Amid an east metro tuberculosis outbreak, officials say the few cases present in Washington County are unlikely to spread.
The county treated two cases last year, and are working with three active tuberculosis infections this year that had been contracted before a recent Ramsey County outbreak began.
The cases in Washington County have not been the drug-resistant strains seen in the Hmong residents at a senior center in Ramsey County that has killed six — three as a direct result of the disease — and infected several others, the St. Paul Pioneer Press reported.
Most metro counties, including Washington and Dakota, report a handful of tuberculosis cases each year, but the majority of the cases are not drug resistant.
Kristine Lees, supervisor of the disease prevention control team in Dakota County, said strains are occasionally resistant to one possible treatment, though that's rare, and multi-drug resistance is even more rare.
Compared to the measles outbreak earlier this year, epidemiologist Kris Keller of Washington County said tuberculosis outbreaks are more likely to stay contained.
Tuberculosis has a different exposure time, level of infectiousness and does not stay airborne as long as diseases such as measles.
Many of the cases they currently are treating were likely latent for a long time before patients began showing symptoms.
When active cases show up, patients go through at least six months of directly observed treatment. The average time is nine months. Washington County usually has public health nurses checking in monthly on between 10 and 20 latent cases.
Public health nurse Julie Winner said latent cases often become active when the patient is older, and immunity is lowered or have contracted another disease.
Drug resistance can be triggered by incomplete treatment, which is why public health nurses visit a patient every day on average for about nine months, to provide directly observed treatment (DOT).
"The goal is to make sure that somebody does get the right medication for the whole treatment to prevent the bacteria to become fully resistant," Lees said. "That's part of the reason we do DOT, to make sure resistance (doesn't occur)."
Jill Timm, supervisor of disease prevention and control for Washington County, said many of the patients' cases — both countywide and statewide — originated when they were living in foreign countries, or contracted the infection by having connections to other countries.
Over 80 percent of recorded cases are in non-U.S. born residents, according to the Minnesota Department of Health, and the majority were born in African or Asian countries.
"I think the risk will always be there for a couple cases a year, so long a TB still is common in other parts of the world," Lees said. "There's a lot of travel, so there's always that risk."
Before the outbreak, cases of tuberculosis in Minnesota — as well as the country — have been generally trending downward.
Washington County has slightly decreased in the last decade or so, moving from three or four per year to one or two.