United States health officials expect to see more cases of measles this year than they have seen in nearly two decades. The worst part? The size of outbreaks within North America appears to be growing, and the year is far from over.

The US Centers for Disease Control and Prevention (CDC) officially declared the measles virus eradicated in the United States back in 2000, soon after the measles-mumps-rubella (MMR) vaccination was included as part of the Childhood Immunization Program.

This occurred after the highly contagious air-borne virus no longer had an adequate number of susceptible hosts to spread to in the US.

However, according to a recent CDC report, the number of measles outbreaks seen this year in the US makes it look as if the virus never left. As of May 9, the US has seen 187 confirmed cases of measles between outbreaks in Connecticut, New York, and particularly California. That number rose to at least 255 cases this week when Ohio reported an outbreak among its Christian and Amish communalities, which resulted in an estimated 68 cases of infection, according to a CNN report.

The CDC says that 17 US states in all have had at least one case of measles. Isolated cases are, of course, nothing to be concerned about. Even if the majority of the US is inoculated, unvaccinated citizens can still pick up the virus during international travel and bring it back to the United States. However, once here, the virus has no place to go.

The CDC and the California Department of Health expressed their concerns last March that cases of imported measles were going to be on the rise this year as countries like the Philippines and Vietnam continue to face what the World Health Organization is calling a massive measles epidemic.

However, the CDC reports that 15 outbreaks have already occurred within the United States, with several more occurring in many inoculated religious communities in Canada.

This is worrisome for US officials, who saw only 11 outbreaks in 2013, only three of which involved more than 20 people. Outbreaks including at least 68 cases tells CDC officials that it is very likely that we will see more measles cases this years than in the last 18 years.

According to the CDC, measles is deadliest to young children and pregnant women. Victims of the virus often experience dangerously high fevers and a full-body rash. The virus has also been known to cause tragic stillbirths.

Thankfully, the virus is easily avoidable with a MMR vaccination.