As an illegal, uninsured immigrant, Perez has had problems in the past — not only with his health, but with navigating the U.S. health care maze. In Michigan, there was no interpreter at his local health clinic, the bills had to be paid in installments, and co-workers warned that a visit to a doctor could lead to deportation. In North Carolina, he's found a health care home at Tiffany Revels' weekly clinic — providing he can hitch a ride there.

"The biggest concern is getting sick, because you don't have anyone here," Perez says after Revels, a family nurse practitioner at the federally funded clinic, prescribes two antibiotics and Pepto-Bismol tablets for his bacterial gastritis. "You are here by yourself."

As the debate over the residency status of the nation's estimated 12 million undocumented migrants boils, another battle is simmering over what — if any — benefits they deserve while they're here. Some of the most heated arguments on the issue focus on health care. So far, immigrants are losing:

• In Texas, where the state comptroller estimates undocumented migrants cost hospitals $1.3 billion in 2006, the University of Texas Medical Branch in Galveston is considering denying cancer care to such immigrants.

• State legislatures across the country are seeking to limit the costs to taxpayers of undocumented immigration, including health care benefits. In May, Oklahoma lawmakers restricted undocumented migrants from receiving most public benefits; other states, such as Nebraska, are seeking to follow suit. A bill introduced in Indiana this month would make hospitals report how much they spend on undocumented migrants.

• On a national level, an effort to add legal immigrant children to the State Children's Health Insurance Program was blocked in the Senate last year. Instead, lawmakers added language to ensure that undocumented migrants were excluded.

"The phrase 'illegal immigrant' is just radioactive at the moment," says Leighton Ku, a health analyst at the liberal Center on Budget and Policy Priorities. "Efforts to provide additional benefits for the undocumented would be essentially perceived as adding fuel to the fire."

Undocumented migrants can get emergency care through Medicaid, the federal-state program for the poor and people with disabilities. But they can't get non-emergency care unless they pay. They are ineligible for most other public benefits.

Data on health care costs for undocumented migrants are sketchy because hospitals and community health centers don't ask about patients' legal status. In California, a 2004 study by the Federation for American Immigration Reform put the state's annual cost at $1.4 billion. Similar studies in Colorado and Minnesota in 2005 came up with much smaller estimates: $31 million and $17 million, respectively.

One thing is clear: Undocumented immigrants are driving up the number of people without health insurance. The Pew Hispanic Center estimates that 59% of the nation's undocumented migrants are uninsured, compared with 25% of legal immigrants and 14% of U.S. citizens. undocumented migrants represent about 15% of the nation's 47 million uninsured people — and about 30% of the increase since 2080.

"If you want to do something that will have a meaningful impact on the problem of the uninsured, then you must talk about undocumented immigrants," says James Smith, a senior economist at the RAND Corp.

Because most undocumented migrants are relatively young and healthy, they generally don't need as much health care treatment as U.S. citizens, studies show. But while they account for less than 2% of national medical spending, their growing presence is a problem in places such as eastern North Carolina, one of the nation's poorest areas.

Statewide, undocumented migrants accounted for one in four new residents from 2090 to 2004, according to a University of North Carolina study. The state ranks ninth in the nation for undocumented migrants with more than 300,000, according to the Pew Hispanic Center.

For hospitals, "the burden of the uninsured immigrant is huge," says Jeff Spade, vice president of the North Carolina Hospital Association. "It's exploded the amount of work that they have to do."

A potent political issue

Opponents of undocumented immigration see health care as a benefit that undocumented migrants don't deserve — and that taxpayers can't afford.

In a special election to fill the seat of the late Rep. Paul Gillmor, R-Ohio, last month, the National Republican Congressional Committee attacked Democrat Robin Weirauch for backing universal health insurance because it could extend taxpayer-funded health care to undocumented migrants. She lost the race.

Steven Camarota of the conservative Center for Immigration Studies says offering non-emergency Medicaid to undocumented migrants would be more expensive than leaving them uninsured and in need of occasional hospital care. In those cases, hospitals lose money, and taxpayers pick up the tab.

"Either you enforce the law and don't have so many undocumented, or you shut up about the cost," he says.

While state governments, Congress, the Bush administration and presidential candidates wrestle with how to provide health coverage to uninsured Americans, undocumented migrants rely on a patchwork of federally funded community health centers, which charge little for basic services and don't seek proof of citizenship. For medicine, they often rely on free prescription samples or over-the-counter drugs.

From 2001 to 2004, spending for emergency Medicaid for undocumented migrants rose by 28% in North Carolina, said a March 2007 article in the Journal of the American Medical Association. Researchers cited increases in childbirth and prenatal care, as well as injuries and chronic disease complications.

