This mysterious pathogen appeared from nowhere, a complete surprise. No one knows how long it had been doing its work in the dark until the first revealing signs showed up in 1981. Doctors in San Francisco came across strange findings. A number of men from the homosexual subculture had come down with an extremely rare form of pneumonia as well as with a type of skin cancer that had almost never been seen before. All of the patients had extremely high fever, and most of them died after a brief time.

HI viruses

The sick men had strikingly few T helper cells in their blood, an indication of an unknown immunodeficiency illness. As only homosexual men were affected, people spoke for a time of the "gay epidemic." A serious error, as it turned out. The number of cases began to increase at an alarming rate, and it did not take long to discover that heterosexuals were also susceptible to the disease. It was later given the neutral designation AIDS, Acquired Immune Deficiency Syndrome. Scientists discussed the possibility of a virus which had not yet been detected as the cause.

AIDS, the Scourge of Humankind
Over the course of the following years, AIDS became one of the most feared scourges of the human race. As of the end of 2000, 25 million people had died, according to statistics from the WHO. About 40 million are infected or have already developed the illness. Poorer countries, especially in southern Africa, have been hit hardest. But even the more prosperous nations report a disturbing number of new infections every year.

New Infections in 2001:

AIDS and HIV
AIDS is a serious weakening of the body's own immune system. It is caused by the human immunodeficiency virus, abbreviated HIV. AIDS makes the organism susceptible to all sorts of infectious and cancerous diseases which a healthy human being normally deals with without any trouble. Over the course of time, these illnesses result in death.

Infection
HI viruses are transmitted when they are carried over into the blood system of another person through the mucous membranes or small injuries along with blood, sperm or vaginal secretions. Most HIV infections can be traced back to unprotected sexual intercourse.

Symptoms
Following the HIV infection, there are a number of stages to the illness.

• HIV positives, people who have been shown to have antibodies against the HI virus in their bodies, only have temporary signs of illness initially. They suffer from symptoms similar to the flu, usually weeks after the infection, but these symptoms disappear again after a time without further treatment.
  
• There follows a period without any symptoms which can last for a number of years.
  
• In the preliminary stage of AIDS, the first secondary infections appear, accompanied by fever and diarrhoea.
  
• The last stage is also known as full-blown AIDS. The patients become emaciated. They suffer from serious infections caused by viruses, bacteria and fungi. Severe lung and cancer diseases are typical for this stage.