(CNN) -- While health officials have serious concerns about the H5N1 bird flu virus becoming a pandemic, they say it won't be a worldwide threat until the virus is able to spread easily between people.That has not happened yet, and scientists stress that it might not happen with this strain.Three things have to happen for a pandemic to start, according to the World Health Organization.First, there has to be a new substrain of the flu virus. Second, it has to spread to humans and cause serious illness. Finally, it has to spread easily between people.The flu virus currently circulating in Asia and parts of Europe has made the first two steps. But so far only 130 people have been infected with the H5N1 flu virus in Asia over the past two years -- 67 have died, according to the WHO.There is no bird flu pandemic anywhere in the world. Health officials say that's because, at this point, the virus does not spread easily between people.Almost all of the human cases have involved people who had direct contact with infected birds.The fear is that the H5N1 virus will change and develop into a new strain that is highly contagious among humans.Health and Human Services Secretary Mike Leavitt has told CNN that there was no way to know if this bird flu would lead to a pandemic, but said it was only a matter of time before some strain of flu virus did.He said that such an outbreak would be a natural disaster of unique proportions."It can happen in 5,000 different communities around the world at the same time. No central place can manage all of those difficulties and so local communities need to be ready, and part of the president's plan is to assure that they are," Leavitt said.Three influenza pandemics swept the globe in the 20th century. The worst, in 1918-19, killed 20 million to 50 million people, according to the Centers for Disease Control and Prevention, and triggered an international panic.The CDC has set up quarantine stations at 18 U.S. airports to monitor and respond to potential outbreaks.President Bush outlined a $7.1 billion plan to prepare for a potential pandemic in a November 1 speech.Much of the money would be spent on a stockpile of vaccine and antiviral drugs, but about $583 million is being spent on domestic preparedness and $251 million would go to help other countries detect and contain a potential outbreak."The most effective way to protect the American population is to contain an outbreak beyond the borders of the United States. While we work to prevent a pandemic from reaching our shores, we recognize that slowing or limiting the spread of the outbreak is a more realistic outcome and can save many lives," according to the Department of Homeland Security's national strategy plan.The federal plan calls for coordination with international organizations such as the World Health Organization and the Food and Agriculture Organization to isolate outbreaks.Health officials stress that there is no risk of catching the bird flu by handling or eating birds in the United States.The H5N1 virus has not shown up in the United States.If a bird were to be infected with the virus, cooking it to a temperature above 158 degrees Fahrenheit will kill the virus, according to the WHO."To date, no evidence indicates that any person has become infected with the H5N1 virus following the consumption of properly cooked poultry or poultry products, even in cases where the food item contained the virus prior to cooking," according to the World Health Organization.