The CDC warned that parvovirus B19, a highly contagious respiratory illnesses that causes a ‘slapped cheek’ rash, is on the rise in the US. The disease has surged in kids and pregnant women. The CDC warned that parvovirus B19, a highly contagious respiratory illnesses that causes a ‘slapped cheek’ rash, is on the rise in the US. The disease has surged in kids and pregnant women.