You wake up one morning and you're feeling achy and feverish. The directions from health officials battling swine flu are clear: Stay home from work. Don't risk infecting others. And certainly don't send a sick kid to school.

But what if you're one of the estimated 57 million working Americans with no paid sick days?

Staying home could mean losing a paycheck, or worse, losing your job entirely.

The prospect of workers showing up with swine flu — or sick kids infecting their schoolmates — is bringing added urgency to efforts to pass a federal law guaranteeing paid sick leave.

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"The problem has really come into sharp relief the past few days," said Debra Ness, president of the National Partnership for Women and Families, which has long pushed for paid sick leave. "Many people don't even realize that almost half the private sector — 48 percent — has no sick days, not even a single one."

"We have officials telling people to stay home when they're sick," she added. "Well, guess what? That can be the beginning of economic disaster for many, especially in this economy."

Making matters even worse: Those least likely to have sick leave are low-income workers, particularly in fields like food services, child care and the hotel industry — in other words, the people you most want to be staying home if they're sick. "The public health implications of this are huge," Ness said.

The Associated Press interviewed a number of workers in the food industry. Not surprisingly, most didn't want their names used for fear they would be fired. They told stories of coming to work with a fever or flu in order to keep their jobs, and of seeing sick co-workers sneezing and coughing near food.

"As a student I'm working to help pay my education, so I have to keep this job," said one who agreed to be identified, Grace Fuhr, a bartender and waitress at the Bucca di Peppo restaurant in Milwaukee.

"I've had to work sick — when I was pressured to work after a car accident, and when I've had a cold," said Fuhr, 21. "Swine flu could create an epidemic in restaurants. I have co-workers who are single parents and have impossible decisions when their kids are sick."

A study on sick leave found that 68 percent of those without paid sick days had gone to work with a contagious illness like the flu or a viral infection. And one of six workers reported that they or a family member had been fired, suspended, punished or threatened with firing after taking time off to care for themselves or a family member, according to the 2008 study by the University of Chicago's National Opinion Research Center.

Making the problem even thornier: Kids. Children get sick all the time and infect each other. Yet even among those workers lucky enough to have paid sick leave, few have flexible sick days that can be used to care for a family member.

"I can't tell you how many parents face this dilemma: Do I send my kid to school with a fever or face economic ruin?" Ness said. She calculated that 100 million workers lack flexible sick days.

Advocates for family-friendly policies point out that the U.S. is the only country out of the top 20 world economic powers with no federally mandated sick days. Put another way, some 140 other countries have them.

No U.S. states have them either, though three cities have passed such measures: San Francisco, Washington and Milwaukee, where implementation has been held up by a lawsuit.

Advocates for paid sick leave are hoping the swine flu scare will give them momentum.

President Barack Obama mentioned the problem Friday, saying the administration is working with the U.S. Chamber of Commerce "to ensure that businesses are supportive of their hourly workers who need to stay home but may be worried about losing their jobs because they don't have sick leave."

And earlier this week, Sen. Edward M. Kennedy, D-Mass., and Rep. Rosa DeLauro, D-Conn., wrote colleagues seeking sponsors to reintroduce the Healthy Families Act, which would let workers earn up to seven paid sick days a year — days that could also be used to care for a family member. They didn't specify a date, but a Kennedy aide said they hope to make the move by the end of May.

"That would be good for public health and for business, too," said Kristin Rowe-Finkbeiner, co-founder of MomsRising, which lobbies on issues concerning working women and families. "Because businesses lose money when the whole place has to shut down."

She and others pointed to a 2004 study by Cornell University showing that "presenteeism" — people showing up for work sick — costs the economy $180 billion annually in lost productivity, or more than $250 per employee per year.

That's more, they said, than the cost of providing sick days.