The medical officer of health is urging residents of Windsor-Essex to get vaccinated against the measles.
Dr. Mehdi Aloosh says since the first case of the highly contagious disease in February, there have been 70 confirmed cases, mostly in the Leamington and Kingsville area.
Dr. Aloosh says measles is easily spread among unvaccinated populations.
The health unit says a high percentage of the current cases involve school-aged children.
He says the region has seen severe cases.
"We had cases who have been hospitalized, so we have seen severe cases in Windsor-Essex. This is in line with the province that has been seeing hospitalization cases. So we are not very different from the rest of the province."
Dr. Aloosh says most cases are in the county.
"The majority of cases reside in Leamington and Kingsville area which talks about the problem of the unvaccination rate. But, I'm concerned that this goes over to other communities."
He says those under the age of five are mainly affected.
"So it's very difficult to say that for who's affected. But from our experience, younger in here in Windsor-Essex has been most affected severely and going to hospital."
Officials say to help prevent the spread of the illness, if a case is confirmed in a classroom any student who has not received two doses of the M-M-R vaccine will be excluded from school for up to 21 days.
The health unit also advises people to stay home when they're not feeling well.
Holy Week and the Easter weekend traditionally involves large gatherings which public health officials say could lead to a very high transmission of the virus.
-with files from CTV Windsor's Bob Bellacicco