Health officials said a person diagnosed with the disease over the weekend exposed passengers on Air China/Air Canada Flight CA 991/AC 6601, which arrived at Vancouver's airport on Saturday.
The first flight this year that brought measles to Vancouver from China arrived on March 21.
The newest case was contracted on that flight by the person who then returned to China before flying back to Vancouver on April 4, exposing a planeload of people to the disease, said medical health officer Reka Gustafson.
"We have nine cases in total, all related to that (first) flight," she said Wednesday.
There were 300 people on the March flight, but Gustafson said her office couldn't determine how many people were on the later flight.
Passengers from the April 4 flight are being advised to watch for symptoms such as fever, cough, runny nose, pink eye and a red rash, until April 25.
Gustafson urged people to check their immunization history, advising those born after 1970 to ensure they've had two doses of the vaccine.
She said people who were unsure about whether they were fully immunized should get vaccinated.
The measles, mumps and rubella vaccine is available from family doctors, public health units and walk-in clinics.
Most people in B.C. have received the MMR vaccine, but the health authority said some young adults and people born outside Canada may not be completely immunized against measles.
The incubation period for measles lasts from seven to 21 days, with the average being two weeks, Gustafson said.
She said the latest case was discovered early in its gestation, with fewer symptoms.
"I'm hoping that with early intervention, we will have fewer transmissions."
China has had an increase in measles cases this year, despite being a highly vaccinated population, Gustafson said.
She said the increase was another indicator of the infectious nature of measles.
"A single individual with the disease can infect up to 15 to 18 people," she said.
Gustafson ruled out screening travellers coming to Canada for measles, saying that would likely be ineffective.
She said the number of measles importations is about the same as it was at this time last year.
"It's important to keep in mind that we've seen outbreaks of measles in the United States and elsewhere in Canada."
Gustafson said that in 2014, there were 14 cases of measles reported in Metro Vancouver, most of those were imported to the province.
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