Index case

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The index case or patient zero is the first documented patient in a disease epidemic within a population, [1] or the first documented patient included in an epidemiological study. [2] It can also refer to the first case of a condition or syndrome (not necessarily contagious) to be described in the medical literature, whether or not the patient is thought to be the first person affected.[ citation needed ] An index case can achieve the status of a "classic" case study in the literature, as did Phineas Gage, the first known person to exhibit a definitive personality change as a result of a brain injury. [3]

Contents

Term

The index case may or may not indicate the source of the disease, the possible spread, or which reservoir holds the disease in between outbreaks, but may bring awareness of an emerging outbreak. [4] [5] Earlier cases may or may not be found and are labeled primary or coprimary, secondary, tertiary, etc. [4] The term primary case can only apply to infectious diseases that spread from human to human, and refers to the person who first brings a disease into a group of people. [5] In epidemiology, the term is often used by both scientists and journalists alike to refer to the individual known or believed to have been the first infected or source of the resulting outbreak in a population as the index case, but such would technically refer to the primary case. [5] [6]

Origin of patient zero

"Patient zero" was used to refer to the supposed source of HIV outbreak in the United States, flight attendant Gaëtan Dugas in the popular press, but the term's use was based on a misunderstanding (and Dugas was not the index case). [7] In the 1984 study of Centers for Disease Control and Prevention (CDC), one of the earliest recorded HIV-patients was code-named "patient O", which stands for "patient out of California". The letter O, however, was interpreted by some readers of the report as the numeral 0. The designation patient zero (for Gaëtan Dugas) was subsequently propagated by the San Francisco Chronicle journalist Randy Shilts in his book And the Band Played On in 1987. William Darrow, behavioral scientist of CDC responsible to figure out why gay men in Los Angeles were dying of a strange illness, said: "That's correct. I never labeled him Patient Zero". [8]

The term has been expanded into general usage to refer to an individual identified as the first carrier of a communicable disease in a population (the primary case) or pandemics, or the first incident in the onset of a catastrophic trend. [9] [10] In some cases, a known or suspected patient zero may be informally referred to as an index case for the purpose of a scientific study, such as the two-year-old boy in a remote village in Guinea who was thought to be the source of the largest Ebola virus outbreak in history, [2] [11] or an unknown one, such as the mysterious patient zero of COVID-19. [12] [13]

In genetics, the index case is the case of the original patient (i.e. propositus or proband ) that stimulates investigation of other members of the family to discover a possible genetic factor. [14]

The term can also be used in non-medical fields to describe the first individual affected by something negative that since propagated to others, such as the first user on a network infected by malware. [15]

Examples

Gaëtan Dugas

A 1984 paper linked 40 AIDS patients by sexual contact. Of those patients, Dugas was supposedly the first to experience an onset of symptoms of AIDS. In the above graph, Dugas is represented by the circle labeled 0, highlighted in red. AIDS index case graph.svg
A 1984 paper linked 40 AIDS patients by sexual contact. Of those patients, Dugas was supposedly the first to experience an onset of symptoms of AIDS. In the above graph, Dugas is represented by the circle labeled 0, highlighted in red.

In the early years of the AIDS epidemic, a patient zero transmission scenario was compiled by William Darrow and colleagues at the United States Centers for Disease Control and Prevention (CDC). [17] This epidemiological study showed how patient zero had infected multiple partners with HIV, and they, in turn, transmitted it to others causing rapid spread of the virus to locations all over the world (Auerbach et al., 1984). The CDC identified Gaëtan Dugas as a carrier of the virus from Europe to the United States, who spread it to other men he had sexual contact with at gay bathhouses. [18]

Journalist Randy Shilts subsequently wrote about patient zero, based on Darrow's findings, [17] in his 1987 book And the Band Played On , which identified patient zero as being Gaëtan Dugas. [19] Dugas was a flight attendant who was sexually promiscuous in several North American cities, according to Shilts' book. He was vilified for several years as a "mass spreader" of HIV, and was seen as the original source of the HIV epidemic among homosexual men. Four years later, Darrow repudiated the study's methodology and how Shilts had represented its conclusions. [17]

A 2007 study by Michael Worobey and Arthur Pitchenik published in the Proceedings of the National Academy of Sciences of the United States of America claimed that, based on the results of genetic analysis, current North American strains of HIV probably moved from Africa to Haiti before entering the United States around 1969, [20] probably through a single immigrant. However, a teenager named Robert Rayford died in St. Louis, Missouri, possibly of complications from AIDS in 1969, having most likely become infected with the virus before 1966. This would imply that there were prior carriers of HIV-strains in North America. [21] [22]

