From a Few Cases to Thousands - The Role of Patient Zero in Recent Measles Outbreaks
The Real Truth About Measles
If you or your child is intentionally unvaccinated, you should understand that in addition to the risk that you will get sick with a vaccine preventable disease like measles, there is the very real risk that you can trigger an outbreak. From a few cases to thousands, that is tragically what we have been seeing with recent, record-breaking measles outbreaks.
From a Few Cases to Thousands - The Role of Patient Zero in Recent Measles Outbreaks
Take a recent outbreak in Cairns, Australia - “the largest experienced in the city in nearly three decades.”
“The outbreak was traced back to a tourist arriving from Indonesia.”
How a sole tourist sparked Cairns’ worst measles outbreak in nearly 30 years
Altogether, in this outbreak in Cairns:
nearly a dozen people got sick with measles
at least 1,481 people were exposed and notified as potential contacts
there were at least 48 potential exposure sites, including various wards at Cairns Hospital where they were taking care of high risk patients.
And it was all traced to a single person.
This tracks with most other recent measles outbreaks, including the :
New Mexico Outbreak - an unvaccinated school-aged child in Lea County was the first known measles case in a 2025 outbreak that spread to 99 other people and led to one death. The outbreak had spread from a larger measles outbreak in Texas.
Clark County Outbreak - an unvaccinated ten-year-old from Ukraine was the first known case in 2019.
Rockland County Outbreak – an unvaccinated teenager brought measles to Rockland County in September 2018 from Israel. At least 206 people got sick.
Brooklyn Outbreak – the initial case in Brooklyn was unvaccinated and got measles in October 2018 on a visit to Israel. Measles was reintroduced into the community at least six other times though, four cases were also acquired on visits to Israel, while two people got measles from the U.K., and one from Ukraine. At least 242 people got sick.
Minnesota Outbreak - an unvaccinated two-year-old was the first known measles case in an outbreak that spread to 65 other people, including kids at 5 schools and 12 child care centers.
Pacific Northwest Outbreak – a child who had traveled from Ukraine to Washington was the first confirmed case and likely source of the Pacific Northwest measles outbreak.
Michigan Outbreak - an unvaccinated man got 39 people sick after traveling to Michigan from New York during their 2018 outbreak
Ohio Outbreak - two unvaccinated Amish travelers went to the Philippines after a typhoon for mission work and returned with measles. They triggered an outbreak (but would have gotten vaccinated before the trip if they had known it was recommended!) in 2014 that led to 383 people getting sick.
Brooklyn Outbreak - an intentionally unvaccinated teenager returned from UK and triggered an outbreak in New York that got 58 people sick in 2013
Indiana Outbreak - an intentionally unvaccinated 24-year-old returned from a trip to Indonesia with measles and got 14 other people sick in 2011, including a woman who was 32 weeks pregnant.
San Diego Outbreak - was triggered by an unvaccinated 7-year-old boy who had traveled to Switzerland with his family, getting 11 other children sick in the 2008 California outbreak, including three infants too young to be vaccinated who were exposed at their pediatrician’s office.
This is the story of an infant who was too young to be vaccinated was hospitalized after they were exposed to measles at their pediatrician’s office. Indiana Outbreak - an unvaccinated teenager returned from a missionary trip to an orphanage in Romania with measles and started an outbreak that got 34 people sick in 2005.
They were each traced to a single person.
The Role of Patient Zero in Canada’s Measles Outbreak
As was a recent measles outbreak in Canada, which is linked to an unvaccinated woman traveling to her sister’s wedding in New Brunswick.
“Patient zero, as identified by the Globe and Mail newspaper, was a Canadian who was living in Thailand when measles broke out there in 2024. In October that year she attended a wedding in the province of New Brunswick where she was later admitted to hospital with severe illness and tested positive for measles.
She had never been vaccinated for measles, nor had several of the other wedding guests. From there they brought the virus to communities across Canada where vaccination rates were low. Mennonite and other Anabaptist communities were mostly affected, but experts say other communities with similarly low vaccination rates are also at risk.”
How a wedding lost the Americas its measles-free status
And then, from that wedding in New Brunswick:
at least 50 people got sick in an outbreak that lasted just over two months
an outbreak that spread to other Canadian providences, leading to the loss of its measles elimination status
up to 6,398 people got sick with measles across Canada and 2 people died
And it all started with a single person.
The Role of Patient Zero in Mexico’s Measles Outbreak
Then there is the even larger measles outbreak in Mexico.
“Mexico’s current outbreak began in March. Officials traced it to an 8-year-old unvaccinated Mennonite boy who visited relatives in Seminole, Texas — at the center of the U.S. outbreak.”
Vaccine teams in Mexico scramble over measles outbreak from Mennonite community
Another outbreak that can be traced to just one unvaccinated person - a child who visited relatives in Texas.
An unvaccinated child who triggered a large, ongoing outbreak in Mexico that has:
spread across Mexico
gotten up to 18,385 people sick with measles and led to 43 deaths
And it all started with a single person.
Bottom line - don’t be that intentionally unvaccinated person that starts an outbreak that gets other people sick with a life-threatening disease!
More on Starting a Measles Outbreak
What We Know About the Hospitalized Measles Patients in the Texas Outbreak
How a sole tourist sparked Cairns’ worst measles outbreak in nearly 30 years
Vaccine teams in Mexico scramble over measles outbreak from Mennonite community
‘Patient zero’ of Michigan measles outbreak thought he was immune because he had it before
A Measles Outbreak in an Underimmunized Amish Community in Ohio
Consequences of Undervaccination — Measles Outbreak, New York City, 2018–2019
Outbreak of Measles --- San Diego, California, January--February 2008
Import-Associated Measles Outbreak --- Indiana, May--June 2005