"Sick individuals are being treated by skilled doctors and are receiving the best care available," Trotter said in a statement.
The MTC, which houses thousands of missionaries while they learn languages and teaching skills before being sent out across the globe, has been proactive in stopping the virus' spread since cases began multiplying around New Year's Eve, Trotter said. MTC officials are encouraging such practices as good hygiene, hand washing and limiting contact with others. Missionaries won't be allowed to leave for their missions until they are recovered.
Utah County Health Department spokesman Lance Madigan said health officials are doing tests to learn exactly what is afflicting the missionaries, but they are almost certain it's norovirus, a highly contagious bug that quickly causes diarrhea, vomiting, nausea and fever. Lab tests will confirm the source of the outbreak within the next few days.
"We don't have confirmation, but it's got all the classic symptoms," Madigan said.
Norovirus usually thrives in places where people are cloistered together. Cruise ships, for example, can be a norovirus incubator, and the MTC, a large campus where missionaries eat, sleep and study for weeks, is a prime environment, according to Madigan.
"It's a very contained population," Madigan said. "They, frankly, don't get out much."
The virus isn't pleasant but usually isn't life-threatening, he added.
Reports about the outbreak started coming into the health department around New Year's Eve. The most cases reported in one day were about 150 on Tuesday. Since then, the numbers have been dropping. Madigan said a little more than a dozen cases were reported Thursday. The MTC's insistence on clean hands seems to have had an effect, he said.
A few rumors about the outbreak suggested that sick missionaries had to be quarantined, but MTC Human Resources Manager Spencer Christensen said that was not the case.
"It's not bad enough to where we've had to quarantine," he said. "We have had to do that historically, but not now."