Jim Gathany / CDC

In an attempt to avoid a chicken cull, Thai farmers are buying bird vaccines on the black market. The government is now considering whether to allow use of the avian-influenza vaccines, which were banned because of safety concerns. A government committee weighing up the issue is expected to report within the next few weeks.

This follows a government crackdown on their use. Vaccination claims to keep healthy birds infection-free, protecting the livelihoods of farmers and avoiding the need to kill hundreds of thousands of birds. But experts at the United Nations Food and Agriculture Organization warn that even seemingly healthy vaccinated birds can contract the virus and spread it, and that black-market vaccines themselves might aid development of a more dangerous strain.

Experts agree that vaccine use can be successful, as long as it is accompanied by strict monitoring and testing — something Thailand does not have the resources to do. Culling remains by far the most effective way to stop avian influenza spreading, but this could have a massive impact on the country, once one of the world's main poultry exporters. While the government considers its next move, it plans an educational campaign. But this is not expected to end the use of illegal vaccines.

Read more about bird flu in SciDev.Net's bird flu news focus.