Human Immunodeficiency Virus

Question 1

Classification

Answer 1

Virus
RNA
Positive-stranded
Retrovirus
HIV

Question 2

Presentation
CD4 < 400 cells/ uL blood

Answer 2

Constitutional symptoms (“wasting syndrome”)
Weight loss
Fever
Night sweats
Adenopathy

Bacterial infections
M. tuberculosis
H. influenzae
S. pneumoniae
Salmonella
Nocardia may cause TB-like pulmonary cavitations

Oral thrush (Candida albicans)
Tinea pedis
Reactivation VZV

Question 3

Presentation
CD4 < 200cells/μL blood

Answer 3

PCP (Pnuemocystis jiroveci pneumonia)
Cryptococcus neoformans
Cryptosporidium
Coccidioidomycosis
Reactivation HSV
Iospora

Question 4

Presentation
CD4 < 100cells/μL blood

Answer 4

Toxoplasma gondii
Histoplasmosis
Candida albicans esophagitis; Candida is the most common cause of esophagitis in late HIV

Question 5

Presentation
CD4 < 50cells/μL blood

Answer 5

M. avium-intracellulare
CMV; retinitis and esophagitis
Cryptococcus neoformans; meningoencephalitis

Question 6

Presentation
HIV in the neonate (a ToRCHeS infection)

Answer 6

Recurrent infections
Oral thrush
Interstitial pneumonia
Chronic diarrhea
Lymphopenia

Question 7

Presentation
HIV encephalitis

Answer 7

HIV crosses BBB via infected macrophages
Results in inflammation in the brain appearance of microglial nodules with multinucleated giant cells
Occurs late in the course of HIV infection

Question 9

Presentation
AIDS dementia complex

Answer 9

Mental status changes
Depression
Ataxia
Seizures
Urinary and bowel incontinence

Question 9

Evaluation
Diagnosis of HIV

Answer 9

ELISA is the first step in diagnosis
High false-positive rate (high sensitivity, low specificity)
Rules OUT the possibility of infection

Western blot is then used to confirm positive results
High false-negative rate (low sensitivity, high specificity)
Rules IN the diagnosis of infection

Both tests detect antibodies to HIV proteins
Antibodies take 3-6 weeks to develop
Tests can be falsely negative in first 1-2 months of infection
Tests can be falsely positive in babies born to infected mothers
Anti-gp120 crosses placenrta

The presence of viral RNA or antigens (e.g. p24) can also be tested directly

Question 10

Evaluation
Diagnosis of AIDS

Answer 10

≤ 200 CD4+ (normal: 500-1500)
HIV positive with AIDS-associated infection; e.g. P. jiroveci pneumonia

Viral load tests
PCR used to monitor effects of therapy on viral load

Question 11

Treatment

Answer 11

Over 25 HIV drugs exist in multiple categories
CCR5 inhibitors
Fusion inhibitors
Reverse transcriptase inhibitors
Integrase inhibitors
Protease inhibitors

Highly active antiretroviral therapy (HAART)
Combines multiple drugs with multiple mechanisms of action to prevent resistance
e.g. tenofovir + emtricitabine + efavirenz or many other possible
combinations

Pregnancy
Use zidovudine (ZDV, AZT) to prevent mother-to-fetus transmission
Efavirenz and delavirdine are thought to be teratogenic
HIV is an absolute contraindication to breastfeeding in the United States

Vaccination against secondary infection
Pneumoccal vaccine is indicated in HIV-positive patients
Live vaccines are contraindicated in HIV-positive patients