The phrase patient zero is now used in the media to refer to the primary case for infectious disease outbreaks, as well as for computer virus outbreaks, and more broadly, as the source of ideas or actions that have far-reaching consequences. [23] [24] [25] [26] [27]

David Heymann, professor of Infectious Disease Epidemiology at the London School of Hygiene & Tropical Medicine, and formerly with the World Health Organization (WHO), [28] has questioned the importance of finding patient zero, stating, "Finding patient zero may be important in some instances, but only if they are still alive and spreading the disease; and more often than not, especially in large disease outbreaks, they're not." [29]

Others

Non-medical usage

The term is used to identify the first computer or user to be infected with malware on a network, which then infected other systems. [15] [41]

Monica Lewinsky has described herself as the "patient zero" of online harassment, meaning that she was the first person to receive widespread public harassment via the internet. [42]

See also

Related Research Articles

<span class="mw-page-title-main">Gaëtan Dugas</span> Canadian flight attendant, long misidentified as the index case of the North American AIDS Crisis

Gaëtan Dugas was a Québécois Canadian flight attendant and a relatively early patient with the human immunodeficiency virus (HIV), who once was widely described as "Patient Zero", accusing him of introducing HIV to the United States. This claim has since been proven incorrect.

The spread of HIV/AIDS has affected millions of people worldwide; AIDS is considered a pandemic. The World Health Organization (WHO) estimated that in 2016 there were 36.7 million people worldwide living with HIV/AIDS, with 1.8 million new HIV infections per year and 1 million deaths due to AIDS. Misconceptions about HIV and AIDS arise from several different sources, from simple ignorance and misunderstandings about scientific knowledge regarding HIV infections and the cause of AIDS to misinformation propagated by individuals and groups with ideological stances that deny a causative relationship between HIV infection and the development of AIDS. Below is a list and explanations of some common misconceptions and their rebuttals.

<i>Zero Patience</i> 1993 musical Canadian film by John Greyson

Zero Patience is a 1993 Canadian musical film written and directed by John Greyson. The film examines and refutes the urban legend of the alleged introduction of HIV to North America by a single individual, Gaëtan Dugas. Dugas, better known as Patient Zero, was the target of blame in the popular imagination in the 1980's in large measure because of Randy Shilts's American television film docudrama, And the Band Played On (1987), a history of the early days of the AIDS epidemic. Zero Patience tells its story against the backdrop of a romance between a time-displaced Sir Richard Francis Burton and the ghost of "Zero".

This is a timeline of HIV/AIDS, including cases before 1980.

<span class="mw-page-title-main">History of HIV/AIDS</span> Epidemiological history

AIDS is caused by a human immunodeficiency virus (HIV), which originated in non-human primates in Central and West Africa. While various sub-groups of the virus acquired human infectivity at different times, the present pandemic had its origins in the emergence of one specific strain – HIV-1 subgroup M – in Léopoldville in the Belgian Congo in the 1920s.

Donald Pinkston Francis is an American epidemiologist who worked on the Ebola outbreak in Africa in the late 1970s, and as an HIV/AIDS researcher. He retired from the U.S. Public Health Service in 1992, after 21 years of service. He lives in San Francisco, California.

Arne Vidar Røed, known in medical literature by the anagram Arvid Darre Noe, was a Norwegian sailor and truck driver who contracted one of the earliest confirmed cases of HIV/AIDS. His was the first confirmed HIV case in Europe though the disease was not identified at the time of his death.

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The situation with the spread of HIV/AIDS in Russia is described by some researchers as an epidemic. The first cases of human immunodeficiency virus infection were recorded in the USSR in 1985-1987. Patient zero is officially considered to be a military interpreter who worked in Tanzania in the early 1980s and was infected by a local man during sexual contact. After 1988—1989 Elista HIV outbreak, the disease became known to the general public and the first AIDS centers were established. In 1995-1996, the virus spread among injecting drug users (IDUs) and soon expanded throughout the country. By 2006, HIV had spread beyond the vulnerable IDU group, endangering their heterosexual partners and potentially the entire population.

<i>And the Band Played On</i> (film) 1993 American television film by Roger Spottiswoode

And the Band Played On is a 1993 American television film docudrama directed by Roger Spottiswoode. The teleplay by Arnold Schulman is based on the best-selling 1987 non-fiction book And the Band Played On: Politics, People, and the AIDS Epidemic by Randy Shilts, and is noteworthy for featuring both a vast historical scope, as well as an exceptionally sprawling cast.

