Patient Zero, also known as the index case, is a medical term used to describe the original source of an outbreak of a contagious illness within a population (that is, the origin of the outbreak from whom all other infections are ultimately derived) or to the most significant case within the population. The term "patient zero" was initially used in the investigation into the causes of the outbreak of HIV and AIDS in North America. The most famous example of a "patient zero" is Typhoid Mary.
The first patient zero was a Canadian named Gaetan Dugas, a highly promiscuous homosexual who claimed to have sex with approximately 250 men each year, and over 2,500 sex partners in his lifetime. His work as a flight attendant took him to many cities and afforded him more sexual partners. The U.S. Centre for Disease Control linked him to 40 of the first 248 cases of AIDS in North America.
In June 1980, Dugas was diagnosed with Kaposi's Sarcoma, a viral infection considered a common symptom of the AIDS virus. After his diagnosis, Dugas was warned that this could be caused and spread by a sexually transmitted virus, but he selfishly refused to stop having unprotected sex, claiming that he could do what he wanted with his body. According to Randy Shilts, he allegedly informed some of his sex partners, just after having sex, that he had the "gay cancer" and perhaps they would get it too.
Dugas died in Quebec City on March 30, 1984 as a result of kidney failure caused by continual AIDS-related infections. The total number of infections and deaths attributed to Degas has never been established.
- Typhoid Mary Encyclopedia Britannica http://www.britannica.com/EBchecked/topic/611790/Typhoid-Mary