The human immunodeficiency virus (HIV) is an enveloped retrovirus that contains 2 copies of a single-stranded RNA genome. It causes the acquired immunodeficiency syndrome (AIDS) that is the last stage of HIV disease. Two to four weeks after HIV enters the body, the patient may complain of symptoms of primary infection. After that, a long chronic HIV infection occurs, which can last for decades. AIDS is mainly characterized by opportunistic infections and tumors, which are usually fatal without treatment.
The cause of this infectious disease is the human immunodeficiency virus (HIV), which can be classified into HIV-1 and HIV-2. HIV-1 is more globally expanded and virulent. It originated in Central Africa. HIV-2 is much less virulent and comes from West Africa. Both viruses are related antigenically to immunodeficiency viruses found primarily in primates.
The estimated number of people living with HIV/AIDS is 36.7 million worldwide as of 2016. In the United States, a critical risk factor for HIV propagation among young people is the use of drugs before having sex, including marijuana, alkyl nitrites ("poppers"), cocaine, and ecstasy. Other risk factors associated with acquiring HIV infection include men who have sex with men, unsafe sexual practices, the use of intravenous drugs, vertical transmission, and blood transfusions or blood products.
HIV attaches to the CD4 molecule and CCR5 (a chemokine co-receptor); the virus' surface fuses with the cellular membrane, which allows it entry into a T-helper lymphocyte. After integration in the host genome, the HIV provirus forms and then follows transcription and viral mRNA production. HIV structural proteins are made and assembled in the host cell. Viral budding from host cells can release millions of HIV particles that can go to infect other cells.
Benign lymphadenopathy biopsies of HIV patients have shown one of the following morphological patterns:
These histological features relate to the clinical stage of the disease with CD4 counts.
A large number of patients may only have an asymptomatic infection after the exposure. The usual time from exposure to onset of symptoms is 2 to 4 weeks, although, in some cases, it can be as long as 10 months. A constellation of symptoms, known as an acute retroviral syndrome, may appear acutely. Although none of these symptoms are specific to HIV, their presence of increased severity and duration is an indication of poor prognosis. These symptoms, in the order of decreasing frequency, are listed below:
Chronic HIV infection can be characterized by either without AIDS or with AIDS and can progress to advanced HIV infection:
When there is a possibility of acute or early HIV infection, the most sensitive screening immunoassay available (ideally, a combination antigen/antibody immunoassay) in addition to an HIV virologic (viral load) test is performed. RT-PCR based viral load test is favored. A positive HIV virologic test generally indicates HIV infection.
Detectable viremia does not develop until approximately 10 to 15 days after infection, and even the most sensitive immunoassays do not give a positive result until five days after that. Therefore, initial negative immunoassay and virologic tests can be misleading, and if the clinical suspicion for recent HIV exposure is high, repeat testing is done one to two weeks later.
Antiretrovirals are drugs used to treat HIV infections/AIDS, and they are used in various combinations, commonly referred to as highly active retroviral therapy (HAART). The antiretrovirals agent include nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs), NRTI fixed-dose combinations, integrase inhibitors, non-nucleoside reverse transcriptase inhibitors (NNRTIs), protease inhibitors, and CCR5 inhibitors. All patients with HIV, regardless of what level of CD4, should be started on HAART, which is a treatment for life. This therapy has been shown to reduce morbidity and mortality and lower the risk of transmitting the infection to others, as long as they have a low or undetectable viral load.
Single Tablet Regimens
Nucleoside/Nucleotide Reverse Transcriptase Inhibitors (NRTIs)
NRTI Fixed-Dose Combinations
Non-Nucleoside Reverse Transcriptase Inhibitors (NNRTIs)
Patients with HIV and CD4 counts greater than 200, but less than 500 do not have AIDS but can develop chronic infections as well as noninfectious conditions. Diseases such as chronic candidiasis of the mouth or recurrent vaginal candida may occur. Patients may develop severe bouts of herpes simplex or herpes zoster (shingles). Patients are also at a higher risk for cancers that are much more difficult to treat than in healthy people. Patients with normal CD4 counts (greater than 500) tend to have a good quality of life with a lifespan within 4 years of someone without HIV Patients with a CD4 count less than 200 have AIDS and are susceptible to opportunistic infections. They usually have a lifespan of 2 years if they are started on HAART. If these patients are treated with antiretroviral agents and achieve a CD4 count greater than 500, they will have a normal life expectancy.
The prognosis of a patient with HIV and a CD4 count greater than 500 (normal) results in a life expectancy as someone without HIV. A person with untreated AIDS has a life expectancy of about 1 to 2 years after the first opportunistic infection. Antiretroviral treatment can increase CD4 counts and change the patient's status from AIDS to someone with HIV.
A complication of HIV disease is its progression to acquired immunodeficiency syndrome (AIDS). The physician should suspect it once opportunistic infections and/or low CD4 count are present in an individual who is HIV positive.
Principal facts for HIV prevention are patient education, which includes the following:
The management of an HIV-positive patient is complex. It should be carried out by an interprofessional health care team that includes nurses, a social worker, a family doctor, an internal medicine specialist, a pharmacist, and an infectious disease specialist. If an opportunistic infection or a mass develops, the patient should be evaluated by an oncologist and/or surgeon. Psychological support must be provided once the diagnosis of HIV is made.
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