Measles jumps by 65 cases in Elgin and Oxford Counties, totalling above 1,200 across Ontario

The measles outbreak continues to spread across the province, with cases climbing in Elgin and Oxford counties.

Southwestern Public Health is reporting 65 additional cases on Thursday, bringing the total to 451 for the region since Oct. 30.

"This sharp rise in cases may be concerning to the community. However, the majority of these cases are part of a group of cases we are investigating that are linked to one another," said Dr. Ninh Tran, medical officer of health for Southwestern Public Health.

"This is a good example of how quickly measles can spread in groups where there are unvaccinated individuals," he said, noting linked cases can be from exposure in large households or gatherings.

Last week, the health unit posted 28 new cases, signalling the ongoing outbreak continues.

"The key message is still measles is out there circulating in our community, and the best thing anyone can do is to be vaccinated because the vast majority of our cases are those who aren't up to date on it," said Ninh.

The majority of cases are among people under 18 years old who are not vaccinated. About 35 patients have been hospitalized due to the severity of their illness in the region, totalling 84 hospitalizations across the province.

Symptoms that could lead to hospitalization are dehydration, need for fever control, or a secondary infection such as pneumonia, Ninh said. Local hospital stays have been between one and 11 days, with an average of three days.

Measles is a highly contagious respiratory virus and primary symptoms are a cough, red watery eyes, fever and a blotchy rash, according to Public Health Ontario.

Those exposed to the virus should monitor for respiratory, GI or conjunctivitis symptoms and stay home if any symptoms arise to reduce exposure to others. Rashes are one of the last symptoms to appear after exposure, Ninh said.

"Symptoms can appear up to 21 days after being exposed to the virus and you may remain infectious until the fifth day after the rash appears," he said.

WATCH: Measles outbreak cause for concern

Experts say a drop in vaccination rates has allowed the spread of the contagious, preventable illness. Many are calling on the Alberta government to inform the public with more public health messaging, and provide better access to vaccines with mass immunization clinics.

The measles outbreak has been traced to a Mennonite wedding in New Brunswick, Ontario's chief public health doctor said, and has since spread across the country. It's the largest measles outbreak Canada has seen in more than a decade.

"The risk of measles remains in our community and it continues to affect unvaccinated and school aged children predominantly," Tran said.