HIV/AIDS: An Update ________________________________________________________________________
Chronic HIV disease follows a variable course but eventually leads to a variety of clinical manifestations, some of which are directly related to the impact of chronic infection on vital organs. Common syndromes include HIV encephalopathy and dementia, peripheral neuropathy, interstitial nephropathy, a variety of skin eruptions, and signs of adrenal insufficiency. The late clinical manifestations of HIV disease are most fre- quently the result of acquired immunodeficiency syndrome (AIDS) that follows progressive depletion of CD4+ T lympho- cytes to levels <200 cells/mcL. AIDS-defining illnesses include secondary, opportunistic infections and certain malignan- cies usually encountered only in clinical settings of severely impaired cellular immunity. Opportunistic infections are very common in persons with undiagnosed or poorly treated chronic HIV infection and are of two types. The first type is infection newly acquired by exposure to micro-organisms normally nonpathogenic, or of low pathogenicity, for persons with a healthy immune system. Examples are Pneumocystis jiroveci , Cryptococcus neoformans , Histoplasma capsulatum , and atypical mycobacteria, all of which are commonly associated with inhalational exposures and tran- sient colonization of the respiratory tract in healthy individuals. The second type is reactivation of latent infection acquired earlier in life, which typically remains dormant throughout life. Examples of this type are CMV, Toxoplasma gondii , Myco- bacterium tuberculosis , and Histoplasma capsulatum . The advent of an opportunistic infection may serve as the herald sign of unrecognized, undiagnosed chronic HIV infection/AIDS [5]. Clinically, these infections tend to present in one of several distinct syndromes, with useful differential diagnosis consid- erations: • Pneumonia: Pneumocystis pneumonia (PCP), Mycobacterium avium complex (MAC), cryptococcosis, histoplasmosis • Meningoencephalitis: Toxoplasmosis, cryptococcosis, tuberculosis • Gastrointestinal disease (diarrhea): Common bacterial dysentery, cryptosporidium, fungal and atypical mycobacterial infection • Fever of unknown origin (often with abdominal complaints, hepatosplenomegaly, and/or lymphadenopathy): CMV, MAC, tuberculosis, histoplasmosis Late clinical manifestations related to HIV-induced malignancy include Kaposi sarcoma of the skin or respiratory tract and lymphoma presenting as lymphadenopathy, splenomegaly, or focal gastrointestinal disease. Without satisfactory antiretroviral therapy, the usual patient with HIV/AIDS experiences a slow, inexorable wasting illness punctuated by periods of feverishness and diarrhea, becoming increasingly anorectic, malnourished, and lethargic. Late clini- cal signs include muscle wasting and weakness, anemia and thrombocytopenia, lymphadenopathy, pulmonary infiltrates,
and neurologic abnormalities (such as dementia, peripheral neuropathy, and tremors). Advanced HIV disease is defined by the WHO as a CD4 count <200 cells/mcL in adults and adolescents, or HIV infection regardless of count in any child younger than 5 years of age. The median survival of adult and adolescent patients with advanced HIV is approximately 12 to 18 months. Patients succumb to complications of uncontrolled infection, malignancy, or criti- cal organ failure (such as uremia or adrenal insufficiency) [5]. HIV TESTING There are several recommendations for HIV screening. The U.S. Preventive Services Task Force (USPSTF) and the Agency for Healthcare Research and Quality (AHRQ) recommend screening for HIV infection in all adolescents and adults 15 to 65 years of age, younger adolescents and older adults at increased risk, and all pregnant women, while the CDC rec- ommends being tested for HIV as part of routine healthcare at least once for anyone 13 to 64 years of age [13; 14]. In addi- tion, the OraQiuck HIV self-test was approved by the FDA in 2012 for individuals 17 years of age and older, and in 2024, the age was expanded to include individuals 14 years of age and older [46]. The initial testing for HIV generally consists of an FDA- approved, fourth-generation antigen/antibody combination immunoassay that detects HIV-1 and HIV-2 antibodies and HIV-1 p24 antigen to identify both established and acute infec- tions [15]. If this test is reactive, repeat testing is recommended to differentiate HIV-1 antibodies from HIV-2 antibodies. If this second test is non-reactive, testing with an FDA-approved HIV-1 nucleic acid test is indicated [15]. It is important to note that HIV-2 is not reliably identified by usual immunoblot antibody tests. Additional testing specific to HIV-2 should be considered if HIV-1 test results are atypical or inconsistent with clinical findings, especially for persons from West Africa [2]. Other available tests, including enzyme-linked immunosorbent assay, may be used if the preferred combination immunoassay is not available. The HIV-1 Western blot and HIV-1 immu- nofluorescence assay, previously recommended to make a laboratory diagnosis of HIV-1 infection, are no longer part of the recommended testing algorithm [15]. TRANSMISSION OF HIV HIV is transmitted person-to-person across mucosal or cutane- ous barriers by exposure to infected genital secretions or blood and blood products. The common modes of transmission are sexual intercourse, injection drug use, infusion of blood products, and perinatal transmission. The risk from whole blood, packed cell, and fresh frozen plasma is, at present, extremely low by virtue of more sensitive crossmatching and screening techniques.
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MDCT2026
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