Appendix
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Infectious Diseases

HIV-2 Infection

Human immunodeficiency virus (HIV)-2 is an enveloped retrovirus causing human infection, similar to HIV-1, and is primarily endemic to West Africa. Due to globalization and increased migration, HIV-2 has now spread worldwide, with an estimated 1 to 2 million individuals affected. Without treatment, HIV-2 results in significant morbidity and mortality. Clinicians must recognize the distinctions between HIV-1 and HIV-2, particularly in individuals from high-prevalence regions, as prompt diagnosis

v1 · Reviewed Nov 7, 2026 by Automated Clinical Reviewer (Strict Verbatim v1)
  • Clinicians must recognize the distinctions between HIV-1 and HIV-2, particularly in individuals from high-prevalence regions, as prompt diagnosis and management are critical to improving outcomes.
  • clinicians must become familiar with the differences between HIV-1 and HIV-2 while maintaining a high index of suspicion for HIV-2 in persons from endemic regions.
  • Thus, a low threshold should be maintained in sending HIV-2 testing, particularly in patients with epidemiologic risk.
  • Importantly, dual infection with HIV-1 should be ruled out early as part of initial laboratory testing.
  • Many of these limitations have been mitigated by the widespread use of the fourth-generation HIV-1/2 antigen-antibody testing, which includes a differentiation assay.
  • The testing algorithm was revised in 2018 and should be used by all clinicians when interpreting diagnostic testing results for HIV.
  • Resistance testing is also unavailable, and currently, there are no validated HIV-2 genotypic or phenotypic resistance assays approved for clinical use in the US.
  • Currently, it is recommended that all patients diagnosed with HIV-2 be started on ART as soon as possible after diagnosis.
  • The first line of recommended treatments includes combining 2 nucleoside reverse transcriptase inhibitors (NRTIs) plus an integrase strand transfer inhibitor or 2 NRTIs plus a boosted protease inhibitor with either darunavir or lopinavir.
  • HIV-2 has intrinsic drug resistance to all non-nucleoside reverse transcriptase inhibitors, rendering them ineffective.
  • In addition, most protease inhibitors are ineffective except for darunavir, lopinavir, and saquinavir.
  • The fusion inhibitor enfuvirtide also has no HIV-2 activity and should not be used.
  • Although there is no data specifically from HIV-2 patient cohorts, the same primary prophylaxis is recommended for those with CD4 counts below 200 cells/µL to prevent opportunistic infection with common pathogens such as Pneumocystis jiroveci and Toxoplasma gondii .
  • Although there are no data explicitly addressing PrEP in preventing HIV-2, the antiretrovirals used for PrEP are active against both HIV-1 and HIV-2, and similarly, high levels of efficacy would be expected.
  • The initial monitoring of patients with HIV-2 should follow the same recommended guidelines set out for patients with HIV-1, except for baseline resistance testing.
  • To determine treatment progress, clinicians can follow CD4 counts and HIV-2 viral loads if available.
  • However, treatment failure should be suspected in patients with undetectable baseline viral loads if disease progression or continued CD4 decline occurs.
  • Once patients with HIV-2 have developed advanced immunosuppression with CD4 cell counts less than 200 cells/µL, they are at risk of developing the same types of opportunistic infections seen in HIV-1.
  • review
    HIV-2 Infection. StatPearls [Internet] — Andrew K. Kapoor, Simi Padival — StatPearls Publishing, 2022

Decision support only. Verify against local protocols and current labeling. Source: www.ncbi.nlm.nih.gov