other diagnostic factors

  • current and prior use of other substances
  • peripheral neuropathy
  • recurrent herpes simplex
  • hepatomegaly or splenomegaly
  • meningeal signs (bacterial or viral meningitis)
Other diagnostic factors

Risk factors

  • needle sharing with intravenous drug use
  • unprotected receptive anal intercourse
  • unprotected receptive penile-vaginal sexual intercourse
  • percutaneous needle stick injury
  • high maternal viral load (mother-to-child transmission)
  • use of progestin-only injectable contraceptives
  • herpes simplex virus type 2 (HSV-2) infection
More risk factors

Diagnostic investigations

1st investigations to order

  • serum HIV enzyme-linked immunosorbent assay (ELISA)
  • serum HIV rapid test
  • HIV noninvasive tests
  • serum Western blot
  • serum p24 antigen
  • serum HIV DNA polymerase chain reaction (PCR)
  • CD4 count
  • serum viral load (HIV RNA)
  • drug resistance testing
  • pregnancy test
  • serum hepatitis B serology
  • serum hepatitis C serology
  • serum venereal disease research laboratory test
  • Treponema pallidum hemagglutination test
  • rapid plasma reagin
  • tuberculin skin test
  • CBC with differential
  • serum electrolytes
  • serum creatinine
  • urinalysis
More 1st investigations to order

Investigations to consider

  • chest x-ray
  • liver function tests (LFTs)
  • random or fasting lipid profile
  • random or fasting plasma glucose
  • hepatitis A serology (IgG)
  • toxoplasma serology (IgG)
  • gonorrhea and chlamydia testing
  • human leukocyte antigen-B*5701 testing
More investigations to consider

Treatment algorithm


newly confirmed infection


virologic or immunologic treatment failure



Chad J. Achenbach, MD, MPH

Associate Professor of Medicine

Infectious Diseases

Northwestern Medicine

Feinberg School of Medicine, Northwestern University




CJA has received funds for lecturing at educational events and reimbursement for travel to these lectures by ViiV pharmaceuticals. CJA has been paid for service on a Data Safety Monitoring Board by ABIVAX.


Dr Chad J. Achenbach would like to gratefully acknowledge Dr Richard Rothman, Dr Michael Ehmann, Dr Linda-Gail Bekker, Dr Catherine Orrell, and Dr Lisa Capaldini, the previous contributors to this topic.


ME, LGB, and CO declare that they have no competing interests. RR attended a symposium/conference hosted by a funding agency, Gilead HIV FOCUS program, from which he receives research funds. RR pays staff for an implementation/research program grant from Gilead HIV FOCUS for development of HIV testing programs in Emergency Departments. LC is on the speakers' bureau for the following pharmaceutical companies: GlaxoSmithKline, BMS, Merck, Gilead, Roche, Pfizer, Solvay, Lilly, Serrano, and Tibotec.

Peer reviewers

Marianne Harris, MD

Clinical Assistant Professor

University of British Columbia




MH is a member of an advisory board and/or speakers' bureau for Gilead Sciences Canada Inc, Merck Canada Inc, and ViiV Healthcare.

William Rodriguez, MD

Assistant Professor of Medicine

Harvard Medical School

Director of Research

Global Health Delivery Project

Harvard School of Public Health




WR declares that he has no competing interests.

Jeremy Day, BChir, MB

Infectious Disease Physician

Oxford University Clinical Research Unit

Hospital for Tropical Diseases

Ho Chi Minh City



JD declares that he has no competing interests.

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