Sacramento’s disease detectives on the trail of a virulent tuberculosis outbreak

If Etta Dixon knocks on your door, chances are you’re harboring a very small and nasty fugitive.

A communicable-diseases investigator with the Sacramento County Public Health division, Dixon has been in all kinds of homes recently searching for traces of a culprit that’s already sickened about 60 victims this year: tuberculosis.

“I absolutely know what I’m looking for,” she said. “It’d be nice if it’s in a nice, tidy package, but that’s not how diseases work.”

The most recent outbreak of the airborne bacteria—at one time the biggest killer in America—infected a female student at Grant Union High School in late February. Three of her classmates, as well as four friends and relatives, became ill with active TB, which carries many of the same symptoms as the flu or pneumonia and can prove fatal if untreated, especially among older, vulnerable populations with compromised immune systems.

Health officials don’t yet know how their teenage Patient Zero contracted the disease, said Dr. Olivia Kasirye, the county’s public-health officer. “And sometimes we never know why.”

That’s because TB can lie dormant in a person for months, even years, before symptoms manifest, if they ever do. According to the Centers for Disease Control and Prevention, one-third of the world’s population is infected with TB, though only about 9 million grew sick in 2012. Kasirye said about 10 percent of those infected with TB in the United States will develop active symptoms.

But infection rates have declined. Last year in California, there were an estimated 2,170 cases—nearly six for every 100,000 residents—down from 5,382 cases in 1992, says the California Department of Public Health’s Tuberculosis Control Branch.

The most vulnerable demographics appear to be foreign-born residents and those who are 65 and older. Men also report higher incidents of TB, accounting for approximately 61 percent of California’s 2013 caseload.

In the past two years, Sacramento County ranked 13th and 19th among all California counties when it comes to the rate of reported TB cases. Officials totaled 84 cases last year.

“We really believe it’s a community issue, not a school issue,” said Bill McGuire, deputy superintendent of the Twin Rivers Unified School District, to which Grant Union belongs. The district presented a 15-page action plan during a special school board meeting this past Monday and scheduled an August 22 screening for students who have yet to be cleared. McGuire stressed that the four students who did have active cases completed their treatment and are no longer sick.

A shared ventilation system at Grant may have helped spread the current strain to adjoining classrooms. More than 400 students and staffers have been screened thus far, with 122 receiving preventative treatment after showing signs of exposure.

They’re not sick or contagious, though—a message public-health officials have struggled to articulate to a nervous community.

Some of the misconceptions officials have tried to debunk are that there’s a vaccine for TB (there isn’t), exposure is the same as infection (it’s not), and that the response to the high-school outbreak was slow (not exactly).

Grant’s Patient Zero was isolated and receiving treatment the same day the county was contacted, said Angie Butters, program manager of the health division’s Chest Clinic. Hospitals and other medical practitioners are required to notify the county of possible TB cases within 24 hours. That doesn’t always happen—and there are some misdiagnoses, especially during flu season—but there are backup protocols in place to catch what ER docs occasionally miss.

“TB is difficult because you can’t depend on just one test,” Kasirye said. “And you have to do them in a certain order.”

There’s the initial skin test, followed by a pulmonary X-ray and a sputum diagnostic. An abnormal X-ray can show large cloudy areas where TB bacteria has eaten into the lungs, but isn’t always definitive. And Kasirye said a sputum culture can take five weeks to return from the lab, and it’s often necessary to push treatment before that final confirmation comes in.

To treat the active strain, medical practitioners usually prescribe a four-drug cocktail that has to be administered daily for a minimum of six months, with public-health nurses visiting patients every day at home, work or elsewhere to make sure it’s done right. “They just spend the whole day going from one house to another,” Kasirye said of her nurses.

Aside from the daily visits, patients also come in for monthly blood tests to monitor their status and detect potential side effects from the drugs, which can sometimes affect liver health.

Every collected bacteria specimen is sent to a reference lab for fingerprintlike genotyping that can discern transmission patterns across multiple jurisdictions, Kasirye said. Public-health spokeswoman Laura McCasland compared the process to a criminal investigation, making people like Dixon something of a disease detective. At times, that’s meant interviewing upward of 200 people, including homeless individuals exhibiting mental-health issues. “One thing that you need to be careful of is that you’re targeting the right people,” she said.

TB is the Moriarty to her Sherlock Holmes. And the game is always afoot.