'Patient zero' of Michigan measles outbreak thought he was immune because he had it before: Doctor There have been 20 confirmed cases in the state.

The man who is believed to have brought the ongoing measles outbreak to Michigan thought he was immune to the disease, according to a doctor who spoke with him.

The man, who remains unidentified but is believed to be "patient zero" in Michigan, traveled to the Great Lake state from New York in March.

The man had previously traveled to the U.S. from Israel in November, making it unlikely that he was infected then, and more likely that he caught the disease while in New York, according to Steve McGraw, the emergency medical services director for Oakland County, Michigan, who spoke to him days after he was diagnosed.

It is not clear if the man is a U.S. citizen.

There have been hundreds of confirmed cases of measles in New York since an outbreak started there in 2018, and has continued into 2019.

During the roughly 15-hour drive from New York to Michigan, the man felt fine, but "he got sick when he arrived, started having a fever, cough and headache," McGraw said. He added that in early March, it isn’t uncommon for people in Michigan to have those symptoms.

After seeking a doctor’s opinion, the man was misdiagnosed with bronchitis, but according to McGraw, the man returned the next day. That's when the doctor became concerned when he saw a rash on the man’s face.

The doctor "did a heroic thing and he called the health department," McGraw said. Officials then had trouble finding the man with measles because he "did not have a reliable cell phone" and "wasn’t really on any particular itinerary."

McGraw said that the patient was fundraising on behalf of Orthodox Jewish charities and "he would be in, sometimes, three different synagogues in a day."

Once it was determined where the man was, McGraw, who is also the medical director of the Detroit-area Hatzalah, which is an emergency medical service for Orthodox Jews, met with him. After communicating with him through a translator -- because the man does not read or speak English -- McGraw was able to tell him that "this was definitely measles."

"He was really upset," McGraw said. "He really had no idea he had been sick that way, especially that he had been contagious."

The outbreak in Michigan’s Oakland County started in mid-March, and 39 cases have been confirmed since then. There have also been three other individual measles cases in three other counties.

Michigan is one of 20 states where there have been confirmed cases of measles this year. According to the Centers for Disease Control and Prevention, there have been 555 confirmed cases nationwide.

Many of those connected to the outbreaks have ties to communities with low vaccination rates, and Orthodox Jewish communities in New York have been impacted extensively.

McGraw said that the Orthodox Jewish community in Oakland County was very receptive to treating the measles outbreak and having individuals get vaccinated. Rabbis worked with local synagogues to open vaccination clinics, leading to "hundreds and hundreds of people waiting in line just to get their vaccination," McGraw said.

The individual who brought the disease to Michigan suffered from what McGraw said is a common misconception -- the man, who is in his 40s or 50s, believed that he was immune from the disease because he said he had it when it was younger.

"He was told he was immune because he had the measles [when he was younger], that’s why initially he completely discounted his [the doctor’s] suggestion," McGraw said.

"I know people who believed they were fully immune because they had measles, and then they had measles in the past month and a half," McGraw said, referring to other cases.

The timing and widespread roll out of the measles vaccine can also play a role in whether or not someone has full immunity. Prior to 1989, doctors typically only issued one vaccination, but after that date, two vaccinations for measles became standard. One immunization is 93 percent effective while two are 97 percent effective, according to the CDC.

McGraw’s advice is to get another immunization if there is any question as to whether or not you had two doses.

"Nothing is as good as certainty. Unless you know you’ve had two, just get a second one," McGraw said.

The CDC considers anyone who had two doses as a child as protected for life from the disease, and said that adults only need one dose, but there are cases where a second adult dose would be helpful.

"Adults who are going to be in a setting that poses a high risk for measles transmission should make sure they have had two doses separated by at least 28 days,” the CDC’s website reads. “These adults include students at post-high school education institutions, healthcare personnel, and international travelers."