Overview of HIV

Related Diseases & Conditions

• HIV infection

  Summary

  HIV infection is caused by a retrovirus that infects and replicates in human lymphocytes and macrophages, eroding the integrity of the human immune system over a number of years, culminating in immune deficiency and a susceptibility to a series of opportunistic and other infections as well as the development of certain malignancies. Globally, an estimated 38.4 million people were living with HIV at the end of 2021, with 1.5 million people newly infected.[3]​ Most people are infected through sexual contact, before birth or during delivery, during breast-feeding, or when sharing contaminated needles and syringes.
• HIV infection in pregnancy

  Summary

  Pregnancy in women living with HIV is complicated not only by HIV infection itself but also by the medical and psychosocial comorbidities associated with HIV. HIV infection in pregnancy poses a threat to maternal immune health and can lead to perinatal transmission of HIV in utero, intrapartum, or through breastfeeding postnatally.
• Post-exposure HIV prophylaxis

  Summary

  The administration of antiretroviral therapy to HIV-negative people who may have been occupationally or sexually exposed to HIV. Once exposed to HIV, there may be a brief period before the infection is established, during which antiretroviral therapy may successfully prevent viral replication.[4] [5]
• HIV-related opportunistic infections

  Summary

  Infections that can occur as a result of impaired cell-mediated immunity in advanced stages of HIV infection. These illnesses tend to occur most often in patients who have untreated HIV infection or who fail to respond to antiretroviral therapy. Tuberculosis, Pneumocystis jirovecii pneumonia, candidiasis, cryptococcosis, toxoplasmosis, cytomegalovirus, Mycobacterium avium complex, and coccidioidomycosis infections are among the HIV-related opportunistic infections often encountered in clinical practice.
• Pneumocystis jirovecii pneumonia

  Summary

  Historically one of the most common AIDS-defining illnesses in children, adolescents, and adults in high-income countries.[6] It is an infection of the lung caused by the fungal organism Pneumocystis jirovecii (formerly known as Pneumocystis carinii). Typically, it causes clinical disease in severely immunocompromised patients, such as HIV-positive patients with CD4 cell counts <200 cells/microliter, hematopoietic cell transplant patients, solid-organ transplant patients, or patients on chronic immunosuppressive therapy.
• Pulmonary tuberculosis

  Summary

  An infectious disease caused by Mycobacterium tuberculosis. In many patients, M tuberculosis becomes dormant before it progresses to active tuberculosis. It most commonly involves the lungs and is communicable in this form, but may affect almost any organ system including the lymph nodes, central nervous system, liver, bones, genitourinary tract, and gastrointestinal tract. TB is particularly devastating in areas with high prevalence of HIV infection.[7] The WHO estimates there were 187,000 TB-related deaths among people with HIV in 2021.[8]​
• Mycobacterium avium complex

  Summary

  Mycobacterium avium complex (MAC), also known as Mycobacterium avium-intracellulare (MAI), consists of 2 mycobacterium species, M avium and M intracellulare. It traditionally causes 3 disease syndromes: pulmonary disease, cervical lymphadenitis, and disseminated disease. People living with HIV with a CD4 count <50 cells/microliter are at increased risk of infection.[9]​
• Toxoplasmosis

  Summary

  Caused by the protozoan parasite Toxoplasma gondii. Cats are the definitive hosts for the parasite. Humans are intermediate hosts, and become infected by ingesting uncooked meat infected with tissue cysts (bradyzoites), by ingestion of other food or water contaminated with oocysts, or by transplacental spread of tachyzoites.[10]​ Infection in humans is lifelong and often asymptomatic, unless a patient becomes immunosuppressed.
• Cryptococcosis

  Summary

  An opportunistic fungal infection caused by Cryptococcus species. Cryptococcus neoformans var. grubii and Cryptococcus neoformans cause morbidity and mortality, especially in immunosuppressed populations. Patients with HIV and CD4 count of <100 cells/microliter are at highest risk of infection. Cryptococcal meningitis is estimated to cause 15% of all AIDS-related deaths globally.[11]
• Cytomegalovirus infection

  Summary

  Cytomegalovirus (CMV) is a ubiquitous beta-herpes virus that infects the majority of humans. Primary infection in individuals with normal immune function is usually asymptomatic. After primary infection, CMV establishes a state of lifelong latency in various host cells, with periodic subclinical reactivations that are controlled by a functioning immune system. When reactivation (or primary infection) occurs in patients with severely compromised immune function (transplant patients, or patients with AIDS with a CD4 count <50 cells/microliter), uncontrolled CMV replication often ensues, which leads to the clinical manifestations characterized by fever, bone marrow suppression, and tissue-invasive disease.[12]
• Oral candidiasis

  Summary

  A local infection of oral tissues by yeasts of the genus Candida, mostly C albicans. Seen most frequently in association with local and systemic immunologic suppression. Although Candida are considered normal flora in the gastrointestinal and genitourinary tracts in humans, they are capable of local infection of mucus membranes (oropharyngeal candidiasis, esophagitis, vulvovaginitis), focal invasion (endophthalmitis, meningitis, endocarditis), and dissemination (candidemia).
• Kaposi sarcoma

  Summary

  One of the most common cancers arising in people with HIV. It is a low-grade vasoformative neoplasm associated with human herpesvirus-8 (HHV-8, also known as Kaposi sarcoma-associated herpesvirus).[13] Lesions frequently involve mucocutaneous sites, but may become more extensive to involve the lymph nodes and visceral organs. Skin lesions evolve from an early patch, to a plaque, and later to ulcerating tumor nodules.
• Evaluation of dermatologic disorders in HIV

  Summary

  In the early phases of the HIV epidemic, skin disease was frequently a presenting manifestation of the infection.[14]​ Cutaneous manifestations often reflect immune status and may offer insight into the long-term prognosis. The etiologies of different diseases involving the skin and HIV vary. Some skin diseases are fairly specific to HIV. Other skin diseases may appear in non-HIV-infected populations but have altered presentations in those with HIV.
• Evaluation of HIV-related mental status changes

  Summary

  Causes of altered mental status in HIV infection include both acutely presenting conditions (which often represent HIV-related opportunistic infection or associated systemic illness) and more progressive neurocognitive disease or psychological comorbidity. Neuropsychological issues may arise as a direct effect of HIV infection: for example, as part of a spectrum of HIV-associated neurocognitive disorders or as a psychiatric comorbidity (e.g., depression or alcohol/substance abuse).