HIV/AIDS: Immunity, Pathophysiology, Clinical Manifestations, and Nursing Care

Immunity: HIV/AIDS

Overview of HIV/AIDS

Human Immunodeficiency Virus (HIV) and Acquired Immunodeficiency Syndrome (AIDS) are diseases that compromise the immune system, primarily by targeting CD4 (helper T) cells. The loss of these cells impairs the body's ability to fight infections and certain cancers. Antiretroviral therapy (ART) has slowed disease progression, but HIV remains a major public health concern.

• HIV: A virus that infects CD4 cells, weakening immune defenses.

• AIDS: The advanced stage of HIV infection, characterized by severe immunodeficiency and opportunistic diseases.

• CD4 cell count: Used to predict disease severity and progression.

• Antiretroviral therapy (ART): Medications that slow HIV progression and reduce transmission risk.

Pathophysiology of HIV/AIDS

HIV-1 is the primary cause of AIDS. The virus is present in body fluids and infects CD4 antigen-bearing cells. A key step in HIV replication is the use of reverse transcriptase to convert viral RNA into DNA, which integrates into the host genome and may remain dormant for years.

• Reverse transcriptase: Enzyme converting viral RNA to DNA.

• Integration: Viral DNA becomes part of host cell DNA.

• Seroconversion: Antibodies to HIV become detectable within 6 weeks to 6 months after infection.

Etiology of HIV/AIDS

HIV/AIDS affects diverse populations, with notable increases among women, Black and Hispanic ethnicities, young gay/bisexual men, and injection drug users. Improved perinatal interventions have reduced infection rates in children under 13 years.

• Primary affected groups: Men (80% of cases), increasing rates in women and minorities.

• Contributing factors: Early sexual initiation, substance abuse, lack of risk awareness.

• Older adults: Increasing cases in patients aged 50 and older.

Risk Factors and Prevention

HIV is transmitted through sexual contact, infected blood, and historically through transfusions. Prevention focuses on education, safe practices, and medical interventions.

• Transmission routes: Sexual contact, needle sharing, blood transfusions (pre-1985).

• Behavioral risk factors: Unprotected sex, sharing drug equipment.

• Prevention strategies:

  • Education on safe sex and drug use.

  • Barrier precautions and standard precautions for healthcare workers.

  • Pre-exposure prophylaxis (PrEP): Daily medication (e.g., Truvada, Descovy) for high-risk individuals.

  • Post-exposure prophylaxis (PEP): ART within 72 hours of exposure, continued for 28 days.

Clinical Manifestations

Symptoms range from asymptomatic to severe immunodeficiency, opportunistic infections, and cancers. The disease often begins with an acute illness, followed by a long asymptomatic period.

• Acute phase: Mononucleosis-like illness days to weeks after infection.

• Asymptomatic period: Lasts 8-10 years on average.

• Progression to AIDS: Occurs 10-15 years after infection, marked by opportunistic infections and cancers.

Classification Systems

HIV/AIDS is classified by the CDC and WHO based on CD4 counts and presence of AIDS-defining conditions.

• CDC system: Uses CD4 cell counts and HIV-related conditions.

• WHO system: Used when CD4 counts are unavailable; defines four stages based on T-lymphocyte count and clinical conditions.

Neurological Manifestations

HIV/AIDS can affect both the central and peripheral nervous systems, leading to cognitive, motor, and behavioral changes.

• AIDS dementia complex: Memory loss, confusion, lethargy, motor disturbances.

• CNS manifestations: Toxoplasmosis, non-Hodgkin lymphoma, cryptococcal meningitis, cytomegalovirus.

• PNS manifestations: Numbness, tingling, pain, weakness, paralysis.

Opportunistic Infections

Opportunistic infections are common in AIDS, often predictable by CD4 count.

• Pneumocystis jiroveci pneumonia (PJP): Most common, frequent cause of death.

• Tuberculosis: Rapid progression, disseminated disease.

• Candidiasis: Oral thrush, esophagitis, vaginal infections.

• Mycobacterium avium complex (MAC): Late-stage, associated with wasting syndrome.

• Other infections: Herpes, CMV, salmonella, pelvic inflammatory disease.

Secondary Cancers

HIV/AIDS increases risk for certain cancers, especially Kaposi sarcoma, lymphomas, and cervical cancer.

• Kaposi sarcoma (KS): Most common, indicator of late-stage HIV; linked to herpes virus.

• Lymphomas: Non-Hodgkin lymphoma, primary CNS lymphoma, aggressive growth.

• Cervical cancer: Common in HIV-infected women; regular Pap smears and aggressive treatment are essential.

Diagnostic Tests and Therapies

Diagnosis and management involve screening, confirmatory, and monitoring tests, as well as collaborative care.

• Screening tests: Rapid tests for HIV antibodies.

• Confirmatory tests:

  • ELISA (antibody test)

  • Combination antigen/antibody tests

  • HIV-1/HIV-2 differentiation immunoassay

  • Nucleic acid test (NAT)

• Monitoring tests: HIV viral load, CD4 cell count, antiretroviral resistance testing.

• Other tests: CBC, tuberculin skin test, MRI, cultures, Pap smears.

