Diagnosis

HIV

Etiology

Cause [3xw]

• HIV virus: a blood-borne retrovirus (HIV-1 and HIV-2 subtypes)

• Transmission: sexual intercourse, shared intravenous drug needles, and mother-to-child transmission (birth, breastfeeding)

Pathophysiology [3xw][5iy]

1. Acute HIV infection present with a flulike illness for 2 to 4 weeks --> antibodies against HIV are detected but the immune response is unable to achieve control of the infection

2. The primary viral targets: CD4+ antigen, T cells and macrophages

3. Viral surface glycoproteins facilitates viral entry into the host cell

4. The viral reverse transcriptase enzyme initiates reverse transcription using host transfer RNA as primers --> exponential viral replication

5. Chronic HIV

   • Lymphadenopathy, candidiasis, VZV reactivation, molluscum contagiosum

6. HIV causes depletion of helper T lymphocytes (CD4+ cells) by:

   • Disrupting cell cycling

   • Down-regulating the CD4 molecule

   • Direct cytotoxic effects of viral replication is not the cause of CD4 T-cell loss

7. Loss of CD4+ cells --> Dysregulation of B-cell antibody production

8. AIDS: Severe cellular immune deficiency --> opportunistic infections/malignancies:

   • Bacterial infections: Tuberculosis, mycobacterium avium, pneumonia, salmonella

   • Fungus: Pneumocystis jiroveci, candida, coccidioidomycosis, cryptococcosis, histoplasmosis

   • Parasite: Toxoplasmosis, cryptosporidiosis, isosporiasis

   • Virus: CMV, HSV

   • Immunology: Encephalopathy, Progressive multifocal leukoencephalopathy

   • Cancer: Kaposi sarcoma, lymphoma, cervical cancer (HPV), anal cancer (HPV)

Classification [5iy]

• Category A: Asymptomatic HIV infection

• Category B: HIV infection with symptoms that are directly attributable to HIV infection

• Category C: HIV infection with AIDS-defining opportunistic infections

• These 3 categories are further subdivided on the basis of the CD4+ T-cell count:

  1. > 500/µL: Categories A1, B1, C1

  2. 200-400/µL: Categories A2, B2, C2

  3. < 200/µL: Categories A3, B3, C3

Complications [5iy]

• AIDS: opportunistic infections and HIV-associated malignancies

• Neurocognitive disorders and psychiatric complications

• Polyneuropathy

• Lipodystrophy

• Mitochondrial toxicity

• Kaposi sarcoma

• Inflammatory cytokine syndrome

• Castleman disease

• Lymphoma: follicular, non-Hodgkin, Burkitt, and diffuse large B-cell

• ART-Related Complications

Epidemiology

Incidence per 100.000 [ag4][pfm]

Approach

• HIV-detection: [5iy]

  1. No test can detect HIV during the initial viremic phase (up to 20 days)

  2. PCR: HIV RNA (viral load) 6 to 8 days after infection, up to 33 days

  3. Antigen test: Viral proteins as early as 13 to 20 days after infection

  4. Antigen-antibody tests:

     • Anti-HIV IgM antibodies around 20 days after infection

     • Anti-HIV IgG antibodies around 30 days after infection

  5. Viral culture

  6. Lymph node biopsy

• Blood test: CD4 T-cell count, complete blood count, glucose, blood urea nitrogen, creatinine, liver enzymes, bilirubin, urinalysis, serum lipids, and serology for hepatitis A, B, and C

• Detection of co-infections: tuberculosis, CMV, syphilis, gonorrhea, chlamydia, hepatitis, toxoplasmosis

Treatment

Treatment depends on the stage of the disease and any concomitant opportunistic infections. 

1. Prevention: [3xw]

   • Sexual abstinence

   • Reduction in number of sexual partners

   • Using barrier contraception

   • Treatment of concurrent sexually transmitted diseases (STDs)

   • Testing of self and partner for HIV infection and other STDs

   • Effective control of maternal infection

   • Prenatal antiviral therapy and treatment of mother and infant during labor

   • Cesarean delivery

   • Avoidance of breastfeeding

   • Blood-product and donor screening

   • Avoidance of reusing needles

2. Screening in HIV-patients: diabetes, osteoporosis, colon cancer, cardiovascular risk factors (lipids), trichomoniasis, gonorrhea, chlamydia

3. Prophylaxis: Pneumocystis jiroveci (trimethoprim-sulfamethoxazole), candida or cryptococcus and CMV (fluconazole + ganciclovir if CD4 T-cell counts under 50/µL), Herpes Simplex (acyclovir), Histoplasma capsulatum, Mycobacterium avium complex, Toxoplasma gondii

4. Vaccination: pneumococcal infection, influenza, varicella, hepatitis A and B

5. Treatment: Highly active antiretroviral therapy (HAART) treatment responce:

   • A gradual recovery of CD4 T-cell number

   • Improvement of immune responses

6. Treatment of opportunistic infections

Differential diagnoses

Acne vulgaris, Candidiasis, Contact dermatitis, Cryptococcosis, Cytomegalovirus, Eczema, Folliculitis, Gastroenteritis, Herpes simplex, Herpes zoster, Kaposi sarcoma, Lymphoma, Molluscum contagiosum, Mononucleosis, Oral hairy leukoplakia, Pneumonia, Prurigo nodularis, Psoriasis, Scabies, Seborrheic dermatitis, Severe combined immunodeficiency, Systemic lupus erythematosus, Toxoplasmosis, Tuberculosis, Verruca vulgaris, Viral hepatitis