Immunity and HIV/AIDS

Overview of HIV/AIDS

HIV/AIDS is a major infectious disease that impacts the immune system, leading to immunodeficiency and increased susceptibility to opportunistic infections and certain cancers. Understanding its pathophysiology, risk factors, prevention, and management is essential for personal health and public health awareness.

• HIV (Human Immunodeficiency Virus) is the virus responsible for AIDS (Acquired Immunodeficiency Syndrome).

• First identified in the early 1980s, with significant advances in diagnosis and treatment since then.

• Antiretroviral therapy (ART) has slowed disease progression and improved quality of life.

Pathophysiology of HIV/AIDS

HIV-1 is the primary cause of AIDS, targeting the immune system and specifically infecting cells with the CD4 antigen.

• Transmission: Occurs via sexual contact, sharing needles, and transfusions of infected blood (rare after 1985 due to screening).

• Mechanism: HIV uses reverse transcriptase to convert viral RNA into DNA, which integrates into host cell DNA and replicates during cell division.

• Latency: Virus may remain inactive for years; antibodies are detectable within 6 weeks to 6 months.

• Primary target: Helper T cells (CD4 cells).

Etiology and Epidemiology

HIV/AIDS affects diverse populations, with certain groups at higher risk due to behavioral and demographic factors.

• Men account for over 80% of cases; rapid increases seen among young gay/bisexual men, women, and Black/Hispanic injection drug users.

• Improved perinatal interventions have reduced infection rates in children under 13.

• Early sexual initiation, substance abuse, and lack of awareness contribute to rising cases among adolescents.

Risk Factors

Understanding risk factors is crucial for prevention and health promotion.

• Behavioral: Unprotected sex, sharing drug equipment.

• Medical: Hemophilia, blood transfusions (risk reduced by screening).

• Occupational: Healthcare workers (needlestick injuries, nonintact skin contact).

• No significant racial/ethnic differences among low-income urban populations.

Prevention Strategies

Prevention focuses on education, behavioral change, and medical interventions.

• No vaccine currently available.

• Education: Safe sex practices, awareness of high-risk behaviors, autologous transfusion, informing medical personnel.

• Standard precautions: Treat all patients and high-risk fluids as potentially infectious; use barrier precautions.

• Pre-exposure prophylaxis (PrEP): Daily medication (e.g., Truvada, Descovy) for HIV-negative individuals at risk; >99% effective with other methods.

• Postexposure prophylaxis (PEP): ART started within 72 hours of exposure, continued for 28 days, with follow-up testing.

Clinical Manifestations

Symptoms range from none to severe immunodeficiency, with multiple opportunistic infections and cancers.

• Acute mononucleosis-like illness may occur days to weeks after infection.

• Long asymptomatic period (mean duration: 8–10 years), followed by progression to AIDS (usually 10–15 years after infection).

• CDC and WHO staging systems assess disease severity based on CD4 counts and presence of AIDS-defining conditions.

• AIDS dementia complex: Cognitive, motor, and behavioral impairment.

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

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

Opportunistic Infections

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

• Pneumocystis jiroveci pneumonia: Most common, often fatal.

• Tuberculosis: Rapid progression, diffuse pulmonary infiltrates.

• Candidiasis: Oral thrush, esophagitis, vaginal infections.

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

• Other infections: Herpes, CMV, parasitic, bacterial (salmonella), pelvic inflammatory disease.

Secondary Cancers

HIV/AIDS increases risk for certain cancers.

• Kaposi sarcoma: Most common, indicator of late-stage HIV, may obstruct organs and impair lung function.

• Lymphomas: Non-Hodgkin lymphoma (5x more frequent), primary CNS lymphoma, aggressive and rapidly growing.

• Cervical cancer: Common in women with HIV; aggressive, requires frequent Pap smears and treatment.

Diagnostic Tests

Diagnosis and monitoring involve multiple laboratory tests.

• Screening: Rapid tests, ELISA, combination antigen/antibody tests.

• Confirmatory: HIV-1/HIV-2 differentiation immunoassay, Western blot (no longer preferred), nucleic acid test (NAT), HIV viral load, CD4 count, antiretroviral resistance testing.

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

Pharmacologic Therapy

ART is the cornerstone of HIV/AIDS management, aiming to suppress infection and prevent complications.

• Six drug classes: NRTIs, NNRTIs, PIs, EIs, INSTIs, cytochrome P-450 inhibitors.

• Combination therapy decreases viral load and symptoms but can be complex and expensive.

• Adherence is critical; irregular dosing increases resistance.

• Common drugs: Zidovudine (AZT), nevirapine, efavirenz, enfuvirtide.

• Adverse effects: Metabolic derangements, liver toxicity, Stevens-Johnson syndrome.

• Prevention/treatment of opportunistic infections: Vaccines (pneumococcal, meningococcal, HPV, TDaP, influenza, hepatitis B, Hib), prophylactic isoniazid, treatment for PJP and MAC.

Nonpharmacologic Therapy and Complementary Approaches

Collaboration among healthcare providers and use of complementary therapies can improve comfort and outcomes.

• Limit exposure to infectious diseases, especially in children.

• Some complementary therapies contraindicated (e.g., St. John’s wort with ART).

• Consult healthcare providers before starting CAM therapies.

Lifespan Considerations

HIV/AIDS affects individuals across the lifespan, with unique considerations for each group.

• Pregnant women and newborns: Vertical transmission possible; ART reduces risk; avoid breastfeeding; scheduled cesarean recommended.

• Infants and children: Early identification essential; opportunistic infections and developmental delays common; immunization recommended.

• Adolescents: Risky behaviors, need for autonomy, adherence challenges, misinformation.

• Older adults: May not recognize risks, delayed diagnosis, increased severity, drug interactions.

Nursing Process in HIV/AIDS Care

Nursing care focuses on promoting knowledge, self-care, comfort, and quality of life.

• Assessment: Patient interview, psychosocial assessment, physical examination (vital signs, BMI, nutrition, skin, mental status).

• Diagnosis: Problems include inadequate coping, impaired skin integrity, weight loss, risk for infection, anxiety, compromised sexuality, knowledge deficits.

• Planning: Prevention education, testing, prophylaxis, psychosocial support, direct care needs.

• Implementation: Prevent secondary infections, promote medication adherence, effective coping, skin integrity, nutrition, address sexuality and knowledge deficits.

• Evaluation: Outcomes include freedom from secondary infection, adequate respiratory function, nutrition, coping, school attendance for children/adolescents.

Summary Table: HIV/AIDS Diagnostic Tests

Summary Table: HIV/AIDS Drug Classes

Key Equations and Concepts

• CD4 Count: Used to assess immune function and risk for opportunistic infections.

• Viral Load: Measures the amount of HIV RNA in blood; used to monitor treatment effectiveness.

Example Equation:

Example Application: A patient with a CD4 count of 500 cells/mm3 and a total lymphocyte count of 2000 cells/mm3 has a CD4 percentage of 25%.

Additional info: These notes expand on brief points with academic context, definitions, and examples to ensure completeness and clarity for exam preparation.