A shift in the population of San Mateo County has led to tuberculosis rates that outpace the state and national average, according to a county health report.
One of the key findings in San Mateo County's 2013 Community Health Needs Assessment was that, "Tuberculosis rates are increasing [in the county] and are disproportionate to declines seen in the rest of the state and the nation." The numbers in the report, which is sponsored by The Healthy Community Collaborative of San Mateo County, span from 1991 through 2010.
Robyn Thaw of the San Mateo County Health System said she believes that rates have actually been decreasing in the county since 2010.
"There is not a significant increase in the number of TB cases in San Mateo County and in fact, over the past three years, there has been a decrease," Thaw said.
But the number of cases from year to year, whether it represents a slight increase or decrease, is beside the point, according to Dr. Scott Morrow, San Mateo County's health officer.
"So when you look at year-to-year rates, it doesn't really mean anything. You really need to look at the trend over decades. That will really tell you what's going on in the community around TB," Morrow said.
Tuberculosis, caused by a tiny germ, a bacterium called Mycobacterium tuberculosis, was a major disease in the U.S. in the 1940s and '50s. The government successfully quelled it enough at that point to cause a marked decline in cases, but there was a resurgence again in the 1980s. While the disease is curable, if left untreated it can be fatal. TB usually affects the lungs, but it sometimes harms other parts of the body, like the brain, kidneys, lymph nodes or spine.
Tuberculosis is an extremely complex disease, Morrow said, and nearly one-third of the human population harbors tuberculosis in their bodies. Only around 10 percent of those cases ever become active, and those cases are the ones on which the county places its focus, with daily monitored drug treatments that can last from nine months to up to 24 months in some cases.
Many of the cases today, Morrow said, don't originate in the U.S. but are brought here inside the bodies of foreign-born immigrants whose home countries don't track and regulate TB as reliably as the U.S.
"It's the most common infectious disease on the planet that we know about. So most of the disease that we have here come from a reservoir of infection from other places," he said. "In San Mateo County, it happens to be most of them from the Philippines. Because there's a lot of TB in the Philippines, and a lot of Philippine immigrants in San Mateo County."
When a patient is diagnosed as having TB, their doctor immediately reports the case to the county health department, and the patient is then administered treatment on a daily basis. A county health representative will knock on the patient's door every day with their dose of medication and make sure that person takes it. It's expensive, Morrow said, but it's a top priority in the county.
Morrow hopes to see the rates decrease steadily.
"The long-term trend in the U.S. with the current immigration pattern is a slow downward trend, with California going a little bit more rapidly," he said. "We'll probably see kind of a bumping along up and down year to year for the next 10 to 20 years."