Human immunodeficiency virus (HIV) Flashcards
1
Q
Define
A
DEFINITION: infection with the human immunodeficiency virus (HIV)
2
Q
Causes
A
HIV is transmitted by:
Sexual intercourse
- Heterosexual intercourse is the MOST COMMON mode of transmission
- Homosexuals are at greater risk in the West
Blood (and other bodily fluids)
- Mother to child (intrauterine, childbirth, breastfeeding)
- Needles
- Blood transfusions
Pathophysiology
HIV enters CD4+ lymphocytes by binding to their gp120 receptors
Reverse transcriptase allows the incorporation of HIV genetic material into the host genome
This leads to dissemination of HIV, cell death and eventual T-cell depletion
- Organ transplantation
3
Q
Epidemiology
A
Increasing in incidence in Africa and Asia
4
Q
Symptoms and signs
A
There are THREE phases of HIV:
Seroconversion
- Self-limiting
- Fever
- Night sweats
- Generalised lymphadenopathy
- Sore throat
- Others: oral ulcers, rash, myalgia, headache, encephalitis, diarrhoea
Early/Asymptomatic
- Apparently well
- Some may have persistent lymphadenopathy
- Progressive minor symptoms (e.g. rash, oral thrush, weight loss)
AIDS
- Syndrome of secondary diseases resulting from immunodeficiency
Direct Effects of HIV Infection
- Neurological: polyneuropathy, dementia
- Lung: lymphocytic interstitial pneumonitis
- Heart: cardiomyopathy, myocarditis
- Haematological: anaemia, thrombocytopaenia
- GI: anorexia, wasting
- Eyes: cotton wool spots
Secondary effects resulting from immunodeficiency
- Bacterial Infection: TB, skin infections, pneumococcal infections
- Viral: CMV, HSV, VZV, HPV, EBV
- Fungal: pneumocystic jirovecii pneumonia, Cryptococcus, candidiasis, invasive aspergillosis
- Protozoal: toxoplasmosis, cryptosporidia
- Tumours: Kaposi sarcoma, SCC, non-Hogkin’s lymphoma, Hodgkin’s lymphoma
5
Q
Investigations
A
HIV testing - HIV antibodies, PCR for viral RNA, CD4 count, viral load
Others
- Pneumocystic pneumonia - CXR
- Cryptococcal meningitis - brain CT or MRI, LP
- CMV (colitis) - colonoscopy and biopsy
- Toxoplasmosis - brain CT or MRI
- Cryptosporidia - stool microscopy
