When 5 year-old Kay Bell moved to Houston, Texas, with her family in 1994, she was too young to remember details of her childhood in Nigeria, much less realize that she and her family were violating U.S. immigration law.
"I don't remember anything from before I came here," said Bell, a 21-year-old undocumented immigrant whose name has been changed to protect her identity. "Where my mom goes, my sister goes, and where the both of them go, just for peace of mind, I have to go."
Yet unlike many illegal immigrant families who migrate to the U.S. in search of better jobs, education or physical and financial security, Bell says her family came to Texas primarily seeking medical treatment for their youngest child, Bayo, who suffers from cerebral palsy.
"My parents came once to get her surgery and went back, then came once more to get a shunt in her brain, maybe when she was three or four years old," Bell said. "The last time they decided we should stay."
Bayo, who was three years old on her first trip to the U.S., underwent surgery at the Texas Medical Center to relieve dangerous pressure in her brain. After the procedure, her mother, a Nigerian medical doctor, and father, who works in the country's oil business, realized they would put Bayo at risk if they returned home.
"There's a lot of superstition in our culture, there's a big stigma and taboo around people with special needs," said Bell. "There was some tension and harassment and things going around in Lagos because of my sister's condition, which played a part in why we came here to stay."
Experts say people with mental and physical disabilities across Africa commonly confront a level of prejudice more severe than what one might face in the U.S., including physical abuse, ostracism, and fear of contagion.
"In large parts of Africa, the stigmas tie what we would call disabilities to ideas around occult power and witchcraft," said Clifton Crais, director of Emory University's Institute of African Studies. "It would be a much, much harder life and one would be living in a world in which a substantial portion of the population feared them and ostracized them and suspected them."
Fifteen years later, the Bells continue to live in the shadows in the U.S. without legal immigration status. Their case highlights the diversity of backgrounds among the country's 10.8 million illegal immigrants, including more than 200,000 from Africa.
Bell said her mother, who declined to speak with ABC News for privacy reasons, made several attempts to legitimize the family's immigration status, but at least one application was denied. The mother did obtain a temporary work visa, which has allowed her to legally hold a job and get health insurance to help cover medical costs.
Most Undocumented Immigrants Medically Uninsured
"Mom tried to have two jobs so that we'd have more than one insurance company to bounce off of when one said, 'No,'" said Bell. "But after my sister has grown older she has stabilized a lot, so now it's mostly maintenance bills and supply bills… It's paycheck to paycheck but we're still breaking even."
Bell, an undergraduate double major at the University of Texas who works for minimum wage at a hospital gift shop, says she filed a tax return for $11,000 in earnings last year. She estimates her mother, who was a practicing doctor in Nigeria but now works as an aide at nursing homes, makes under $40,000 a year.
But studies show the Bell family -- which has health insurance and pays its medical bills -- is not typical of many undocumented immigrants who seek medical care in U.S. hospitals.
According to the Pew Hispanic Center, 59 percent of all U.S. illegal immigrants are uninsured, and 45 percent of all illegal immigrant children are uninsured. And while they are not eligible for taxpayer-funded benefits under Medicare, Medicaid, or the Children's Health Insurance Program, uninsured immigrants can receive emergency medical care at hospitals through federal-state subsidies for the poor and people with disabilities.
A 2006 report by the Texas state comptroller estimated illegal immigrants cost state hospitals $1.3 billion a year. A similar report done in 2005 by the Federation of Americans for Immigration Reform estimated the cost to Texas taxpayers at $520 million a year.
Still, no state or federal law prevents illegal immigrants from purchasing their own individual health insurance plans or obtaining insurance through an employer, which many do.
Bell said her disabled sister, now 19, needs round-the-clock attention. "She's total care. She can't walk or talk or communicate. So basically it's like taking care of a 6 month old... My mom works the night shift and I have school and work during the day -- so we just always split it in half. That way my mom is at home during the day with her and then I'm always home at night to stay with her."
"The only question is what happens if I eventually leave home," she said. "But none of us wants to think about that question so we just don't."
Bell, a vibrant personality with a fearless sense of optimism, says she dreams of earning a PhD in economics and becoming a college professor. But as long as she continues to live in the U.S. without legal immigration status and remains responsible for caring for her disabled sister, that dream will be on hold.
"We know, for Bayo, that going to another country is not an option. Because of her medical condition, a lot of countries are unwilling to accept someone like that," said Bell. "And, for me, I don't even know my home country. I don't consider Nigeria my home by any means. I don't have any ties to it."