Index case

The index case or patient zero is the initial patientin the populationsample of an epidemiologicalinvestigation. Patient zero is a somewhat less specific term than index case and is sometimes used to refer to the central patient in an epidemiological investigation rather than the first patient. When used in general to refer to such patients in epidemiological investigations, the term is not capitalized. When the term is used to refer to a specific person in place of that person's name within a report on a specific investigation, the term is capitalized as Patient Zero. Often scientists search for the index case to determine how the diseasespread and what reservoir holds the disease in between outbreaks.

The origin of the term "Patient Zero"

In the early years of the AIDS epidemic, there was a lot of controversy about a so-called Patient Zero who was the basis of a complex transmission scenario compiled by Dr. William Darrow and colleagues at the Center for Disease Control(CDC) in the US. This epidemiological study showed how 'Patient O' (mistakenly identified in the press as 'Patient Zero') had given HIV to multiple partners, who then in turn transmitted it to others and rapidly spread the virus to locations all over the world (Auerbach et al., 1984). In all, at least 40 of the 248 people diagnosed with AIDS by April1982were thought to have had sex either with him or with someone who had.

A journalist, Randy Shilts, subsequently wrote an article based on Darrow's findings in his 1987book And The Band Played On, in which it named Patient Zero as a gay Canadianflight attendantnamed Gaëtan Dugas (February 20, 1953—March 30, 1984[1]). For several years, Dugas was vilified as a "mass spreader" of HIV and the original source of the HIV epidemic among gay men. However, four years after the publication of Shilts's article, Dr. Darrow repudiated his study, admitting that its methods were flawed and that Shilts had misrepresented the study's conclusions.

While Gaëtan Dugas was a real person who did eventually die of AIDS, the Patient Zero story was not much more than myth and scaremongering. HIV in the United States was to a large degree initially spread by gay men, but this occurred on a huge scale over many years, probably a long time before Dugas even began to travel.

Furthermore, later research has cast doubt on the validity of the conclusions that were advanced regarding Dugas's role as a major early transmitter of HIV. At the time, it was believed that the HIV incubated for about one year before becoming AIDS. The patients who were studied due to their contact with patient Zero had AIDS symptoms emerge on an average of eleven months after having had sex with him. Now that the incubation period of the HIV is known to be, on average, longer than 12 months, it is unlikely that any of Patient Zero's sexual partners studied were initially infected by him.

Other Patient Zeros

• Patient Zero was a character in the Canadian film Zero Patience.
• In the third Sliders episode, "Fever", Quinn's double is alleged to be Patient Zero of a global plague.
• The movie Outbreak dealt with government officials charged with finding the index case of an outbreak of an Ebola-like virus .

See also

• Common misconceptions about HIV and AIDS

References

• Auerbach DM, Darrow WW, Jaffe HW, Curran JW. (1984) Cluster of cases of the acquired immune deficiency syndrome. Patients linked by sexual contact. Am J Med. 76, 487-492 PMID 6608269

External links

• Article for the New York Review of Books by Dr. Andrew Moss, Dept. of Epidemiology and International Health, San Francisco, regarding the Patient Zero myth.

it:paziente zero

This article is licensed under the GNU Free Documentation License.
It uses material from the http://en.wikipedia.org/wiki/Index+case Wikipedia article Index case.