Mpox: Montreal public health warns of new cases

Bavarian Nordic’s Jynneos mpox vaccine.

Montreal Public Health is warning of a slight uptick in mpox in recent weeks and is calling for increased vigilance.

In a memo published last Thursday for health-care professionals and partners, the agency said it recorded six new mpox cases in the last few weeks, for a total of nine cases so far in 2025.

Last year, Montreal Public Health recorded 38 mpox cases compared to 11 in 2023. During the 2022 mpox outbreak, 400 cases were diagnosed in the city.

It said four of the six recent cases were transmitted within the city, while the other two may have been infected abroad.

“As with the outbreaks in 2022 and autumn 2024, transmission mainly involves men who have sex with men. All cases were infected with the clade 2b virus (the same clade as in 2022),” the memo said. “Vaccinated cases are generally less symptomatic than unvaccinated cases.”

The memo also urged health-care workers to stay vigilant and encourage mpox vaccination among those who could be vulnerable to infection.

Mpox is transmitted through direct contact between skin and the lesions or biological fluids of an infected person, especially during sexual activity.

Symptoms include a fever, headache, fatigue, chills, and muscle aches, followed by skin rashes that can be very painful. The incubation period is usually five to seven days, but can last up to 21 days.

The contagious period begins when symptoms appear and ends when the skin lesions have completely healed.

Mpox usually goes away on its own within one month of infection, though some complications have been reported.