Human Immunodeficiency Virus (HIV)

What is HIV

• RNA retrovirus that causes progressive immune system damage

• HIV trgets CD4+ T-helper lymphocytes

• progressive loss of immune function occurs

• infection is chronic but treatable with ART

• without treatment, HIV progresses into AIDS

• HIV and AIDS are not the same diagnosis

• AIDS criteria:

  • CD4 count <200 cells

  • or presence of an AIDS-defining illness

How is HIV transmitted

• exposure to infected:

  • blood

  • semen

  • vaginal secretions

  • breast milk

What are major transmission routes

• unprotected sexual contact

• injection drug use

• perinatal transmission

• occupational exposure

What is the risk of HIV transmission from a needle stick injury

~0.3%

• increased with:

  • blood of pt with high level of circulating HIV

  • deep puncture wound

  • need with hollow bore and visible blood

How is HIV NOT transmitted

• saliva

• tears

• sweat

• causal contact

• respiratory droplets

Perinatal Transmission

• can occur during pregnancy, delivery, or breastfeeding

• on average, 25% of infants born to women with untreated HIV will be born with the infection

• Treatment with ART can reduce rate of transmission to less than 1%

Acute Infection

• usually occurs 2-4 weeks after exposure

• common symptoms resemble the flu

  • fever

  • fatigue

  • rash

  • lymphadenopathy

  • sore throat

• very high viral load

• highly infectious stage

• many patients do not recognize symptoms

Who is HIV screening recommended for?

• all adults age 15-65 at least once

• individuals with high-risk behaviors

• patients with STI

What are common diagnostic tests?

• HIV antigen/antibody assay

  • antibodies typically detectable within 2-3 weeks

• ELISA screening test

• confirmatory RNA testing

CD4 Count

• measures immune system strength

• normal: 800-1200 cells

• <500 indicates immune dysfunction

• <200 indicates AIDS

• CD4 reflects immune status

Viral Load

• measures HIV RNA in the blood

• indicates viral activity

• used to evaluate treatment effectiveness

• Treatment goal = undetectable viral load

• viral load reflects viral activity

CD4 >500

• immune function usually preserved

• many patients remain asymptomatic

CD4 200-500

• increased risk for infections

• early symptoms may develop

CD4 <200

• severe autoimmune suppression occurs

• AIDS diagnosis is made

• Opportunistic infections become likely

Stage 1

• Acute HIV infection

  • flu-like symptoms

  • high viral load

  • highly infectious

Stage 2

• Chronic HIV infection

  • often asymptomatic

  • gradual decline in CD4 count

  • approximately period of 10 years from initial infection

Stage 3

• AIDS

  • diagnosis requires: CD4 <200 cells OR an AIDS-defining illness

Opportunistic infections and cancers

• candida infections

• penumocystis jirovecii pneumonia

  • Resp symptoms with CD4 <200

• Toxoplasmosis

• Tuberculosis

• Cytomegalovirus

• Non-Hodgkin lymphoma

• Kaposi sarcoma

  • purple or brown skin lesions

  • may appear on skin or oral mucosa

HIV Wasting Syndrome

• complication of advanced HIV

• defined as:

  • >=10% unintentional body weight loss

  • chronic diarrhea

  • severe weakness

  • loss of lean body mass

• contributes significantly to morbidity in advanced disease

Antiretroviral Therapy (ART)

• standard treatment for HIV infection

• combination therapy - never just one prescribed

• medications from different drug classes

  • Nucleoside Reverse Transcriptase Inhibitors

  • Non-nucleoside Reverse Transcriptase Inhibitors

  • Protease Inhibitors

  • Intergrase Inhibitors

Goals of treatment with ART

• suppress viral replication

• increase CD4 count

• prevent opportunistic infections reduce transmission risk

What can poor adherence lead to ?

• drug resistance

• treatment failure

• increased viral load

• disease progression

• the most common cause of ART failure is poor adherence

Strategies to improve adherence

• simplified medication regimens

• pill organizers

• reminder systems

• integration into daily routines

Key HIV prevention strategies

• safer sexual practices

• routine HIV testing

• treatment of HIV-positive individuals

• Pre-exposure prophylaxis (PrEP) medication taken before exposure reduces risk of HIV infection by >90%

Post-workplace HIV exposure

• Immediately wash the exposure site

• report the incident

• start post-exposure prophylaxis (PEP)

  • typically 28 days of treatment