Along with Washington and NY, at least seven other states - Hawaii, Oregon, Pennsylvania, Connecticut, Colorado, California and Georgia - have reported measles cases this year. Health officials have said those outbreaks are within observant Jewish communities.
The Vancouver-area measles outbreak began January 1 and stands at 49 confirmed cases and 11 suspect cases. Yale-New Haven Hospital is treating the two infected patients. One victim had had one MMR vaccine, but not a follow-up shot.
CBS News reported in October that a small but growing proportion of the youngest children in the USA have not been vaccinated against any disease.
The Bell County Public Health District said they can confirm a possible measles case in a child in Western Bell County on Monday.
Even though Arizona does not now have a reported case of measles, the state has one of the highest rates of exemptions for at least one vaccine that's required for childcare, kindergarten or sixth grade.
Experts attribute the spread of measles in part to lower vaccination rates in certain communities, making more people vulnerable to the disease and lowering the level of herd immunity that protects large groups from becoming infected.
A number of specific details about the cases in Houston have not been publicly disclosed, including how it is believed that the individuals contracted the disease and if they were previously vaccinated.
The U.S. Centers for Disease Control and Prevention attributes the rise in measles to un-vaccinated travelers who get exposed and bring it to the United States and to those who chose not to get vaccinated.
Dr. McDonald said people most at risk besides non-immunized children are those who work in the healthcare field and people who travel internationally regularly.
Measles can be spread through direct contact and as an airborne virus.
California state Sen. Richard Pan, a pediatrician who sponsored his state's bill, said he got death threats over it and had anti-vaccination advocates jam his phone lines and harass him on social media. The majority of the cases involve children under the age of ten.
It would not be unusual to see so many headlines about measles. if this were 1919. One person had one dose of the vaccine, which is 93 percent effective. One patient had received only one of the two recommended doses of the vaccine, and the vaccination status of six others was unknown, the county department of health said.
Children typically receive the first vaccine at 1 year to 15 months old, and the second dose at 4 to 6 years.
Doctors are increasingly concerned about a measles outbreak spreading across the country.