Epidemiology
1% of US population
0.1% of Australia
M:F = 20:1
Groups
- homosexual 80%
- IV User 5%
- heterosexual 8%
- haemophilia 2%
- blood transfusion 1.5 %
Aetiology
Unprotected Sex
Blood
- needle sharing
- blood products
- accidental transmission with infected blood in health care setting
Mother to Child
- pre or post natal
- breast milk
Microbiology
Retrovirus
- reverses RNA of virus into DNA
- incorporates into cell DNA
- uses reverse transcriptase
Pathology
Immune impairment
- destroys CD4 lymphocyte / T Helper cell
Also affects
- B lymphocyte
- monocyte / macrophage cell line
- production of gamma interferon & lymphokines
- bactericidal functions of leukocytes
Wound healing
- via CD4 & lymphokine deficiency
Platelet deficiency
- via Autoimmune Thrombocytic Purpura
Neuropathy
- via Autoimmune Neuritis
Clinical Features
May develop illness at time of acute infection
- seroconversion
- within 2-4 wks of exposure
- lymphadenopathy, myalgia, fever, rash
- viraemia (high transmission risk)
HIV Antibodies appear 3/52 to 4/12 after infection
Proportion will progress to AIDS
- median time of 8-10 yrs
- immune failure
- opportunistic infections
- neoplasms
Stages
1. Early (CD4 > 500)
- average survival 10 yrs
- develop autoimmune disorders
- ITP, Guillaine-Barre, Polymyositis
2. Intermediate (CD4 200-500)
- develop mild infections
- especially skin & mucosa
- Tinea, dermatitis, HSV
3. Late (CD4 < 200)
- average survival 2 years
- severe infections & malignancy
Diagnosis
Window period
- usually 2-6/52
- > 6/12 considered safe
ELISA
- sensitive, but not specific
Western Blot Test
- specific
Complications
Opportunistic Infection
- Pneumocystis Carinii / Mycobacterium Avium complex (lung)
- Toxoplasmosis / Cryptococcal Meningitis (CNS)
Malignant Disease
- Kaposi Sarcoma
- NHL
- 1° CNS Lymphoma
Bacterial Infection
- increased susceptibility
- Pneumonia / CVL phlebitis / Cellulitis / UTI
Musculoskeletal Disease
Polyarthralgia - Self-limiting
Septic Arthritis - Prone to joint sepsis
Reiter's Syndrome
Polymyositis
Myalgia
Surgery
Increased Complication rate
- impaired immune defence
- delayed wound healing
- increased morbidity and mortality from sepsis and wound problems
Rwanda Study
- post Op infection after ORIF
- HIV -ve = 5%
- HIV +ve = 0%
- AIDS = 23%
- CD4 < 250 = 11% Infection
- CD4 > 250 = 1.1% Infection
Preparation for OT
Consider
- immunologist & ID consultation
- Granulocyte-Stimulating Factor / Platelet transfusion
- treat infections
- stop marrow-suppressing AIDS treatments