- Acquired immunodeficiency syndrome (AIDS) was first recognised in the USA in the 1970s
- Human immunodeficiency virus (HIV) was isolated in 1983
- In 1984 a serological test for antibodies to the virus became available
- In 1996 WHO estimated worldwide that there were:
- 3.1 million new cases of HIV infections
- 29 million people were infected with HIV
- In UK to date 58,000 have been HIV positive and 18,000 have developed AIDS
- 30-50% of of HIV positive patients are unaware of their infection
- HIV is a treatable disease
- Where therapy is available infected individuals have the same rate of death as aged-matched uninfected
controls
Immunology
- HIV is a double-stranded RNA retrovirus
- Attaches to human immune cells through the CD4 molecule
- It produces DNA by the use of the enzyme reverse transcriptase
- DNA is the incorporated into host cells
- The incorporated viral DNA produces new viral components which are spliced and assembled using a viral
protease
- HIV infection results in widespread immunological dysfunction
- It results in a fall in CD4 lymphocytes, monocytes and antigen-presenting cells
- Immunological dysfunction results in opportunistic infections and increases risk of malignancy
- The virus is transmitted in bodily fluids by
- Heterosexual intercourse - Africa and Asia
- Homosexual intercourse - UK and North America
- Blood transfusions
- Intravenous drug abuse
- Perinatal transmission
Natural history
- Up to three months there is often an asymptomatic viraemia
- Patients are infective during this period
- ELISA test for HIV antibodies are negative
- At seroconversion an acute seroconversion illness (ASI) can occur
- May be followed by persistent generalised lymphadenopathy (PGI)
-
Progression to symptomatic disease occurs within several years
-
AIDS develops within 5 to 10 years
-
AIDS diagnosed by the presence of an AIDS indicator disease with
a positive HIV test
-
Median survival with AIDS is 2 years
-
5% of HIV positive patients have remained well without therapy
for more than 20 years
Serological changes with disease progression
AIDS indicator diseases
- Multiple recurrent bacterial infections
- Tracheal or bronchial candidiasis
- Invasive cervical carcinoma
- Extrapulmonary or disseminated coccidiodomycosis
- Cryptosporidiosis
- Cytomegalovirus retinitis
- HIV encephalopathy
- Disseminated or extrapulmonary histoplasmosis
- Kaposi's sarcoma
- Lymphoma
- Disseminated mycobacteriosis
- Pneumocystis carinii pneumonia
- Progressive multifocal leukoencephalopathy
- Cerebral toxoplasmosis
Sites of pyogenic infections in AIDS
- Thoracic empyema
- Anorectal abscesses
- Skin boils, carbuncles and cellulitis
- Necrotising fasciitis
- Pyomyositis
- Osteomyelitis
- Septic arthritis
- Epididymo-orchitis
- Pelvic inflammatory disease
- Appendicitis
Treatment
- HIV therapies are available that:
- Prevent virus entry into cells
- Inhibit viral reverse transcriptase
- Inhibit viral protease
- Combination therapy with anti-HIV drugs:
- Inhibits viral replication
- Reduces viraemia to undetectable levels
- Leads to reconstitution of immune dysfunction
- Prevents opportunistic disease
- Stopping therapy leads to re-emergence of viraemia
Bibliography
Jaffray C E, Flint L M. Blood-borne viral diseases and the surgeon. Curr Probl Surg
2003; 40: 195-251. |