New TB Threat: Global Ties Bring an Ancient Disease to Silicon Valley

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Last year, tuberculosis increased in four of the Bay Area’s five largest counties, and the San Jose area in 2006 had the highest TB rate of any large American metro area, according to data from the U.S. Centers for Disease Control and Prevention and the California Department of Public Health. San Francisco, after an outbreak of TB among Latino day workers in the Mission district, has the highest TB rate of any county in California—quadruple the U.S. rate.

From the bodies of Peruvian mummies to 21st-century tech workers, tuberculosis has been mankind’s dark partner for centuries—a highly infectious disease that never followed the path to eradication of smallpox and polio. One in three people worldwide are infected, and 1.7 million died last year, mostly in poor countries where people lack the access to detection and treatment available in the United States.

No case of TB is easy. The waxy-sheathed, rod-shaped, slow-growing bacteria, if untreated, colonizes the lungs, creating such dense cavities of disease that pieces must sometimes be excised. TB spreads through the air; untreated, one person infects 10 to 15 people a year, according to the World Health Organization.

But among public health officials, nothing is more worrisome than the relative handful of drug-resistant TB cases. WHO and U.S. experts are warily watching the record level of such cases—found from former Soviet prisons to remote provinces in China—as hints of something even scarier on the horizon.

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Treating one drug-resistant case can easily cost several hundred thousand dollars or more—the bill often ends up with the county health department if a patient lacks insurance. And in a growing number of extremely resistant cases—including a few in the Bay Area—there are no drugs that can cure the disease, raising the specter of an infectious, incurable, potentially fatal infection.

With California in a budget crisis—and the state’s total number of TB cases declining—a disaster which hasn’t happened yet is not a high priority for politicians. But that is precisely what worries Bay Area TB officials. They say emerging drug resistance, global travel connections, and Gov. Arnold Schwarzenegger’s plans to cut TB spending will all handicap California’s ability to protect residents from dangerous drug-resistant TB.

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Demographics

Valley’s strong links to other countries If affluent, modern Silicon Valley seems an unlikely hunting ground for a disease often presumed a medieval scourge, nothing could be more wrong. This region has intimate ties to countries with the world’s highest TB burdens, countries where the lack of access to antibiotics and basic health care has allowed the disease to flourish in the 21st century.

Ninety percent of Santa Clara County’s 241 TB cases in 2007 were in students, immigrants, temporary workers, tourists and others born in other countries. At the same time, the number of multi-drug-resistant cases in the county—bacteria resistant to isoniazid and rifampin, the first-line TB antibiotics—jumped from two to seven.

The top five countries of origin for foreign-born people with TB are Mexico, the Philippines, Vietnam, India and China, according to the CDC. Those nationalities are also Santa Clara County’s largest five foreign-born populations. At 430,000 people, they are one-quarter of the county’s total population.

“Our TB reflects the countries of origin that our patients come from, and it’s the Philippines and Vietnam and India where there is a lot of drug resistance,” said Dr. Sundari Mase, Santa Clara County’s former TB control officer, now with the CDC.

Many are not recent immigrants—two-thirds of Santa Clara County’s foreign-born cases have been in the United States for at least five years. In that sense, TB is a public health issue, not an immigration issue, heath officials say.

State health officials estimate there are 2 million foreign-born residents of California infected with latent TB. The great majority will never get sick, but if their immune systems weaken—by way of HIV infection, diabetes, aging or immune-suppressing drugs—their TB could multiply, and they could transmit the disease.

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Loopholes

Screening isn’t always effective The United States screens legal immigrants and refugees for TB before they are allowed to enter the country, by checking medical histories and requiring a chest X-ray for those at risk. But Bay Area health officials say there are loopholes in the nation’s defenses, and that budget cuts will only make the gaps bigger.

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Canada prevents an estimated 600 TB cases a year by screening everyone who plans to stay in the country permanently, for longer than six months if they are coming from a country with a high incidence of TB, or for any length of time if they will be working in health care, education, child care or domestic work, said Dr. Edward Ellis, manager of TB control for the Public Health Agency of Canada.

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The cost of every TB case to local taxpayers is significant.

Santa Clara County spent an average of $18,000 a case in 2007—about $4.3 million total—for drugs, testing and for the labor-intensive contact investigation required for families, co-workers or schoolmates who have contact with an infectious person.

With state and local funding in doubt, Fenstersheib, the county health officer, went to Washington in March to lobby Silicon Valley’s congressional representatives to have Santa Clara County join the dozen U.S. cities and counties that get direct federal TB funding.

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