Such hidden outbreaks may contribute to the substantial burden of apparently sporadic Campylobacter from cattle where transmission routes are not certain.
Critics have accused the Thai government of trying to hide the outbreak by blaming the deaths of tens of thousands of chickens since November on poultry cholera.
Government officials hid the outbreak for four months, even concealing patients at closed military hospitals, before the disease spread to Hong Kong and then around the world.
Without enforcement powers, the agency can do little to stop a country from trying to hide an outbreak that it finds embarrassing -- until it's spread so much that it's no longer a secret.
Third, and very important, countries that used to hide their outbreaks now admit them.
The Chinese authorities tried to conceal the outbreak, hiding sick patients from the World Health Organization, whose members were barred for five weeks from visiting Guangdong Province, the outbreak's epicenter.
In the case of purely geographic surveillance, sudden highly localized outbreaks may be hidden in the data that have been aggregated for a region, whereas such events are more likely to be revealed once a temporal dimension has been incorporated.
Many governments have, since the 1997 bird flu outbreak in Hong Kong, either hidden their cases or failed to provide virus samples and detailed human case information to the World Health Organization or its veterinary counterparts in a timely fashion.
And the VA placed Terry Wolf, the director of the Pittsburgh VA, on paid leave in June after an internal review of a deadly Legionnaire's disease outbreak that was initially hidden from the public and press.
Without this, poor farmers will be tempted to hide bird-flu outbreaks and continue to sell poultry that should be culled.
