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Index case

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"Patient zero" redirects here. For other uses, seePatient zero (disambiguation).

Theindex caseorpatient zerois the first documentedpatientin adisease epidemicwithin a population,[1]or the first documented patient included in anepidemiologicalstudy.[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 didPhineas Gage,the first known person to exhibit a definitive personality change as a result of a brain injury.[3]

Term

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The index case may or may not indicate the source of thedisease,the possible spread, or which reservoir holds the disease in betweenoutbreaks,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

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"Patient zero" was used to refer to the supposed source ofHIVoutbreak in theUnited States,flight attendantGaëtan Dugasin 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 ofCenters for Disease Control and Prevention(CDC), one of the earliest recorded HIV-patients was code-named "patient O", which stands for "patientout of California ". The letterO,however, was interpreted by some readers of the report as the numeral0.The designationpatient zero(for Gaëtan Dugas) was subsequently propagated by theSan Francisco ChroniclejournalistRandy Shiltsin his bookAnd the Band Played Onin 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) orpandemics,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 inGuineawho was thought to be the source of thelargest Ebola virus outbreakin history,[2][11]or an unknown one, such as themysterious patient zeroofCOVID-19.[12][13]

In genetics, the index case is the case of the original patient (i.e.propositusorproband) 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 bymalware.[15]

Examples

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Gaëtan Dugas

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Main article:Gaëtan Dugas
A 1984 paper[16]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 theAIDSepidemic,apatient zerotransmission scenario was compiled byWilliam Darrowand colleagues at the United StatesCenters for Disease Control and Prevention(CDC).[17]This epidemiological study showed how patient zero had infected multiple partners withHIV,and they, in turn, transmitted it to others causing rapid spread of thevirusto locations all over the world (Auerbach et al., 1984). The CDC identifiedGaëtan Dugasas a carrier of the virus from Europe to the United States, who spread it to other men he had sexual contact with atgay bathhouses.[18]

JournalistRandy Shiltssubsequently wrote about patient zero, based on Darrow's findings,[17]in his 1987 bookAnd 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 amonghomosexual 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 theProceedings of the National Academy of Sciences of the United States of Americaclaimed that, based on the results ofgenetic analysis,current North American strains of HIV probably moved fromAfricatoHaitibefore entering the United States around 1969,[20]probably through a singleimmigrant.However, a teenager namedRobert Rayforddied inSt. Louis,Missouri,possibly of complications from AIDS in 1969, having most likely become infected with the virusbefore1966. 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 theWorld 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

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  • Mary Mallon( "Typhoid Mary" ) was an index case of atyphoidoutbreak in the early 1900s. An apparently healthy carrier, she infected at least 47 people while working as acook.She eventually was isolated to prevent her from spreading the disease to others.[30]
  • The first recorded victim ofEbolawas a 44-year-old schoolteacher named Mabalo Lokela, who died on 8 September 1976, 14 days after symptom onset.[31]
  • 64-year-oldLiu Jianlun,aGuangdongdoctor, transmittedSARSinternationally by infecting othersuper-spreadersduring a stay in theHong KongMetropole Hotel in 2003.[32][33]
  • A baby in the Lewis House at 40 Broad Street, named Frances Lewis, is considered the index patient in the1854 cholera outbreakin the Soho neighbourhood ofLondon.(The Ghost Map,Steven Johnson,2005.)[34]
  • Édgar Enrique Hernández may be patient zero of the2009 flu pandemic.[35]He recovered, and a bronze statue has been erected in his honor.[36]Maria Adela Gutierrez, who contracted the virus about the same time as Hernández, became the first officially confirmed fatality.
  • One-year-oldEmile Ouamounois believed to be patient zero in the 2014 Ebola epidemic inGuinea and West Africa.[37]
  • 51-year-old Jesus Lujan was the index case of the1924 Los Angeles pneumonic plague outbreakwhich killed 33.[38]
  • As for theCOVID-19 pandemic,there are many known "patient zeros" across the world known for different symptoms and stories. Out of Los Angeles, patient zero Gregg Garfield spent 64 days in the hospital, including 30 days of coma-state after contracting the virus on a ski trip. Doctors said he had a 1% chance to live. He survived, but had fingers and toes amputated.[39]
  • Another patient zero of the COVID-19 pandemic includes an elderly man who was diagnosed on 1 December 2019, someone who had no contact with theHuanan Seafood Wholesale Market.Three other people experienced symptoms in the following days who also did not have contact with the Market.[40]

