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Acquired Immunodeficiency Syndrome (AIDS)

Overview

Acquired Immunodeficiency Syndrome (AIDS) is caused by Human Immunodeficiency Virus (HIV). It is the most severe form of HIV infection in which the body’s immune system collapses, and the infected person succumbs to opportunistic (which can otherwise be non-lethal) infections. There is currently no effective cure for the disease. Once people get HIV, they have it for life. But with proper medical care, it can be controlled. Without treatment, the survival rate is only three years.

The natural host for the virus in humans. The causative organism, HIV, is an RNA retrovirus. It uses an enzyme (reverse transcriptase) to convert RNA into DNA inside host cells after binding with an immune system called CD4-T helper cells. The antibody response generated in the human body after the virus binds with immune cells is insufficient to neutralize the virus. There are two variants of the virus, HIV-1, and HIV-2 that cause infections worldwide. HIV-1 causes more infections, and both are sexually transmitted.

Cause

The disease is mainly transferred sexually (through vaginal or anal sex but not oral sex). Other ways of transmission are:

  • Through contaminated blood transfusions
  • Needlestick injuries.
  • Sharing needles for drug use.
  • Perinatal transmission from infected mother to the baby.

Types

There are three stages of the disease. People who don’t seek treatment typically progress to the third stage of the disease. With the advancement in medicine, progression to AIDS is less common today than early days. These stages are:

  • Acute HIV Infection
  • Chronic HIV Infection
  • Acquired Immunodeficiency Syndrome (AIDS)

In the acute phase, people have large amounts of virus in their blood and usually develop flu-like symptoms due to the body’s natural response to the virus.

Chronic HIV is also called asymptomatic HIV infection. The latency period in which the virus levels in the blood are deficient. People don’t have any symptoms but can transmit HIV at this stage. With prompt diagnosis and active intervention, progression to the third stage (AIDS) can be stopped.

The third stage is the most severe form of HIV, also called AIDS. The viral load in this stage is very high, and people are highly infectious.

Signs and Symptoms

Initial infection is asymptomatic in 10-60% of cases. Acute HIV occurs four weeks after exposure to the virus. Symptoms include:

In the third, more severe stage, symptoms develop from opportunistic infections but not AIDS. Some rare HIV features include:

Diagnosis

Older tests for AIDS are antibody tests (ELISA). These are less specific and give many false-positive results. Another antibody test is the Western blot, which is more precise when ELISA is positive.

Current CDC recommendations suggest combination tests; antigen/antibody tests, also called 4th generation tests. These tests for p24 antigen and HIV antibodies are more specific and accurate. If 4th generation tests are positive, HIV1 and HIV2 differentiation assay is performed.

For the diagnosis of AIDS, CD4 count is an important marker. It must be less than 200/mm3.

Differential Diagnosis

The symptoms of acute HIV infection resemble mononucleosis caused by Epstein-Barr Virus (EBV). The signs or symptoms of other opportunistic infections should be probed for AIDS, as the two can co-exist. Some of these infections include:

  • Pneumocystis pneumonia
  • Kaposi sarcoma
  • CMV retinitis
  • Candidiasis
  • Burkitt Lymphoma
  • Herpes Simplex
  • Toxoplasmosis
  • Cryptococcus meningitis
  • Thrush (caused by Candida) otherwise healthy individuals should constantly be probed for AIDS

Treatment

People who have tested positive should take care for HIV to reduce the risk of transmission to others. They should take their medication timely and disclose to their sexual partners about the disease and educate them about pre-exposure prophylaxis of the disease. It is important to practice safe sex using condoms after HIV infection. Getting tested and treated for other STDs is also of prime importance.

There is no effective treatment for AIDS. Older guidelines were based on CD4 counts less than 500/mm3 to start treatment, but newer guidelines recommend treating all patients. Multidrug combinations are used for the treatment with Highly Active Retroviral Therapy, also called HAART. The regimen needs to be altered after regular intervals as the drugs can cause gene mutations.

Medication

HIV drugs can be broadly categorized into:

  • Protease inhibitors such as Amprenavir, Darunavir, Fosamprenavir, Nelfinavir, Indinavir, Tipranavir, etc. 
  • Nucleoside reverse transcriptase inhibitors such as Abacavir, Emtricitabine, Lamivudine, Tenofovir, Zidovudine, Stavudine, etc.
  • Non-nucleoside reverse transcriptase inhibitors such as Delavirdine, Etravirine, Efavirenz, Nevirapine, Doravirine, Cabotegravir, etc.
  • Fusion Inhibitors such as Enfuvirtide. 
  • Cellular Chemokine receptor anatagonists like Maraviroc.
  • Entry Inhibitors like Ibalizumab. 
  • Integrase Inhibitors such as Dolutegravir, Elvitegravir. 
  • gp120 attachment inhibitors like Fostemsavir. 
  • Antiretroviral Combination products (reduce the chances of drug resistance)

Prevention

  • Individuals at risk, such as healthcare workers, social workers, and sex workers, should get tested at least once or more.
  • Get tested for STDs and practice safe sexual methods such as condoms.
  • Don’t inject drugs with shared needles into the body.
  • Educate at-risk individuals about pre-exposure and post-exposure prophylaxis. If you have been exposed to the virus, post-exposure prophylaxis within 72 hours can prevent HIV infection.

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