Officials say the cases in the county involve four family members who were exposed to another confirmed case involving someone who traveled from out of state.
On Tuesday afternoon, health officials announced the fourth case involves a woman in the same family who is between 20 and 30 years old, and is now hospitalized.
The video above is from a previous report.
According to the health department, none of the people who were infected had been vaccinated. Health officials said measles is highly contagious and can be life-threatening, especially in children younger than 5 years old.
Officials said the virus spreads through the air when an infected person coughs or sneezes.
Some of the symptoms include a fever over 101 F, cough, runny nose, red, watery eyes, and a rash, and can appear seven to 14 days after contact with the virus.