Jeffrey D. Allred, Deseret News
The MMR vaccine in Provo Wednesday, Jan. 7, 2015.

SIOUX FALLS, S.D. — An unvaccinated child has been diagnosed with the measles in Sioux Falls, state and local health officials said Saturday, meaning 14 people have now been diagnosed in the last month with the highly contagious disease in South Dakota.

The child is under age 10 and lives in Sioux Falls, but no other personal information was released. Health officials did say the child was at Holy Spirit Elementary School in Sioux Falls on Thursday, and they urged any unvaccinated individuals who also were at the school that day to get vaccinated by Sunday.

Health officials said the latest case appears to be unrelated to the outbreak that involved 13 people so far in the Mitchell area, about 70 miles west of Sioux Falls. The child has not traveled to Mitchell since the outbreak began there in late December, but it's unclear if any individuals infected with the virus in Mitchell have traveled to Sioux Falls, authorities said.

Measles is a viral disease that can cause permanent brain damage or even death. It is spread by direct contact with nasal or throat secretions of infected people, or by airborne transmission. Before the Mitchell outbreak, the state had not seen measles cases since 1997.

"The viral particles can persist in the air two hours after the contagious person has left the room or the airspace," said state epidemiologist Lon Kightlinger. "It's a very serious disease."

In response to the latest case, officials urged anyone who isn't vaccinated against the virus to attend a free measles vaccination clinic that was scheduled for Saturday. Kightlinger said any unvaccinated individuals who attended the school Thursday have a 72-hour window, which ends Sunday, to receive the vaccine to prevent becoming ill.

All people involved in South Dakota's outbreak had not gotten the measles-mumps-rubella, or MMR, vaccine. The U.S. government in 2000 declared that measles had been eliminated, but the country experienced a record number of cases in 2014. The virus can still enter the country from abroad where it's still a problem.

An outbreak of measles that originated at Disneyland last month reportedly has sickened at least six dozen people — most of them unvaccinated — in several states and Mexico. Kightlinger said the latest South Dakota case is not related to the theme-park outbreak.

South Dakota's vaccination rates are higher than the national average. Kightlinger said 93 percent of children in the 2-year-old range are vaccinated against measles. That statistic goes up to 97 percent for kindergarteners and 94 percent for teenagers, as the vaccine is required for school admission.