AIDS: Definition, and Treatment

AIDS

Acquired Immunodeficiency Syndrome (AIDS) represents the most advanced stage of infection caused by the Human Immunodeficiency Virus (HIV). It is a chronic, life-threatening condition characterized by a profound weakening of the immune system, which renders the body highly susceptible to opportunistic infections, malignancies, and neurological complications. Since its emergence in the early 1980s, AIDS has evolved into one of the most pressing public health challenges worldwide, though tremendous progress has been made in its treatment and prevention.

2. Definition

AIDS is defined as a clinical syndrome resulting from a progressive decline in CD4+ T-lymphocytes due to chronic HIV infection. It is characterized by:

• CD4+ cell count <200 cells/μL, or
• Presence of AIDS-defining illnesses such as Pneumocystis jirovecii pneumonia, Kaposi’s sarcoma, or tuberculosis, among others.

3. Epidemiology of AIDS

3.1 Global Overview

• As per UNAIDS 2023, approximately 39 million people were living with HIV globally.
• Over 28.7 million people were accessing antiretroviral therapy (ART).
• Since the beginning of the epidemic, more than 84 million have been infected, and around 40 million have died.

3.2 Regional Distribution

• Sub-Saharan Africa carries the highest burden (about two-thirds of global HIV cases).
• South and Southeast Asia, Eastern Europe, and Latin America are also significantly affected.

3.3 India Scenario

• As per NACO (National AIDS Control Organization), about 2.4 million people are living with HIV in India.
• The epidemic in India is concentrated among high-risk groups like sex workers, men who have sex with men (MSM), and people who inject drugs (PWID).

4. Etiology and Causes

4.1 Causative Agent: HIV

Human Immunodeficiency Virus (HIV) is a retrovirus belonging to the family Retroviridae and genus Lentivirus. There are two main types:

• HIV-1: Most common and virulent worldwide.
• HIV-2: Less transmissible, mostly confined to West Africa.

4.2 Structure of HIV

• Enveloped virus with two copies of single-stranded RNA.
• Key enzymes: reverse transcriptase, integrase, and protease.
• Target cells: CD4+ T-cells, macrophages, and dendritic cells.

5. Mode of Transmission

HIV is transmitted via:

1. Sexual Contact – Unprotected vaginal, anal, or oral sex.
2. Blood and Blood Products – Transfusion, needle-sharing among drug users.
3. Perinatal Transmission – From infected mother to child during pregnancy, delivery, or breastfeeding.
4. Healthcare-Associated Exposure – Needle-stick injuries or contaminated instruments.

It is not transmitted by casual contact, hugging, kissing, sharing food, or mosquito bites.

Pathophysiology of AIDS

Step 1: Entry of HIV Virus

AIDS is caused by the Human Immunodeficiency Virus (HIV). The virus enters the body through blood, sexual contact, or from mother to child. Once inside, it targets immune cells, mainly CD4+ T-helper cells.

Step 2: Attachment and Entry into Cells

The virus uses special proteins (gp120 and gp41) on its surface to attach to the CD4 receptor and co-receptors (CCR5 or CXCR4) on T-helper cells. After attachment, the virus enters the cell.

Step 3: Viral Replication Inside Cells

Inside the cell, HIV releases its RNA. Using an enzyme called reverse transcriptase, it makes a DNA copy of its RNA. This viral DNA enters the host cell’s nucleus and joins the human DNA with the help of another enzyme called integrase. From there, the virus uses the host cell machinery to make new viral proteins and particles.

Step 4: Destruction of CD4+ T Cells

As HIV multiplies, many CD4+ T cells are destroyed either directly by the virus or by the immune system. This leads to a gradual fall in CD4 count, weakening the immune defense of the body.

Step 5: Progressive Immune System Failure

With fewer CD4+ T cells, the body cannot coordinate an effective immune response. This makes the person vulnerable to opportunistic infections (like tuberculosis, fungal infections) and some cancers (like Kaposi’s sarcoma, lymphoma).

Step 6: Development of AIDS

When the CD4 count drops below 200 cells/µL (or when serious opportunistic infections or cancers develop), the patient is said to have AIDS. At this stage, even minor infections can become life-threatening.

How to Prevent HIV Infection

1. Practice Safe Sex

• Use condoms correctly every time you have vaginal, anal, or oral sex.
• Avoid unprotected sex with partners whose HIV status is unknown.
• Use water- or silicone-based lubricants with condoms (especially for anal sex) to reduce the risk of condom breakage.

