“The high risk factors for this outbreak are people who inject drugs and the vast majority of those who have been found are homeless,” Dr. Smelser said.

Because of that, doctors believe that means the numbers are likely higher. It also makes the virus much more difficult to control.

“Part of that reason is, these populations are difficult to get vaccinated, as well as the virus can be shed before you have symptoms and so you can spread it before you even know you're ill,” Dr. Smelser said.

While most people will typically feel sick for a few weeks and recover without liver damage, those who are older or with other underlying illnesses can get very sick.

“In fact, all 13 of our cases were hospitalized,” Dr. Smelser said.

That's why harm reduction teams are out in full force right now, visiting homeless shelters and immunizing.

“And the City of Albuquerque has even put hand washing stations out in areas where homeless people are known to congregate,” Dr. Smelser said.

They are hoping to stop the spread of hepatitis A before the virus gets out of hand.

“We don't have an exact prediction, however in other states and areas that have had similar outbreaks, some of these outbreaks have gone on for quite some time,” Dr. Smelser said.