From Medical News Today (link):
China, Indonesia and Africa have more bird flu cases than are actually being reported, says Dr Christianne Bruschke, World Organisation for Animal Health Avian Influenza Coordinator. The main reason is that compensation for lost chickens is very low.
…… The problem in China, said Bruschke, is a combination of its sheer size and a poor compensation scheme. However, she stressed China is openly communicating and cooperating with the World Organisation for Animal Health and other international agencies.
See also NYTimes’ “Some Countries Lack Resources to Fully Track Bird Flu Cases” by Elisabeth Rosenthal (link)