Pharmacologic Therapy (ART)

ART aims to suppress HIV, prevent opportunistic infections, and treat complications. Combination therapy is standard, with six classes of antiretroviral drugs.

• Nucleoside Reverse Transcriptase Inhibitors (NRTIs): Inhibit reverse transcriptase (e.g., Zidovudine).

• Nonnucleoside Reverse Transcriptase Inhibitors (NNRTIs): Cross-resistance, liver toxicity (e.g., Nevirapine, Efavirenz).

• Protease Inhibitors (PIs): Inhibit viral protease, cause metabolic derangements.

• Entry Inhibitors (EIs): Prevent viral entry (e.g., Enfuvirtide).

• Integrase Strand Transfer Inhibitors (INSTIs): Block viral DNA integration.

• Cytochrome P-450 Inhibitors: Enhance effectiveness of other drugs.

Vaccinations and prophylactic treatments are critical for preventing opportunistic infections and malignancies.

Nonpharmacologic Therapy

Collaboration among healthcare providers is essential. Complementary and alternative therapies (CAM) may help with side effects, but some (e.g., St. John's wort) are contraindicated with ART.

• CAM: Consult physician before use; some may interact with ART.

• Care coordination: Involvement of childcare, school, and camp personnel for children.

Lifespan Considerations

Pregnant Women and Newborns

Vertical transmission can occur during pregnancy or delivery. ART reduces transmission risk, and breastfeeding should be avoided.

• Prophylactic ART: Reduces newborn infection risk from 25-30% to below 5%.

• Cesarean delivery: Recommended at 38 weeks to reduce risk.

• Early identification: Prophylactic AZT and PJP prophylaxis for infants.

Infants and Children

Infants may be asymptomatic at birth but develop infections and symptoms within months. Early diagnosis and immunization are crucial.

• Symptoms: Enlarged spleen/liver, recurrent infections, weight loss, oral candidiasis.

• Diagnosis: HIV DNA PCR and RNA assays preferred; ELISA and Western blot not used before 18 months.

• Immunization: Recommended as soon as age-appropriate.

Adolescents

Adolescents are at high risk due to sexual behaviors and may face challenges with adherence and psychosocial support.

• Risk factors: Risky sexual behavior, lack of support, misinformation.

• Challenges: Adherence, autonomy, peer pressure, denial.

Older Adults

Older adults may not recognize HIV risks, and diagnosis is often delayed due to attribution to aging or other diseases.

• Drug interactions: Increased risk with ART.

• Delayed diagnosis: Symptoms may be masked by other conditions.

Nursing Process in HIV/AIDS Care

Nursing care focuses on promoting knowledge, self-care, comfort, and quality of life. Culturally competent care is essential as HIV becomes a secondary diagnosis for many patients.

• Assessment: Observation, interview, psychosocial assessment, physical examination.

• Diagnosis: Coping skills, skin integrity, weight loss, infection risk, anxiety, sexual activity, knowledge deficits.

• Planning: Education, testing, prophylaxis, follow-up, evolving care needs.

• Implementation:

  • Prevent secondary infections: Immunization, hygiene, exposure limitation.

  • Promote medication adherence: Education, behavior modification, tailored regimens.

  • Promote coping: Support networks, emotional support, consistent care.

  • Maintain skin integrity: Monitor, prevent breakdown, use dressings, encourage movement.

  • Promote nutrition: Assess status, provide high-protein diet, manage symptoms.

  • Address sexuality: Factual information, safer sex practices, emotional support.

  • Address knowledge deficits: Education on all aspects of care and prevention.

• Evaluation: Outcomes include infection prevention, adequate nutrition, coping, and support for children/adolescents.

Table: Classes of Antiretroviral Drugs

Class	Mechanism	Example(s)	Key Side Effects
NRTIs	Inhibit reverse transcriptase	Zidovudine (AZT)	Anemia, neutropenia
NNRTIs	Non-competitive inhibition of reverse transcriptase	Nevirapine, Efavirenz	Liver toxicity, rash
Protease Inhibitors	Inhibit viral protease	Ritonavir, Indinavir	Metabolic derangements
Entry Inhibitors	Prevent viral entry	Enfuvirtide	Injection site reactions
INSTIs	Block viral DNA integration	Raltegravir	Headache, insomnia
Cytochrome P-450 Inhibitors	Enhance drug effectiveness	Cobicistat	Drug interactions

Key Formula: CD4 Cell Count

The CD4 cell count is a critical measure for monitoring HIV progression:

$\text{CD4 Cell Count} = \frac{\text{Number of CD4 cells}}{\text{mm}^3 \text{ of blood}}$

Normal range: 500-1,500 cells/mm3. AIDS is diagnosed when CD4 count falls below 200 cells/mm3.

Example: Prevention with PrEP

A 25-year-old man at high risk for HIV infection takes daily Truvada (PrEP) and practices safe sex. His risk of acquiring HIV is reduced by over 99% compared to unprotected exposure.

Additional info: Academic context was added to clarify mechanisms, drug classes, and diagnostic strategies, as well as to provide a self-contained summary suitable for exam preparation.