2. Get Tested Regularly

• Know your own HIV status and your partner’s.
• Encourage HIV testing in relationships, especially new or multiple partners.
• Early diagnosis helps prevent unintentional transmission.

3. Avoid Sharing Needles

• Do not share needles or syringes for drugs, tattoos, or piercings.
• Always use new, sterile equipment.
• Needle-exchange programs can help reduce risk in some communities.

Ensure Blood Safety

• Only receive blood transfusions from licensed, screened sources.
• In clinics or hospitals, make sure that injections, surgical tools, and dental instruments are sterile.

6. Pathogenesis of AIDS

1. Entry: Virus enters via mucosal surfaces or directly into bloodstream.
2. Attachment: gp120 on HIV binds to CD4 receptor and co-receptors (CCR5/CXCR4) on T-cells.
3. Reverse Transcription: Viral RNA is converted to DNA.
4. Integration: Viral DNA integrates into host genome via integrase enzyme.
5. Latency: The virus may remain dormant or start replicating.
6. Destruction of CD4+ Cells: Leads to immune suppression, making the host vulnerable to opportunistic infections.

7. Stages of HIV Infection (Types/Phases)

Stage 1: Acute HIV Infection

• Occurs 2–4 weeks after exposure.
• Characterized by flu-like symptoms: fever, sore throat, rash, lymphadenopathy.
• High viral load and extreme infectivity.

Stage 2: Clinical Latency (Chronic HIV)

• Virus continues replicating at low levels.
• Asymptomatic or mild symptoms may appear.
• May last for several years to over a decade without treatment.

Stage 3: AIDS

• CD4+ count drops below 200 cells/μL.
• Appearance of AIDS-defining illnesses:
  • Pneumocystis jirovecii pneumonia
  • Kaposi’s sarcoma
  • Tuberculosis
  • Cytomegalovirus retinitis
  • Toxoplasmosis of the brain
• Without treatment, survival is typically less than 3 years.

8. Clinical Manifestations

Acute HIV Symptoms

• Fever, headache, rash, sore throat
• Myalgia, diarrhea
• Oral/genital ulcers

Chronic Phase Symptoms

• Persistent generalized lymphadenopathy
• Weight loss
• Night sweats
• Recurrent oral candidiasis
• Diarrhea
• Neurological manifestations (HIV dementia, peripheral neuropathy)

AIDS-Defining Conditions

• Recurrent bacterial pneumonia
• Cervical cancer
• Extrapulmonary cryptococcosis
• Kaposi’s sarcoma
• CNS toxoplasmosis
• Tuberculosis

9. Diagnosis of AIDS

9.1 Screening Tests

• Rapid antibody tests (ELISA, lateral flow): Detect HIV-1 and HIV-2 antibodies.
• Fourth-generation tests: Detect both antibodies and p24 antigen.

9.2 Confirmatory Tests

• Western Blot or Immunofluorescence Assay
• Nucleic Acid Tests (NATs): Detect viral RNA for early diagnosis and monitoring.

9.3 Monitoring Tests

• CD4+ T-cell count: Measures immune status.
• Viral load testing (RT-PCR): Quantifies HIV RNA to assess treatment response.

10. Treatment of AIDS

10.1 Antiretroviral Therapy (ART)

ART refers to the use of a combination of antiretroviral drugs (ARVs) to suppress HIV replication and restore immune function. It is the mainstay of HIV/AIDS treatment.

Goals of ART

• Reduce HIV viral load to undetectable levels.
• Prevent progression to AIDS.
• Reduce transmission risk.
• Improve quality and longevity of life.

10.2 Classes of Antiretroviral Drugs

1. Nucleoside/Nucleotide Reverse Transcriptase Inhibitors (NRTIs)
   • E.g., Zidovudine (AZT), Lamivudine (3TC), Tenofovir (TDF), Abacavir (ABC)
   • Mechanism: Inhibit reverse transcriptase and block viral DNA synthesis.
2. Non-Nucleoside Reverse Transcriptase Inhibitors (NNRTIs)
   • E.g., Efavirenz (EFV), Nevirapine (NVP), Etravirine
   • Bind to reverse transcriptase enzyme and inhibit its function.
3. Protease Inhibitors (PIs)
   • E.g., Lopinavir/ritonavir, Atazanavir, Darunavir
   • Prevent viral polyprotein cleavage, blocking maturation of new virions.
4. Integrase Strand Transfer Inhibitors (INSTIs)
   • E.g., Dolutegravir (DTG), Raltegravir, Bictegravir
   • Inhibit viral DNA integration into host genome.
5. Entry/Fusion Inhibitors
   • E.g., Enfuvirtide, Maraviroc
   • Block entry of HIV into CD4+ cells.

