It took just one two-year old to spark a statewide measles outbreak.

One unvaccinated two-year old.

A study in the online journal Pediatrics has shown how just one small child sparked a massive contamination.

The outbreak in 2011 infected 19 children and two adults and exposed 3000 people to the disease in the state of Minnesota in the US.

It offers a case study of how the disease is transmitted throughout the world – the report shows how an unvaccinated person travels overseas, brings measles back and infects vulnerable people — including children who are unprotected because their parents chose not to vaccinate them.

The Minnesota outbreak began when an unvaccinated 2-year-old was taken to Kenya, where he contracted the measles virus. After returning to the United States, the child developed a fever, cough and vomiting. However, before measles was diagnosed, he passed the virus on to three children in a drop-in childcare center and another household member.

Contacts then multiplied, with more than 3,000 people eventually exposed.

And tellingly nine of the children ultimately infected were old enough to have received the measles-mumps-rubella (MMR) vaccine but none of them had.

Of great concern is the fact that according to the report in most of those cases, the child’s parents feared the MMR vaccine could cause autism.

Pam Gahr, an epidemiologist wrote in the journal, Pediatrics  “I think that as long as autism remains unexplained, the idea that the MMR is a cause will persist.”

A recent study led by the University of Sydney showed beyond a shadow of a doubt that there is no link between autism and vaccines.

Previously Dr Rachel Dunlop wrote for Mamamia:

“There is no solid scientific evidence for a link between vaccines and autism. And believe me, science has been looking for well over 14 years. The theory that vaccines cause autism was first suggested by Andrew Wakefield in 1998.

Since then, Wakefield’s paper has been discredited and withdrawn from The Lancet and Wakefield has lost his medical licence for showing “callous disregard” for children’s welfare. Since 1998 there have been countless large and comprehensive studies looking for a link between vaccines and autism, but the evidence keeps coming up negative”

Despite the unique circumstances of the Minnesota outbreak, though, measles can happen anywhere people are unvaccinated.

Dr. Andrew Pavia, chief of pediatric infectious diseases at the University of Utah in Salt Lake City told CBS News. “These outbreaks occur in all types of settings.”

In the U.S. measles cases are at a 20-year high this year, the U.S. Centers for Disease Control and Prevention reported last week. As of May 30, the agency had received reports of 334 measles cases in 18 states.

Nearly all of the outbreaks involved unvaccinated people who brought measles back after a trip overseas, the CDC said.

The hardest-hit state is Ohio, where people in several Amish communities were infected after unvaccinated missionaries traveled to the Philippines and carried the measles virus back. Amish communities have historically had low vaccination rates – a 2011 survey of Amish parents who refused to vaccinate found that nearly all cited safety fears according to CBS News.

In Australia just recently there have been five cases of measles reported in NSW. Two were associated with travel to Vietnam, one to Indonesia and one to the Philippines.

In Australia, 41 per cent of cases of measles in 2014 have been imported from overseas, mostly from the Philippines.

According to Dr Pavia, the safety concerns of parents in the Minnesota outbreak illustrate the “power of bad information.”

The MMR-autism link proposed by Wakefield was later found to be based on fraudulent data, and many studies since have found no connection between the vaccine and autism.

“Wakefield has been thoroughly debunked,” Pavia said.

For some parents though the symptoms of measles may not be easily recognised, and they may not realise how dangerous the disease can be.

NSW Health director of communicable diseases Vicky Sheppeard told News Limited recently that measles is highly contagious among people who are not fully immunised. “Measles is spread through coughing and sneezing, and is one of the most contagious infections known,” Dr Sheppeard said.

About 30 percent of people with measles develop a complication such as ear infection, diarrhea or pneumonia. Among children, one in 1,000 suffers brain inflammation, and one or two out of every 1,000 die.

Measles typically begins with a fever, cough, runny nose and “pink eye.” After several days, a rash emerges around the face and neck, then spreads to the rest of the body.

“The thing is, we have the power to prevent it,” Dr. Andrew Pavia said.

In the case of the Minnesota outbreak, “the first infection that spread in the community was misinformation.” he said.

“The second was measles.”

 Vaccinations:

Measles vaccination is recommended as part of routine childhood immunisation.

It is listed on the National Immunisation Program (NIP) Schedule and funded for children under the Immunise Australia Program.

To receive measles immunisation, visit your local doctor or immunisation provider. Immunisation against measles is achieved using the MMR and MMRV combination vaccines.

The first dose is given at 12 months of age as the MMR vaccine and the second dose is given at 18 months of age as the MMRV vaccine.

If your child is aged over 18 months at 1 July 2013, they will receive the second dose at four years of age as the MMR vaccine, as per the previous NIP schedule.

This schedule point will remain until 31 December 2015.Babies who are travelling before their vaccines are due can be given the first dose as early as nine months of age.