The Shanghai outbreak of H7N9 bird flu has expanded to 38 cases and 10 deaths. As poultry markets remain shuttered, international chicken giant Kentucky Fried Chicken (KFC) has seen sales drop some 13 percent in Chinese stores that have been open more than a year.

KFC parent company, Yum Brands Inc., had been enjoying 11 years of continuous growth until an incident earlier this year threatened its reputation among Chinese citizens. KFC was accused of selling chicken containing "excessive chemicals," but was eventually cleared.

Sales were picking up again until the new strain of bird flu arrived.

While Yum Inc. has mounted a public education campaign explaining that properly cooked poultry is safe to eat, whether or not Chinese citizens will be convinced, only time -- and quarterly earnings -- will tell.

Read More:

• China bird flu threatens KFC parent's winning streak (Chicago Tribune)
• KFC parent Yum says China sales hit by bird flu (CBS News)
• H7N9 Bird Flu Cases Reach 38, Deaths at 10 in China; UN Concerned (Forbes)