index patient

American  

[in-deks pey-shuhnt] / ˈɪn dɛks ˌpeɪ ʃənt /

noun

Pathology.

1. the first person known to have a particular disease or other medical condition in a population, especially the first patient in an epidemic known to have contracted the infection.

   The index patient did not immediately test positive, and consequently spread the virus for several days.

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Etymology

Origin of index patient

First recorded in 1950–55

Example Sentences

The Portuguese researchers sequenced the virus from a sample collected on 4 May, which means the infected person likely had no connection to the index patient in the United Kingdom.

From Science Magazine

The CDC had requested brain tissue and cerebrospinal samples for any new cases so they could see if it was a fungus matching the one in the index patient’s body.

From Washington Times

Scientists concluded that that person infected two other families sitting at neighboring tables about three feet away; they suspect that infected droplets from the index patient hitched a ride on air flows powered by an air-conditioning system.

From Los Angeles Times

More infections cropped up on the index patient's team, which the CDC said may have been from more exposure in their separate locker room and sitting closely together on the bench.

From Fox News

The index patient, or believed source of infection, had a fever, cough, sore throat and headache a day after playing in the June 16 game in Tampa Bay, Fla., per the study.

From Fox News