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:
- Sexual Contact – Unprotected vaginal, anal, or oral sex.
- Blood and Blood Products – Transfusion, needle-sharing among drug users.
- Perinatal Transmission – From infected mother to child during pregnancy, delivery, or breastfeeding.
- Healthcare-Associated Exposure – Needle-stick injuries or contaminated instruments.
It is not transmitted by casual contact, hugging, kissing, sharing food, or mosquito bites.
6. Pathogenesis of AIDS
- Entry: Virus enters via mucosal surfaces or directly into bloodstream.
- Attachment: gp120 on HIV binds to CD4 receptor and co-receptors (CCR5/CXCR4) on T-cells.
- Reverse Transcription: Viral RNA is converted to DNA.
- Integration: Viral DNA integrates into host genome via integrase enzyme.
- Latency: The virus may remain dormant or start replicating.
- 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
- 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.
- Non-Nucleoside Reverse Transcriptase Inhibitors (NNRTIs)
- E.g., Efavirenz (EFV), Nevirapine (NVP), Etravirine
- Bind to reverse transcriptase enzyme and inhibit its function.
- Protease Inhibitors (PIs)
- E.g., Lopinavir/ritonavir, Atazanavir, Darunavir
- Prevent viral polyprotein cleavage, blocking maturation of new virions.
- Integrase Strand Transfer Inhibitors (INSTIs)
- E.g., Dolutegravir (DTG), Raltegravir, Bictegravir
- Inhibit viral DNA integration into host genome.
- 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
| Infection | Drug of Choice |
| Pneumocystis pneumonia | Cotrimoxazole (TMP-SMX) |
| Tuberculosis (TB) | Anti-TB regimen + ART (started within 2 weeks) |
| Candidiasis | Fluconazole |
| Toxoplasmosis | Pyrimethamine + Sulfadiazine + Folinic acid |
| CMV Retinitis | Ganciclovir or Valganciclovir |
| Cryptococcal Meningitis | Amphotericin B + Flucytosine, then fluconazole |
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.
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.”