10.3 Recommended First-Line Regimens (as per WHO and NACO)

• TDF + 3TC + DTG (Tenofovir + Lamivudine + Dolutegravir): Preferred due to high potency, fewer side effects, and higher barrier to resistance.
• For pregnant women: Regimens are adjusted for safety.
• ART is now started irrespective of CD4 count, as soon as HIV is diagnosed (“Test and Treat” strategy).

10.4 Treatment of Opportunistic Infections

10.5 Prophylaxis for Opportunistic Infections

• Cotrimoxazole prophylaxis when CD4 < 200 cells/μL
• Isoniazid Preventive Therapy (IPT) for TB
• Fluconazole for fungal infections in advanced cases

10.6 HIV Prevention Strategies

• Safe sex practices: Condom use, education
• Pre-exposure prophylaxis (PrEP): Tenofovir + Emtricitabine for high-risk individuals
• Post-exposure prophylaxis (PEP): Within 72 hours of exposure
• Screening and treatment of STDs
• Needle exchange programs
• Mother-to-child transmission (MTCT) prevention: ART in pregnancy, safe delivery, and feeding practices

11. Prognosis

• With early and sustained ART, life expectancy approaches that of the general population.
• Factors improving prognosis:
  • Early diagnosis and linkage to care
  • Adherence to ART
  • Good nutritional and psychosocial support

12. Social and Psychological Aspects

• Stigma and discrimination remain significant barriers to care.
• Mental health support is essential due to high rates of depression, anxiety, and substance abuse.
• Community education, destigmatization, and support groups play key roles.

Myth and facts

MYTH 1: You can get HIV/AIDS through casual contact like hugging, shaking hands, or sharing utensils.

Fact: HIV is not spread through casual contact. It is transmitted through specific body fluids: blood, semen, vaginal fluids, rectal fluids, and breast milk. Hugging, kissing, sharing food, using the same toilet, or insect bites do not transmit HIV.

MYTH 2: Only certain groups of people (like gay men or drug users) get HIV/AIDS.

Fact: HIV can infect anyone, regardless of gender, sexual orientation, age, or background. Risk is based on behavior, not identity. Unprotected sex, sharing needles, or unsafe medical practices increase the risk.

MYTH 3: HIV/AIDS is a death sentence.

Fact: With modern antiretroviral therapy (ART), people with HIV can live long, healthy lives. Early diagnosis and consistent treatment help control the virus and prevent progression to AIDS.

MYTH 4: You can tell if someone has HIV just by looking at them.

Fact: A person with HIV can look perfectly healthy for years. The only way to know is through HIV testing. Regular testing is important for prevention and early treatment.

MYTH 5: HIV-positive mothers will always pass the virus to their babies.

Fact: With proper medical care during pregnancy, childbirth, and breastfeeding, the risk of mother-to-child transmission can be reduced to less than 1%. Antiretroviral Therapy (ART) is highly effective in preventing transmission.

MYTH 6: There is a cure for HIV/AIDS.

Fact: There is currently no cure for HIV, but it can be effectively managed with medication. Scientists are working on potential cures and vaccines, but as of now, Antiretroviral Therapy (ART) is the best treatment.

MYTH 7: HIV can be spread through mosquito bites.

Fact: Mosquitoes do not transmit HIV. The virus cannot survive or reproduce inside insects. HIV is a human-specific virus and requires specific routes of transmission.

Conclusion

AIDS, caused by HIV, is a complex, multifaceted disease that has evolved from a fatal diagnosis into a manageable chronic illness, thanks to advances in antiretroviral therapy. Despite the scientific progress, prevention, awareness, early detection, and universal access to treatment remain paramount in the fight against HIV/AIDS. Continuous education, robust healthcare systems, and social acceptance are vital in curbing the epidemic and achieving the goal of “Ending AIDS as a public health threat by 2030.”