HIV/AIDS: An Update ________________________________________________________________________
determination about the nPEP is recommended when the HIV infection status of the source of the body fluids is unknown, and the reported exposure presents a substantial risk for trans- mission if the source did have HIV infection. All persons offered nPEP should be prescribed a 28-day course of a three-drug antiretroviral regimen. The preferred regimen for otherwise healthy adults and adolescents is tenofovir disoproxil fumarate (300 mg) with emtricitabine (200 mg) once daily plus raltegravir 400 mg twice daily or dolutegravir 50 mg daily. All persons evaluated for possible nPEP should be provided any indicated prevention, treatment, or supportive care for other exposure-associated health risks and conditions (e.g., bacterial sexually transmitted infections, traumatic injuries, hepatitis B virus and hepatitis C virus infection, or pregnancy). All persons who report behaviors or situations that place them at risk for frequently recurring HIV exposures (e.g., injection drug use, sex without condoms) or who report receipt of a course of nPEP in the past year should be provided risk-reduction counseling and intervention services, including consideration of pre-exposure prophylaxis.
Following the host immune response, coincident with sero- conversion and the rise in CD8 cytotoxic T cells, the viral load decreases steadily, reaching a relatively stable level at about six months. At this juncture, the degree of viral load correlates with the subsequent pace of disease progression. Patients hav- ing the highest viral load, exhibit the most rapid progression to AIDS. As a result of the ongoing, protracted infection of target lymphocytes, the CD4 count gradually declines over time in the absence of treatment, at an average annual rate of about 50 cells/mcL [11]. ASYMPTOMATIC HIV INFECTION Approximately 10% to 20% of individuals with newly acquired HIV are asymptomatic during the initial two months follow- ing acute infection [11; 12]. While initial routine laboratory studies are relatively normal, serologic and virologic studies are positive and these patients show the same host-virus dynamics, including gradual decline in CD4 count, as seen in symptomatic patients. The serologic diagnosis of HIV infection in an asymptomatic patient does not, in and of itself, establish how recently the patient became infected. The stage of infection may be esti- mated on the basis of careful history and physical examination, and a standard laboratory evaluation that includes complete blood counts, lymphocyte subsets or CD4 count, and viral load. The duration of this asymptomatic stage is variable depending on prevailing CD4 count and viral load and is amenable to treatment with antiretroviral therapy (ART) [11]. PERSISTENT GENERALIZED LYMPHADENOPATHY In the months following acute infection, whether symptomatic or not, many patients have persistent, painless generalized lymphadenopathy (PGL) without other disease manifestations. PGL is defined as palpable lymph node enlargement of 1 cm or greater at two or more extrainguinal sites that persists for more than three months in the absence of a concurrent ill- ness or explanation other than HIV infection. In some cases, lymphadenopathy regresses as HIV disease advances, prob- ably because the architecture of the lymph node is gradually destroyed [11; 12]. CHRONIC HIV AND DISEASE PROGRESSION Chronic, asymptomatic HIV infection with ongoing low- level viral activity may last for many years before eventual progression to AIDS. Symptomatic illness can be expected to supervene as the CD4 count declines to a level less than 200 cells/mcL, as this correlates with severe immunodeficiency. The CDC defines late-stage HIV infection as AIDS on the basis of two criteria: CD4 count less than 200 cells/mcL or a characteristic AIDS-defining illness such as PCP, central nervous system (CNS) toxoplasmosis, or other opportunistic infections or tumors (Kaposi sarcoma). As noted, the WHO defines advanced HIV disease 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 [5].
NATURAL HISTORY AND CLASSIFICATION OF HIV INFECTION
LATENCY PERIOD Clinical latency, sometimes referred to as the window period, is the time elapsed between acquisition of the virus and the body’s immune response sufficient to generate detectable antibody. This latent period is longer for HIV than for most other viral pathogens and is variable among newly infected individuals [11]. ACUTE HIV INFECTION HIV infection is a protracted illness that passes through several stages and, if untreated, is ultimately fatal, with a median sur- vival time from seroconversion of 8 to 10 years [28; 29]. Within 15 to 30 days after acquisition of HIV infection, the majority of patients (50% to 90% in reported series) develop an acute retroviral syndrome similar to infectious mononucleosis [12]. Symptoms include fever, sore throat, malaise, rash, diarrhea, lymphadenopathy, mucocutaneous ulcerations and weight loss averaging 10 pounds. A variety of neurologic syndromes including encephalitis may occur. The illness is self-limited, with an average duration of two to three weeks. Laboratory abnormalities include lymphopenia, atypical lymphocytosis, thrombocytopenia, and a decreased CD4 cell count. During this early phase of clinical illness, HIV antibody tests are often negative and the diagnosis rests on the demonstration of HIV P24 antigen or, preferably, quantitative plasma HIV RNA. Concentrations of HIV RNA in the blood (viral load) are high during the acute syndrome [11].
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MDCT2026
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