People who visited the emergency rooms at Stratford General Hospital, Listowel Memorial Hospital and Wingham and District Hospital may have been exposed to the measles virus.
Huron Perth Public Health said even people who were only at the emergency departments for a short time are at risk of becoming sick due to the highly contagious nature of the illness.
Potential exposure windows:
Stratford General Hospital
Friday, March 28 from 11:10 a.m. until 1:10 p.m.
Listowel Memorial Hospital
Sunday, March 23 from 1:51 p.m. until 9:58 p.m.
Monday, March 24 from 2:13 p.m. until 8:13 p.m.
Friday, March 28 from 9:07 a.m. until 12:21 p.m.
Wingham and District Hospital
Friday, March 28 from 9:39 p.m. until 11:59 p.m.
Saturday, March 29 from 12 a.m. until 1:15 a.m.
Sunday, March 30 from 1:49 p.m. until 6 p.m. and 9 p.m. until 11 p.m.
Measles symptoms can develop seven to 21 days after exposure.
They include a fever, runny nose, cough, red eyes, small white spots on the inside of the mouth and throat and a red, blotchy rash.
Someone with measles is considered to be contagious four days before a rash starts and up until four days after the rash appears.
Health experts are urging anyone who believes they may have measles to call ahead before seeking in-person assessment. Doing so allows health practitioners to put containment protocols in place to protect all patients.