Non-medical usage

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

Monica Lewinskyhas 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

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References

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  1. ^"Diseases – Activity 1 – Glossary, page 3 of 5".science.education.nih.gov.Archivedfrom the original on 10 November 2017.Retrieved10 November2017.
  2. ^ab"WordNet Search – 3.0".Princeton University, wordnetweb.princeton.edu.Archivedfrom the original on 3 March 2012.Retrieved3 November2010.
  3. ^"Why Brain Scientists Are Still Obsessed With The Curious Case Of Phineas Gage".NPR.org.Archivedfrom the original on 28 August 2019.Retrieved18 November2017.
  4. ^ab"Sporadic STEC O157 Infection: Secondary Household Transmission in Wales".CDC.gov.Centers for Disease Control and Prevention, USA. 1 January 1994.Archivedfrom the original on 28 May 2010.Retrieved3 November2010.
  5. ^abcGiesecke J (2014). "Primary and index cases".The Lancet.384(9959): 2024.doi:10.1016/s0140-6736(14)62331-x.PMID25483164.S2CID12454399.
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  7. ^Davis N (27 October 2016)."Gaétan Dugas: 'patient zero' not source of HIV/Aids outbreak, study confirms".The Guardian.Archivedfrom the original on 27 October 2016.Retrieved26 October2016.
  8. ^DOUCLEFF M (26 October 2016)."Researchers Clear 'Patient Zero' From AIDS Origin Story".NPR.Archivedfrom the original on 30 April 2021.Retrieved1 May2021.
  9. ^"Patient Zero – definition of Patient Zero in the Medical dictionary – by the Free Online Medical Dictionary, Thesaurus and Encyclopedia".medical-dictionary.thefreedictionary.com.Archivedfrom the original on 24 February 2021.Retrieved3 November2010.
  10. ^"patient zero | Definition of patient zero in English by Oxford Dictionaries".Oxford Dictionaries | English.Archived fromthe originalon 1 December 2017.Retrieved18 November2017.
  11. ^"Ebola outbreak: 'Patient zero' at start of deadly virus spread".The Independent.11 August 2014.Archivedfrom the original on 1 December 2017.Retrieved18 November2017.
  12. ^Page J, Hinshaw D, McKay B (26 February 2021)."In Hunt for Covid-19 Origin, Patient Zero Points to Second Wuhan Market – The man with the first confirmed infection of the new coronavirus told the WHO team that his parents had shopped there".The Wall Street Journal.Retrieved27 February2021.
  13. ^Duarte F (24 February 2020)."As the cases of coronavirus increase in China and around the world, the hunt is on to identify" patient zero "".BBC News.Retrieved22 March2020.
  14. ^"Definition of index case".The free medical dictionary by farlex.Archivedfrom the original on 12 May 2013.Retrieved11 May2013.
  15. ^ab"Search for patient zero: uncovering malware infection at the source".Infosecurity Magazine.10 July 2012.Archivedfrom the original on 31 March 2017.Retrieved31 March2017.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.
  16. ^Auerbach DM,Darrow WW,Jaffe HW,Curran JW(1984). "Cluster of cases of the acquired immune deficiency syndrome. Patients linked by sexual contact".The American Journal of Medicine.76(3): 487–92.doi:10.1016/0002-9343(84)90668-5.PMID6608269.
  17. ^abc"The Origin of HIV and the First Cases of AIDS".avert.org.AVERT.Archivedfrom the original on 4 November 2010.Retrieved3 November2010.
  18. ^Pence, G. E. (2008). Preventing the Global Spread of AIDS. In Medical Ethics Accounts of the Cases That Shaped and Define Medical Ethics (p. 331). New York, USA, McGraw-Hill.
  19. ^Matt & Andrej Koymasky - Famous GLTB - Gaëtan DugasArchivedDecember 14, 2005, at theWayback Machine
  20. ^Bowdler N (30 October 2007)."Key HIV strain 'came from Haiti'".BBC News.Archivedfrom the original on 21 May 2012.Retrieved5 May2010.
  21. ^"HIV Spread from Haiti to NYC in 1970".The Scientist.Archivedfrom the original on 10 July 2021.Retrieved10 July2021.
  22. ^Worobey, Michael et al "1970s and 'Patient 0' HIV-1 genomes illuminate early HIV/AIDS history in North America" Nature (2016) doi:10.1038/nature19827
  23. ^"Have Doctors Found Swine" Patient Zero? "".CBS News.29 April 2009.Archivedfrom the original on 29 April 2009.Retrieved29 April2009.
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  27. ^"That Man in the White House".The Weekly Standard. 28 November 2003. Archived fromthe originalon 4 June 2011.Retrieved3 November2010.
  28. ^"WHO | Members of, and Advisers to, the International Health Regulations (2005) Emergency Committee on Zika virus and observed increase in neurological disorders and neonatal malformations".WHO.Archivedfrom the original on 21 April 2019.Retrieved25 December2019.
  29. ^Mohammadi D (15 January 2015)."Finding patient zero".The Pharmaceutical Journal.294(7845).Archivedfrom the original on 24 January 2015.Retrieved16 January2015.
  30. ^"NOVA | The Most Dangerous Woman in America | In Her Own Words".PBS.11 November 1938.Archivedfrom the original on 26 April 2010.Retrieved3 November2010.
  31. ^Report of an International Commission (1978)."Ebola haemorrhagic fever in Zaire, 1976"(PDF).Bull. World Health Organ.56(2): 271–93.PMC2395567.PMID307456.Archived fromthe original(PDF)on 8 August 2014.Retrieved22 May2018.
  32. ^"How SARS changed the world in less than six months"(PDF).Bulletin of the World Health Organization.81(8). 2003.Archived(PDF)from the original on 5 April 2012.Retrieved18 October2011.
  33. ^Laurance J (24 April 2003)."One family went on holiday – and made Toronto a global pariah".The Independent.London.Archivedfrom the original on 22 May 2018.Retrieved5 May2010.
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  35. ^"Have Doctors Found Swine" Patient Zero? "".CBS News.29 April 2009.Archivedfrom the original on 5 August 2011.Retrieved3 November2010.
  36. ^"Statue erected of first boy in world who caught swine flu".mirror.co.uk.Mirror.Archivedfrom the original on 22 May 2014.Retrieved25 April2009.
  37. ^Beukes S (28 October 2014)."Finding Ebola's 'patient zero'".The Guardian.Archivedfrom the original on 19 December 2014.Retrieved28 November2014.
  38. ^Feldinger F (2008).A slight epidemic: the government cover-up of black plague in Los Angeles: what happened and why it matters.Los Angeles, CA: Silver Lake Pub. pp. 124–130.ISBN978-1-56343-885-1.
  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.Archivedfrom the original on 31 March 2017.Retrieved31 March2017.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 (21 October 2014)."Lewinsky makes emotional plea to end cyberbullying".CNN.Archivedfrom the original on 22 October 2014.Retrieved22 October2014.
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