HIV Flashcards
What is HIV?
Single stranded RNA retrovirus which infects and replicates in human lymphocytes (CD4+ T-cells), macrophages and dendritic cells.
What is AIDS?
Progressive immune system dysfunction, opportunistic infection and malignancy.
How is HIV transmitted?
Via blood, sexual fluids, and breast milk.
What is the pathophysiology of HIV infection?
- HIV binds via gp120 glycoprotein to CD4+ receptors on Th cells, macrophages and dendritic cells.
- Viral RNA reverse transcribed to DNA and integrated integrated into host cells.
- Cells migrate to lymph tissue where virus replicates producing billions of new virions.
What are the risk factors for HIV infection?
IVDU, unprotected reciprocal anal intercourse, unprotected reciprocal penile-vaginal intercourse, vertical transmission (high viral load), blood transfusion/transplant, occupational.
How is HIV infection prevented?
- Barrier contraception
- PEP - anti-retroviral therapy, up to 72h after exposure, test 8-12 weeks after exposure.
- PrEP - ART in those at high risk of acquiring HIV
- ART in pregnancy women by 24/40, Caesarean if viral load >50 copies/ml, neonatal PEP
What is the presentation of HIV?
- Early - seroconversion illness, acute retroviral syndrome (2-4 weeks after infection)
- Latent - tends to be asymptomatic
How is suspected HIV investigated?
- 1st line - 4th gen ELISA for HIV Ab and Ag (test at 4 weeks)
- Rapid point of care testing
- Viral load - monitor response to ART
- Nucleic acid testing - quantitative test for presence of viral RNA
- CD4+ count - monitor immune system function and disease progression (<200 defining criteria for AIDS)
What is the treatment for HIV and what are some side effects?
- Highly active anti-retroviral therapy (start immediately)
2. N&V, bone marrow suppression, dyslipidaemia
What are the options for HAART?
Typically backbone 2 nucleoside reverse transcriptase inhibitors plus one of:
- Non-nucleoside reverse transcriptionase inhibitor - stop conversion of RNA to DNA
- Integrase inhibitor - prevent integration into host DNA
- Protease inhibitor - prevents virus maturation
- CCR5 antagonist - prevent viral entry into cell
What are the complications of HIV infection?
- Pneumocystis jirovecii
- Candidiasis
- Cryptococcus neoformans
- Toxoplasma gondii
- CMV
- Cryptosporidium
- Kaposi’s sarcoma - AIDS defining (HSV-8)
- Non-Hodgkin’s lymphoma
What is the criteria for an AIDS diagnosis?
- <200 T-cells/mm^3
- Persistent fever
- Weight loss
- Fatigue
- Diarrhoea
- HIV in blood increases significantly
What are the AIDS defining conditions?
- Recurrent bacterial pneumonia
- Pneumocystis pneumonia
- Fungal infections
- Kaposi’s sarcoma
- Primary lymphoma
What are the appropriate steps in counselling for a HIV patient?
- Pre-test consent - reasons for test, risk assess, beliefs and understanding of HIV, info about test, implications of +ve result.
- Post-test - if -ve, safe sex, re-testing may be needed; if +ve, allow expression of emotions, talk about fears, crisis intervention/suicide risk assessment, follow-ups, support group and charities.
