(Photo by Centers for Disease Control and Prevention)

An illustration of a spherical-shaped, measles virus particle.

For the past several weeks, nearly two dozen cases of measles have been identified. The cases stemmed from U.S. Immigration and Customs Enforcement employees who refused to be vaccinated or show proof of vaccination.

As KJZZ first reported earlier this month, health officials believed an 8-month-old child was exposed to the virus and the family refused testing. So what happens when a person doesn’t want to be tested for a contagious and potentially deadly disease? It depends.

"So there’s certain diseases like smallpox where we can actually require vaccination because it can be so contagious and so lethal," said Jessica Rigler with the Arizona Department of Health.  "A lot of the authorities that we have, though, allow public health to exclude people, isolate them or quarantine them."

She said measles is one disease where DHS is limited in its authority. While it can quarantine a person, it can’t make them get tested or vaccinated.