HIV

Question 1

Define HIV?

Answer 1

Infection with the human immunodeficiency virus (HIV)

Question 2

what are the methods of HIV transmission?

Answer 2

Question 3

describe the pathophysiology of HIV?

Answer 3

HIV is a Retrovirus (+ sense RNA)

1. HIV enters the CD4 lymphocytes following binding of its envelope glycoprotein (gp120) to CD4 and a chemokine receptor.
2. Reverse transcriptase (in viral core) reads RNA to manufacture DNA
3. Viral DNA is incorporated into the host genome.
4. Dissemination of virions leads to cell death
5. Eventually to T-cell depletion.

Question 4

what are the 3 phases of a HIV invasion?

Answer 4

1. Seroconversion: (4–8 weeks post-infection), self-limiting – fever, night sweats, generalized lymphadenopathy, sore throat, oral ulcers, rash, myalgia, headache, encephalitis, diarrhoea.
2. Early/asymptomatic: (18 months to 15 þyears), apparently well – some patients may have persistent lymphadenopathy (>1 cm nodes, at 2 extrainguinalsites for >3 months). Progressive minor symptoms, e.g. rash, oral thrush, weight loss, malaise.
3. AIDS: Syndrome of secondary diseases reflecting severe immunodeficiency or direct effect of HIV infection (CD4 cell count <200/mm3).

Question 5

describe the presentation of HIV presentation?

Answer 5

Encapsulated organisms (Streptococcus pneumoniae, Haemophilus influenzae)

Bacterial

• Mycobacteria (lungs, GI, skin), staphylococci, Salmonella, capsulated organisms
• *Viral**: CMV, HSV (encephalitis), VZV (recurrent shingles), HPV (warts), papovavirus(progressive multifocal leukoencephalopathy), EBV (oral hairy leukoplakia

Fungal:Pneumocystis pneumonia (PCP), Cryptococcus (meningitis), Candida, invasive aspergillosis.

Protozoal:Toxoplasmosis, cryptosporidiaand microsporidia (diarrhoea).

PA chest x-ray showing severe, bilateral pulmonary interstitial infiltrates with pneumatoceles

Question 6

what is the cause of the presentation of HIV?

Answer 6

due to complications from low levels of CD4+

Question 7

what are the HIV associated tumours?

Answer 7

Kaposi’s sarcoma

• may present as a pink or violaceous (purple) patch on the skin or in the mouth.
• It is an AIDS-defining condition.
• Caused by HHV8

Squamous cell carcinoma (particularly cervical or anal due to HPV)

Lymphoma

Question 8

what are the first line investigations for HIV?

Answer 8

1. ELISA,confirmed with Western blot
2. Serum HIV rapid test
3. Serum HIV DNA PCR - infants
4. CD4 count – indicates immune status, assists staging process
5. Serum viral load (HIV RNA) - millions of copies/mL

Question 9

what are the other tests for HIV?

Answer 9

1. Drug resistance test – to determine therapy
2. Serum hepatitis B and C serology
3. Treponema pallidum haemagglutinationtest – screening for symphilis
4. Tuberculin skin test – TB
5. FBC, U+E, LFTs