AIDS (Acquired Immune Deficiency Syndrome) is a chronic and life-threatening condition caused by the Human Immunodeficiency Virus (HIV). The virus attacks and gradually destroys the immune system, making the body unable to fight common infections and cancers. HIV spreads mainly through unprotected sexual contact, infected blood, and from mother to child during pregnancy, delivery or breastfeeding. There is no permanent cure, but antiretroviral therapy (ART) can greatly slow the disease and reduce complications.
Symptoms of HIV & AIDS
1. Primary (Acute) HIV Infection
Occurs 2–6 weeks after exposure. Many patients develop a flu-like illness lasting 1–2 weeks. Symptoms include:
- Fever
- Rash
- Headache
- Sore throat and mouth ulcers
- Muscle and joint pains
- Swollen lymph nodes
This stage has a very high viral load, making the infection highly contagious.
2. Clinical Latent (Chronic) Infection
HIV remains active in the body but multiplies slowly. There may be persistent lymph node swelling. This stage may last 10 years without treatment, and even longer with ART. Some people progress faster.
3. Symptomatic HIV Infection
As CD4 cells decline, patients develop infections and symptoms such as:
- Fever
- Fatigue
- Weight loss
- Chronic diarrhea
- Oral thrush
- Shingles (herpes zoster)
4. Progression to AIDS
When the immune system becomes severely damaged, opportunistic infections and cancers appear. Symptoms include:
- Night sweats
- Severe, persistent diarrhea
- Recurring fever
- Unexplained fatigue
- Oral white patches
- Severe weight loss
- Skin rashes or nodules
Pathogenesis
HIV destroys the immune system mainly by targeting CD4+ T cells, which coordinate immune responses.
- After entry, HIV multiplies rapidly and produces millions of viral particles.
- There is a sudden drop in CD4+ T cell count during acute infection.
- CD8+ cytotoxic T cells initially control the viral load but cannot eliminate the virus.
- The virus continues to replicate inside lymphoid tissues, slowly damaging the immune system.
- Most CD4+ T cells are lost early in the intestinal mucosa due to high CCR5 receptor expression.
- During chronic infection, continuous immune activation and reduced new T-cell production lead to gradual CD4 decline.
- AIDS develops once CD4 count drops below a critical level and opportunistic infections appear.
Causes and Transmission of HIV
1. Unprotected Sexual Contact
HIV spreads through vaginal, anal or oral sex when infected blood, semen or vaginal fluids enter micro-tears in mucosal surfaces.
2. Blood Transfusion
Transmission through infected blood is now rare due to strict screening.
3. Sharing Needles
Using contaminated needles (drug use, tattooing, piercing) increases risk.
4. Mother-to-Child Transmission
Occurs during pregnancy, childbirth or breastfeeding. ART significantly reduces this risk.
Complications of HIV/AIDS
As immunity weakens, patients develop multiple infections and cancers.
A. Opportunistic Infections
Tuberculosis (TB)
The most common opportunistic infection worldwide and a major cause of death in HIV patients.
Cytomegalovirus (CMV)
Causes serious disease when immunity is weak, affecting eyes, lungs and digestive tract.
Candidiasis
Fungal infection of mouth, throat or vagina causing white patches and inflammation.
Cryptococcal Meningitis
Fungal infection of the brain covering; presents with fever, headache and neck stiffness.
Other infections include toxoplasmosis and cryptosporidiosis.
B. Cancers
Kaposi’s Sarcoma
Vascular tumor causing red-purple skin lesions; common in advanced AIDS.
Lymphoma
Cancer of lymphocytes; presents with painless swelling of lymph nodes.
C. Other Complications
Wasting Syndrome
Loss of more than 10% body weight with diarrhea, fever and weakness.
Neurological Problems
Includes depression, confusion, memory loss and AIDS dementia complex.
Kidney Disease
HIV-associated nephropathy (HIVAN) is common in late stages.
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