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<i>And the Band Played On</i> 1987 book by Randy Shilts

And the Band Played On: Politics, People, and the AIDS Epidemic is a 1987 book by San Francisco Chronicle journalist Randy Shilts. The book chronicles the discovery and spread of the human immunodeficiency virus (HIV) and acquired immune deficiency syndrome (AIDS) with a special emphasis on government indifference and political infighting—specifically in the United States—to what was then perceived as a specifically gay disease. Shilts's premise is that AIDS was allowed to happen: while the disease is caused by a biological agent, incompetence and apathy toward those initially affected allowed its spread to become much worse.

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<span class="mw-page-title-main">Ebola</span> Viral hemorrhagic fever of humans and other primates caused by ebolaviruses

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<span class="mw-page-title-main">Western African Ebola virus epidemic</span> 2013–2016 major disease outbreak

The 2013–2016 epidemic of Ebola virus disease, centered in Western Africa, was the most widespread outbreak of the disease in history. It caused major loss of life and socioeconomic disruption in the region, mainly in Guinea, Liberia and Sierra Leone. The first cases were recorded in Guinea in December 2013; later, the disease spread to neighbouring Liberia and Sierra Leone, with minor outbreaks occurring in Nigeria and Mali. Secondary infections of medical workers occurred in the United States and Spain. In addition, isolated cases were recorded in Senegal, the United Kingdom and Italy. The number of cases peaked in October 2014 and then began to decline gradually, following the commitment of substantial international resources.

<span class="mw-page-title-main">Ebola virus epidemic in Sierra Leone</span>

An Ebola virus epidemic in Sierra Leone occurred in 2014, along with the neighbouring countries of Guinea and Liberia. At the time it was discovered, it was thought that Ebola virus was not endemic to Sierra Leone or to the West African region and that the epidemic represented the first time the virus was discovered there. However, US researchers pointed to lab samples used for Lassa fever testing to suggest that Ebola had been in Sierra Leone as early as 2006.

<span class="mw-page-title-main">Ebola virus epidemic in Liberia</span> Health disaster in Africa

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<span class="mw-page-title-main">Ebola virus disease in Mali</span>

Ebola virus disease in Mali occurred in October 2014, leading to concern about the possibility of an outbreak of Ebola in Mali. A child was brought from Guinea and died in the northwestern city of Kayes. Mali contact traced over 100 people who had contact with the child; tracing was completed in mid-November with no further cases discovered. In November, a second unrelated outbreak occurred in Mali's capital city, Bamako. Several people at a clinic are thought to have been infected by a man traveling from Guinea. On January 18, Mali was declared Ebola-free after 42 days with no new cases. There had been a cumulative total of eight cases with six deaths.

<span class="mw-page-title-main">Ebola in Nigeria</span>

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<i>Killing Patient Zero</i> 2019 Canadian documentary film

Killing Patient Zero is a Canadian documentary film, directed by Laurie Lynd and released in 2019. The film is a portrait of Gaëtan Dugas, the Canadian man who was one of the earliest diagnosed HIV/AIDS patients in North America, but became incorrectly demonized as "patient zero" for the epidemic after his role in the early story of the disease was used to illustrate contact tracing in Randy Shilts's 1987 book And the Band Played On.

References

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  15. 1 2 "Search for patient zero: uncovering malware infection at the source". Infosecurity Magazine. 10 July 2012. Archived from the original on 31 March 2017. Retrieved 31 March 2017. Medical researchers look for patient zero to find out where a virus outbreak started and what places and people patient zero came into contact with in order to contain the outbreak and prevent further infections. Similarly, infosec researchers need to look for the user who first introduced the malware into the network, which application was carrying the malware, and the files that are causing it to spread in order to contain it, eliminate it, and prevent reinfection, explained Huger, vice president of development at Sourcefire's cloud technology group.
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  39. ↑ ""I'm back in action," One of the first Americans who contracted COVID-19 speaks about his recovery". 13 March 2021.
  40. ↑ Duarte F. "Who is 'patient zero' in the coronavirus outbreak?". www.bbc.com.
  41. ↑ Savitz E (5 June 2012). "Finding Patient Zero: The Key To Responding To Malware Attacks". Forbes. Archived from the original on 31 March 2017. Retrieved 31 March 2017. In the physical world, the first thing researchers look for during an outbreak is patient zero. Where did the virus start and where are all of the places and who are all of the people it could have touched? In the cyber world this almost never happens. But it is just as fundamental.
  42. ↑ Merica D (October 21, 2014). "Lewinsky makes emotional plea to end cyberbullying". CNN. Archived from the original on October 22, 2014. Retrieved October 22, 2014.
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