Parents in the De Soto School District are being warned about an outbreak of scabies.
District 73 officials sent a letter home with students Thursday notifying parents that one high school student, a junior high student, and an elementary student have been sent home with the skin condition.
Scabies is caused by tiny mites burrowing beneath the skin. It's extremely itchy and highly contagious.
District officials say they are taking steps to disinfect schools.
Students with scabies can't return to school without a doctor's note.
De Soto is about 50 miles south of St. Louis in Jefferson County.
The head of the Food and Drug Administration says writing a new menu labeling law "has gotten extremely thorny" as the agency tries to figure out who should be covered by it.
The 2010 health care law charged the FDA with requiring restaurants and other establishments that serve food to put calorie counts on menus and in vending machines. The agency issued a proposed rule in 2011, but the final rules have since been delayed as some non-restaurant establishments have lobbied hard to be exempt.
The FDA has said the rules may come out this spring, but the agency may not meet that deadline.