HIV Infection: Etiology and Epidemiology

HIV Infection

• Global situation and trends:
  • Over 70 million people infected with HIV virus
  • About 35 million people died of AIDS
  • 37 million people living with HIV at the end of 2015
  • Male > female (70%)
  • African American & Hispanics affected more
• Use of antiretroviral drugs:
  • Slowed progression of HIV to AIDS and prolonged life span
  • Changed from fatal disease to chronic illness in industrialized countries
  • People living to old age and children living into adulthood

HIV Transmission

• Risk factors:
  • Sexual practices (unprotected sex, multiple sexual partners, anal or oral sexual activity)
  • Improper condom use
  • Open sores, lesions, or irritation in genital area
  • Body fluids, blood, urine, semen
  • IV drug users
  • Women infected - transmitted thru gestation, delivery, breast milk (rare)
• Not transmitted by:
  • Casual contact
  • Sneezing, cough, toilet seats, bathtub, swimming pools, dishes, utensils, linens of infected person
  • Biting or blood sucking insects
  • Blood transfusions (not significant source of infection; HIV screening done since 1985)

Primary Infection

• Manifestations:
  • Dramatic burst of HIV activity with high viral load and decrease in CD4 count
  • 50%-70% of persons have symptoms of flu-like syndrome, but do not relate to HIV
  • Diagnosis often missed by primary care provider
• CDC recommends HIV testing for all patients between ages 13 to 64 in all health care settings (no separate consent required)

AIDS

• HIV is an acquired infection that:
  • Integrates itself into CD4 (T4) helper cells
  • Causes severe immune dysfunction, rendering the infected person susceptible to life-threatening infections and malignancies
  • Results in acquired immunodeficiency syndrome (AIDS)
  • Remains incurable

Diagnostic Tests

• ELISA blood test: sensitive for HIV 1 antibodies
• Western Blot: confirmation test for HIV
• CD4 counts and HIV viral loads can be used to diagnose AIDS and evaluate treatment

Stages of HIV

Secondary Stage

• May last 10 years; course of illness varies from person to person
• Pt. free from major symptoms; as viral load increases, CD4 cell count declines
• Virus in lymph; viral load test done; high viral load and low CD4 count do not correlate with physical signs
• AIDS exists when CD4 cell count drops below 200 per microliter of blood and opportunistic infections occur

Stage 3: Symptomatic HIV Infection

• HIV crosses blood-brain barrier and causes encephalopathy
• Opportunistic infections affect:
  • Respiratory system (Pneumocystis Carinii pneumonia, TB, Kaposi's sarcoma)
  • GI system (Candida, CMV or cytomegalovirus, cryptosporidiosis)
  • CNS (toxoplasmosis, cryptococcosis, varicella zoster, herpes simplex)

Stage 4: HIV

• HIV wasting syndrome: weight loss of 10-15%
• Other opportunistic infections occur
• Pneumocystic carinii pneumonia: prophylaxis should start when CD4 count is less than 200 to 300 cells/mm3
• Toxoplasmosis of brain
• Candidiasis esophagus, trachea, bronchi
• Herpes simplex virus infection
• Extra pulmonary TB
• Lymphoma
• HIV encephalopathy and dementia, blindness, death

Opportunistic Infections

• Cause clinical manifestations of HIV
• Symptoms: chills, fever, night sweats, dry productive cough, dyspnea, confusion, seizures, headache, malaise, fatigue, oral lesions, skin rash, abdominal discomfort, diarrhea, weight loss, lymphadenopathy, progressive generalized edema

Immunologic Manifestations of AIDS

• CD4 count: used to measure extent of immune damage that has occurred as a result of infection and complications
• Used to monitor antiretroviral therapy
• Used in conjunction with viral load to predict possibility of viral progression, determine when to start therapy, and monitor effectiveness of treatment

HAART (Highly Active Antiretroviral Therapy)

• Protease inhibitors combined with 2 other drugs (reverse transcriptase inhibitors and non-reverse transcriptase inhibitors), forming a "cocktail"
• Decrease viral load by disrupting HIV at different stages of replication
• Serious side effects: require oversight by primary care provider and high level of compliance

HIV and Opportunistic Infections

• Occur with a variety of organisms due to profound immunosuppression of person with AIDS
• Opportunistic infections may result from primary infections or reactivation of latent infection
• May have more than 1 infection at one time
• HAART therapy is the most effective way to prevent opportunistic infections associated with HIV

Focus:

• Risks
• Signs and symptoms
• Patient teaching

This quiz covers the global situation and trends of HIV infection, including the number of people affected, demographics, and the impact of antiretroviral drugs on the progression of the disease.