AIDS and HIV     

This disease is unusual in that it is a transmissible form of immunodeficiency and many hundreds of thousands of cases have now been reported worldwide. Many millions of people are now infected, particularly in Africa and the developing world.

 

AIDS can be defined as the presence of HIV virus and one of 25 specific severe opportunistic infections. This constellation of opportunistic infections, particularly by Pneumocystis carinii and / or Kaposi’s sarcoma or other tumours, are associated with severe immunodefiency in a previously healthy person.

 

HIV specifically attacks T-helper lymphocytes (CD4 cells) and cases progressive immunodeficiency. Virtually all persons who are HIV antibody– positive will develop AIDS. Absence of HIV antibody does not exclude infection with HIV.

 

The incubation period of AIDS is highly variable, but can be as long as 10—15 years. This is mainly because depression of the immune system may take a considerable time to become clinically apparent as opportunistic infection.

 

In addition to its effects on the immune system, the AIDS virus also attacks the brain, and patients can develop increasing encephalopathy and ultimately  dementia sometimes in the absence of significant immunodeficiency.

 

HIV antibody testing can be done 3 months from time of infection. A negative result means antibodies to HIV have not been found in the blood. However, some patients are infected with HIV but do not appear to produce antibody to it. Indiscriminate screening is discouraged and any potential advantages should be weighed carefully against potential psychological sequelae to patients on learning that they have a potentially life-threatening infection which they can transmit to others. In the UK, patients must be counselled before being tested.

            

Needlestick injuries

HIV risk of seroconversion 0.3%, 0.1ml of blood required

Hep B risk of seroconversion 7—30%, 0.00004mls of blood required

 

CD4 count and disease progression            

CD4 count in cells per mm cubed

¨ >600 Normal

¨ 400– 600 Initial immune suppression

¨ <200 Severe opportunistic infection 

¨ <50  Poor prognosis of survival <1 year

 

Opportunistic infections associated with HIV

¨ Recurrent genital herpes   

¨ Herpes Zoster

¨ Cytomegalovirus

¨ Candidosis

¨ Histoplasmosis

¨ Pneumocystis carnii pneumonia

¨ Toxoplasmosis

¨ Tuberculosis

 

Oral Manifestations of HIV

 

The Acquired Immune Deficiency Syndrome is an increasingly common disease, characterised by a severe defect of cell-mediated immunity causing susceptibility to infection, tumours and neurological disease.