Foreign-born people account for three-quarters of San Francisco tuberculosis cases, and half of those are among people from China
San Francisco saw 132 cases of active tuberculosis last year, the lowest incidence ever recorded in the city but three times the national average. San Francisco's rate is high in part because of its large immigrant population, an estimated 39 percent of city residents.
Tuberculosis cases have fallen steadily in the United States, from 84,304 in 1953 to 14,093 last year. But the disease has been on the rise worldwide since the 1980s -- particularly in southern Africa and Southeast Asia -- and more than 2 million people die of it annually.
One-third of the world's population carries TB, and if they immigrate they bring it with them.
Foreign-born people account for three-quarters of San Francisco TB cases, and half of those are among people from China, according to the city's Department of Public Health. Other Bay Area counties have a similar pattern. Nationwide, foreign-born people make up 11 percent of the population and 60 percent of TB cases.
For public health workers, treatment of infectious diseases is a balancing act. They must reach out to the communities affected without singling them out for stigma.
"San Francisco is an international city that we take pride in," said Dr. Masae Kawamura, director of the TB Control Section of San Francisco's Department of Public Health. "And with it, we inherit the global diseases of the world."
After outbreaks, Irish immigrants once were associated with cholera, Italians with polio, Chinese with bubonic plague and Jews with tuberculosis.
"This is an old story about American history -- concern about public health and the diseases that immigrants might bring," said Alan Kraut, a history professor at American University in Washington, D.C. "There's nothing particular about being Italian that makes you vulnerable to polio. But if you're poor and living in difficult circumstances, you might be more vulnerable to infection."
The type of work many immigrants perform and a lack of access to health services make many of them vulnerable to infectious disease, said Xochitl Castañeda, director of the California-Mexico Health Initiative at UC Berkeley.
"They don't have enough money to pay for the problem, and what you see is not very happy," said Castañeda, adding that the majority of Mexican immigrants are healthier when they first arrive than they are a decade after settling here.
And when people with active TB aren't treated, they can infect others.
An illegal immigrant from Latin America who had lived at an unlicensed home-child-care center in San Francisco's Mission District off and on since 2002 spurred a tuberculosis outbreak there in 2004, infecting nine children and two adults.
Illegal Immigrants May be Bringing Tuberculosis Into U.S.
Persistent High Incidence of Tuberculosis in Immigrants in a Low-Incidence Country