HUMAN IMMUNODEFICIENCY VIRUS

Between two weeks and several months following infection, seroconversion may result in an acute self-limited illness, similar to infectious mononucleosis, lasting for a week or two. Infected people may then be free of symptoms or clinical signs for many months to years before other clinical manifestations appear.

acquired immune deficiency syndrome (AIDS) represents the late clinical stage of infection with HIV, which most often results in progressive damage to the immune system, resulting in opportunistic infections and malignancies, constitutional and neurological disorders and other organ damage.

The concentration of HIV in the bloodstream is very high in the early stages of infection, including the window period between acquisition of HIV and the seroconversion illness. After the resolution of this illness, HIV viral load decreases due to host immune responses and stabilises at a lower level. As immunodeficiency progresses and AIDS develops the HIV viral load rises again. Viral load is also influenced by antiretroviral therapy. Most patients on combination antiretroviral therapy have low HIV viral load.

Infectivity is believed to begin shortly after primary infection and continue throughout life, irrespective of whether the patient is symptomatic. Infective HIV particles are present in the blood, semen and other body fluids of infected individuals.

HIV is a blood borne and sexually transmissible virus. HIV may be transmitted by direct contact with blood or other body fluids, through mucous membranes, nonintact skin or through percutaneous injury. Needle stick injury with HIV positive blood has resulted in sero-conversion ranging from 0-0.42% in various studies.

Standard precautions are sufficient to prevent HIV transmission.

Additional precautions for patients with HIV are required only for those patients with opportunistic infections such as pulmonary tuberculosis.

HIV is sensitive to many chemical disinfectants including aldehydes. A variety of studies have shown that when the virus is protected within a dried protein coagulum, some chemical disinfectants including 1% glutaraldehyde will fail to inactivate the virus within 5 minutes. However, in another series of studies in which the surface and internal channels of endoscopes were contaminated with high titre HIV serum, simple manual cleaning removed HIV activity from all except a single endoscope. The remaining viral activity was removed from this endoscope after 10 minutes or less in 2% glutaraldehyde.

Where endoscopes were sampled after removal from HIV positive patients, all HIV present on endoscopes was removed by manual cleaning alone. This emphasises the absolute necessity to ensure that scrupulous manual cleaning removes all traces of blood and proteinaceous material. such cleaning should be undertaken without delay.