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- HIV is a retrovirus (subgroup lentivirus) that integrates into CD4 T-lymphocytes, altering cell-mediated immunity and causing cell death, severe immunodeficiency, opportunistic infections, and malignancies if not treated.
- The natural history of untreated HIV infection includes viral transmission, acute retroviral syndrome, recovery and seroconversion, asymptomatic chronic HIV infection, and symptomatic HIV infection or AIDS.
- Without treatment, the average patient progresses to AIDS ~10 years after acquiring the virus.
- HIV-infected persons with CD4 <200 cells/mm3 or with AIDS-defining illnesses are categorized as living with AIDS.
Etiology and Pathophysiology
- HIV primarily infects CD4+ cells. HIV is a single-stranded, positive-sense, enveloped RNA virus. After entering target cells, viral RNA is transcribed to DNA (through the process of reverse transcription), imported to the host cell nucleus and encoded into the host DNA. The virus can become latent or produce new viral RNA with proteins that are released to infect other CD4+ cells. Host CD8+ cells are activated as part of the seroconversion response.
- There are two types of HIV. HIV-1 was first described and is more virulent, causing the majority of HIV infections worldwide. HIV-2 is less infective and seen primarily in West Africa.
- Sexual activity (70% of transmission): Ulcerative urogenital lesions promote transmission.
- Injection drug use
- Children of HIV-infected women
- Maternal HIV-1 RNA level predicts transmission.
- HIV can also be transmitted in breast milk. HIV+ women should not breastfeed their infants unless there is no other alternative. In this case, consider antiretroviral therapy (ART) (2).
- Recipients of blood products prior to 1985
- Occupational exposure (health care workers)
- Avoid unprotected, high-risk sex and intravenous drug use, particularly with shared needles.
- Preexposure prophylaxis (PrEP) is recommended by WHO for persons at high risk of acquiring HIV.
- General guidelines for PrEP: (i) exclude acute or chronic HIV infection before initiating therapy, (ii) repeat HIV testing every 3 months during therapy, (iii) renal function testing at baseline and every 6 months
- PrEP should be started within 72 hours of exposure and continued for 28 days with a three-drug regimen (1).
Commonly Associated Conditions
- Syphilis more aggressive in HIV-infected persons
- Tuberculosis (TB) is coepidemic with HIV; test all for TB. Dually infected (TB and HIV) have 100 times greater risk of developing active TB.
- Patients coinfected with hepatitis C or hepatitis B have a more rapid progression to cirrhosis.
- Increased risk for cervical cancer, lymphoma, and skin malignancies