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index case

index case

1 6.7
First known person in an outbreak who helps trace where the disease came from
  • noun
  • /ˈɪndɛks keɪs/
  • Specialized
translation icon : caso índice
  • The researchers identified the index case, which helped them track the outbreak more effectively.
  • index case-patient
  • reported index case
  • index case is reported

Which is the index case for Alzheimer's disease.

Examples

  • Interventions applied only to index cases are rather inefficient, even with the swiftest reporting.

    Academic text (2015)
  • On day 5 of the illness of the index case-patient, a contact investigation was initiated.

    Academic text (2013)
  • You often have an index case or a pro band, meaning the person who comes to clinical attention.

  • Which is the index case for Alzheimer's disease.

  • When interventions are also applied to secondary cases produced by a reported index case, the interventions become more effective.

    Academic text (2015)
  • High concentrations of SARS-CoV were found in the feces and urine of the person with the index case.

    Academic text (2006)
  • Prophylaxis should ideally be given within 24 hours of the index case presentation and is supplied by the admitting hospital.

    Academic text (2014)
  • The index case-patient had fever, cough, dyspnea, and diarrhea that progressed over 2 days, leading to hospital admission.

    Academic text (2013)
  • The index case-patient was a 49-year-old HIV-positive man for whom smear-positive (2+), culture-positive pulmonary TB was diagnosed.

    Academic text (2015)
  • After studying the index case, the team was able to understand how the disease spread.

Synonyms

patient zero
vsindex case
  • Specialized
3 7.0

First known person infected in an outbreak who may spread the disease to others

is the earliest documented case included in a study to trace the source

Surface Forms

index case singular
index cases plural

Morphology

index + case

The constituents 'index' (an indicator) and 'case' (a person/instance in a study) give a partial clue that this is a marked or notable case, but the specific sense 'earliest documented case' is a specialized, domain-specific use of 'index' that is not directly inferable by a B1 learner from the literal meanings. While some learners might guess it refers to an important or identified case, understanding that it denotes the first/initial case usually requires prior exposure or medical context, so the expression is only partially transparent.

Etymology

The term index case comes from the idea of index as a 'pointer' or the 'first item in a list' and case as a 'person with a disease'. The index case is the first known patient who points to where an outbreak began, so finding them helps trace the source and stop the disease from spreading.