According to the latest estimates a bird flu pandemic could cost the U.S. economy between $500 billion and $675 billion, and cause a serious recession.

Two reports make the assumption that the H5N1 avian influenza now destroying flocks of poultry across Asia and parts of Europe will make the jump into humans and causes serious disease.

To date the H5N1 virus has killed 70 people and infected as many as 135, however world health experts predict it is very close to mutating into a form that easily passes among people.

According to both reports if this does happen it would likely be on the scale of the 1918 pandemic strain of flu that killed anywhere between 20 million and 100 million people during World War I, both reports say.

The Congressional Budget Office says this means 30 percent of the population would be infected and more than 2 percent would die.

The CBO report also assumes that those who survive would miss three weeks of work, either because they were sick, because they feared the risk of infection at work, or because they needed to care of family or friends.

Many businesses would probably suffer from a falloff in demand because people would be afraid to patronize them or because the authorities would close them.

The CBO also predicts that doctor’s offices and hospitals would be overcrowded.

Their report says that currently, the United States has approximately 970,000 staffed hospital beds and 100,000 ventilators, with three-quarters of them in use on any given day.

As a result says the report, shortages could occur in critical areas such as ventilators, critical care beds, and drugs to treat secondary infections.

The CBO also fears that hospitals would have difficulty controlling infection and might become sources for spreading the illness, a fear echoed by another group, the National Center for Policy Analysis.

The second report from New Jersey based WBB Securities LLC estimates that 35 percent of the population would become ill and 5 percent would die, and there would be a one-year economic loss of $488 billion and a permanent economic loss of $1.4 trillion to the U.S. economy.

The WBB report says if bird flu affects humans at the same level of virulence as the current H5N1 strain, almost all patients would require hospitalization, which would result in a shortage of some 6.5 million hospital beds per day during the pandemic.

It also adds that police, fire, sanitation and other critical service providers will be strained with short staff and overtime work, which would impact on municipal and state budgets.

The report also warns of the possibility of civil disturbances caused by people who either believe they can take advantage of the situation or who feel they have little chance of survival so they may as well enjoy themselves while they can.

The reports support other predictions that have been made about the potential effect on the U.S. economy, the World Bank has predicted a pandemic could cost the global economy $800 billion a year.

U.S. President George W. Bush released a $7.1 billion bird flu plan in November but Congress has yet to fund it.

Senate Majority Leader Bill Frist said he hopes for legislation before the recess this month, but many conservatives are afraid the deficit is already too big and want to make cuts to pay for the spending.

A large part of the plan involves stockpiling influenza drugs, which would not provide a cure but which might help make the most vulnerable patients less ill.