All five recent cases of the mumps virus in Guelph involved students who had received their vaccinations for measles, mumps and rubella, public health officials say.
Five cases of mumps have been reported to Wellington-Dufferin-Guelph Public Health in recent weeks.
Each case involved students at either Bishop Macdonell Catholic High School or Our Lady of Lourdes Catholic School.
The city’s public officer of health says vaccination remains the best way to prevent mumps – even if it wasn’t enough in these cases.
“It is possible that there are a few individuals who either did not develop immunity to disease, or that immunity has declined over time,” Dr. Nicole Mercer said Wednesday.
Specifically, Mercer pointed to the thousands of students at the schools who were not infected – most of whom, she said, had been vaccinated.
Typically, mumps is spread through droplets of saliva.
While it can be spread through something as simple as a sneeze, transmission more commonly occurs through actions like sharing water bottles or kissing.
The working theory in this case is that the outbreak originated with a sibling or close friend of one of the known patients, who likely didn’t display symptoms of the disease.
Further cases of mumps aren’t expected, Mercer said – although given the incubation period hasn’t passed, it’s impossible to be certain of that.
These five cases represent the first confirmed mumps cases in Guelph since 2010.