HIV

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