Hygiene refers to conditions and practices that help to maintain health and prevent the spread of diseases. Medical hygiene therefore includes a specific set of practices associated with this preservation of health, for example environmental cleaning, sterilization of equipment, hand hygiene, water and sanitation and safe disposal of medical waste.

The human immunodeficiency virus (HIV) targets cells in the immune system – the body’s defence against illness – and weakens the body’s ability to fight against infections and some types of cancer. The virus destroys white blood cells in the immune system called CD4 cells and replicates itself inside these cells.