patient zero

Originally patient O (standing for out of California), referring to Gaëtan Dugas, a superspreader of AIDS who was at the time erroneously believed to have introduced the virus to the United States. The letter O was later misinterpreted as a zero.

patient zero (plural patient zeros or patient zeroes)

1. (epidemiology) The initial patient in the population of an epidemiological investigation.

   Synonyms: index case, index patient

For quotations using this term, see Citations:patient zero.

• patient 0