Evidently,the cases of leprosy that were reported on Thursday were not new cases but have been tracked over the last 2 to 3 years. And there isn’t a worry about an epidemic because only 5% of the population are susceptible to the disease:

The Arkansas Department of Health in Little Rock says some Northwest Arkansas doctors have wrong information that’s leading them to fears of leprosy cases.
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Thursday, Springdale Doctor Jennifer Bingham told 5News there were nine cases of leprosy in the Springdale Marshallese population.
Those cases are not new. In fact, the health department has been tracking them for the last two to three years.
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“The conception is that it’s a very contagious disorder, but that turns out not to be true. And then as we learn more about the genetics involved, we understand that only a small percentage, only 5% of the population are susceptible,” says Phillips.
Dr. Phillips says the latest medical information shows only five percent of the population is suceptible to leprosy, which is typically spread through close contact with mucous or other bodily fluids, over a long period of time.