Oesophageal herpes. Endoscope view of blisters (red) and plaques (yellow) due to a herpes infection in the oesophagus of an AIDS patient. AIDS (acquired immune deficiency syndrome) is caused by HIV (human immunodeficiency virus). HIV invades and destroys lymphocyte white blood cells, which severely damages the immune system. This makes other infections more serious. Herpes viruses can cause cold sores and genital herpes. However, in patients with weakened immune systems, such as those with AIDS or those on immunosuppressant drugs, infections may affect the whole body, which can be fatal.