Bird Flu Has Been Bad News For KFC China's Chicken Sales

But lately, KFC's China sales have struggled due to concerns over the avian flu.

In a new regulatory filing, parent company YUM! Brands reports that KFC March same-store sales fell 16 percent in China.

"Within the past week, publicity associated with Avian flu in China has had a significant, negative impact on KFC sales," said management. "Historically in these situations, we have educated consumers that properly cooked chicken is perfectly safe to eat, and we will continue to do so. We do not anticipate providing any further updates regarding China Division same-store sales until our scheduled first-quarter earnings release on April 23, 2013."

The company expects to release April same-store sales on May 10.