A burgeoning measles outbreak has been detected in southwestern Ontario, primarily affecting unvaccinated children. Health officials have traced the origin of this outbreak back to a Mennonite religious gathering in New Brunswick that took place last fall.

In a letter dated March 7, Dr. Kieran Moore, Ontario's chief medical officer of health, reported that the outbreak began after unknowing attendees at this sizable Mennonite gathering returned home to southwestern Ontario, particularly in areas bordering Norfolk, Oxford, and Elgin counties, which are home to a large conservative Mennonite population.

The outbreak's ripple effects extended beyond Ontario into Manitoba, where cases emerged among Mennonites who had visited family in Ontario and subsequently returned home. It was noted that the measles virus infiltrated Canada on October 16 of last year when an infected traveler arrived in New Brunswick after stops in Vancouver and Toronto from the Philippines. However, pinpointing how the virus ultimately spread within southwestern Ontario had previously eluded health authorities until Dr. Moore's recent disclosures.

According to the latest report from Public Health Ontario, there have been 223 confirmed cases of measles in the Southwestern Public Health region, with an additional 111 confirmed cases in the Grand Erie area. Alarmingly, these figures account for nearly 75% of all confirmed measles cases across Ontario, with the vast majority occurring amongst unvaccinated residents.

In Texas, similar outbreaks have been noted, attributed to low vaccination rates particularly within Mennonite communities. Interestingly, while health officials in southwestern Ontario have not publicly addressed vaccine hesitancy as a direct reason for the outbreak, the evidence suggests it plays a significant role. Exposure sites in Grand Erie have been linked to a church and several private Christian schools serving Old Colony Mennonites.

Dr. Moore highlighted, “Cases could spread in any unvaccinated community or population but are disproportionately affecting some Mennonite, Amish, and other Anabaptist communities due to a combination of under-immunization and exposure to measles in certain areas.”

During the COVID-19 pandemic, leaders from Mennonite Church Canada sought to clarify their stance on vaccinations, stating that no biblical or church doctrine justified religious exemptions from vaccines. However, a spokesperson for the Mennonite Church in the eastern chapter—which includes Ontario and New Brunswick—clarified that the Old Colony Mennonites are not affiliated with their denomination, leading to ambiguities regarding their current messaging on measles vaccinations.

Moreover, health officials are reinforcing the importance of vaccination, urging all residents born after 1970 to receive two doses of the measles, mumps, and rubella (MMR) vaccine. This vaccine is typically administered just after a child's first birthday, with a second dose between ages four to six. In areas heavily affected by the outbreak, such as Southwestern and Grand Erie, infants can receive their first dose as early as six months.

It has also been emphasized that additional vaccines are being procured as needed to manage the situation. To date, measles cases have emerged across 11 health units and the city of Hamilton, with links back to the southwestern Ontario outbreak.

While most individuals who contract measles will recover at home, the virus poses serious health risks, including potential brain damage, deafness, and in sadder cases, fatalities, as demonstrated by a child who tragically died from measles in Hamilton last year.

As the situation evolves, officials stress that vaccination remains the most effective way to protect against this highly contagious virus. Community leaders and health officials continue to encourage open discussions around vaccination to combat misinformation and foster a safer environment for all.