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."