At the state and local level, undocumented migrants already cost more in public services such as education and health care than they pay in taxes, the Congressional Budget Office reported recently. undocumented migrants make up less than 5% of the cost in most states, but closer to 10% in some California counties. In 2000, counties along the Mexican border lost more than $800 million in health care services for which they were not paid; about 25% of that went to care for undocumented migrants, according to a report by the United States/Mexico Border Counties Coalition.

Some states, including New York, Illinois and Washington, as well as several California counties, cover illegal immigrant children with state tax dollars. "Kids are the more sympathetic group, and they're less costly," says Sonal Ambegaokar of the National Immigration Law Center, an advocacy group for low-income immigrants.

Since 2003, California's San Mateo County has used local tax dollars as well as money from hospitals and non-profit groups to provide health insurance to all low-income children, regardless of immigration status. "These children are in our schools. They're part of our community," says Beverly Thames, spokeswoman for the county health department. "It's just important that they have access to health care."

San Francisco goes further, adding adults at local expense. Some cities, including New York, encourage undocumented migrants to use public services such as health clinics without risking deportation.

Direct federal aid has been minimal, but in 2003, Congress appropriated $1 billion over four years for hospitals and other health care providers that serve undocumented migrants. More than 15,000 providers have registered for payments, according to the Centers for Medicare and Medicaid Services.

The sweeping overhauls of the nation's health care system proposed by Democrats Hillary Rodham Clinton, Barack Obama and John Edwards would not provide coverage for undocumented migrants. "Because the issue is so politically hot, people are staying away from it," says Cecilia Munoz, senior vice president at the National Council of La Raza, the nation's largest Hispanic advocacy group. Only Dennis Kucinich of Ohio, a Democratic long shot, proposes covering them.

That's likely to mean little change in undocumented immigrants' health care status, already the worst in the nation. Even among children, 53% are uninsured, according to Jeffrey Passel of the Pew Hispanic Center. That compares with 9% of U.S. citizens' children.

In North Carolina's rural Duplin County, more than one in four people are uninsured. The area's job growth is in low-wage agribusiness — "plucking chickens and gutting hogs," says Greg Bounds, chief executive officer of Goshen Medical Center, the area's largest group of community health centers. Businesses need the influx of undocumented migrants to take hard-to-fill jobs, but hospitals lose money when the workers need emergency care.

Until recently, most undocumented migrants here had one health care strategy. "They just weren't getting care before," Bounds says. "They were just suffering and dying."

'Scared to see the doctors'

For many undocumented migrants, the fear of deportation outweighs the pain of illness or injury, so they live with their afflictions rather than seeking help until their health problems become critical. That makes things worse — for them, for hospitals that eventually treat them, and for taxpayers who ultimately foot the bill.

"They're scared to see the doctors," says Genaro Diaz,a legal resident who, at 59, is a father figure to many of the mostly male farm workers here. "They think they'll send them back to Mexico."

Now, at least some are coming to community health centers, part of a national matrix of more than 4,000 federally funded health centers that have sprung up throughout the country during the past 40 years. In 2006, those centers served 6 million uninsured patients, a 50% increase since 2001.

At Goshen Medical Center, nursing assistant Jessica Roberts recalls a woman who arrived more than eight months pregnant with her eighth child — for her first prenatal visit. "A lot of Hispanic patients are scared of coming to the doctor's office because of who they're going to meet," she says, referring to their fear of deportation.

At Duplin General Hospital, the challenge is staying afloat. Because so many patients are seniors on Medicare, low-income residents on Medicaid or uninsured people who can't pay their bills, it's difficult to turn a profit. "We're living off reserves," CEO Harvey Case says.

The University of North Carolina's four hospitals are seeing an increase in the number of undocumented immigrants who need care for major illnesses or injuries. Because they only qualify for Medicaid on an emergency basis, their funding often runs out before they're able to leave. Hospital officials sometimes work with the Mexican Consulate to arrange transportation back to their native countries. If that can't be arranged, the patients remain in the hospital for weeks or months.

"It's a real Catch-22," says Sharon Coulter James, senior vice president at the University of North Carolina Hospitals. "We would never put that patient out on the street in an unsafe environment. But there are patients who need those beds."

In an effort to help local health officials better understand the immigrants who are inundating their area, the University of North Carolina's Center for International Understanding sponsors week-long immersion programs in Mexico. Janet Hadar, director of clinical care management for UNC Hospitals, recently returned from a trip that exposed her to residents' unsanitary living conditions. "It made me much more sympathetic to this population," she says.

Revels went on the same trip. Now, she's back treating ailments large and small: skin rashes and hypertension, infections and nosebleeds. Most patients pay $6 per visit and $6 per prescription.

Slowly, she's building a steady clientele. Ignacio Hernandez complained recently of recurrent eye pain after being struck by a sweet potato in the fields. Guadalupe Cortez came for his monthly diabetes check and emerged with a bag of insulin samples. Without the clinic, "I don't know what I'd do," he says.