A Ramsey County-based outbreak of multi-drug resistant tuberculosis has grown to 17 cases, making it the largest in the country and prompting state health officials to monitor several hundred more people who may have been exposed.

The case presents another significant and costly challenge for public health officials in Minnesota, who battled a stubborn measles outbreak this year. And patients affected by the outbreak have to endure long hospitalizations, close monitoring and a costly medication regimen that has more side effects than the two first-line antibiotics that are ineffective against this strain.

The outbreak has primarily affected elderly residents in the Hmong community, with 10 cases linked to a senior center where the first case was detected in 2016. Four other Hmong residents were also infected.

So far six of the 17 people have died, three as a direct result of tuberculosis.

Because tuberculosis is not easy to catch, this outbreak presents the greatest risk to the social groups and families of those infected, who are susceptible to the disease through repeated exposure. The disease is spread through the air when someone with infected lungs talks, sneezes, coughs or sings.

Some of the first transmissions occurred among a group of seniors who regularly played cards at the senior center.

But one of the card players had been sick and infectious for five years before diagnosis. That has left public health officials playing catch up in an effort to find everyone who is at risk.

The county has funded additional public health workers and the state has tapped nearly $225,000 in emergency funds to limit spread of the disease.

"We know we are already seeing more cases than we would have anticipated, and we far outnumber cases in other parts of the country," said Anne Barry, director of the St. Paul-Ramsey Public Health Department.

More than 350 people, mostly those in other senior centers that serve the Hmong community and family members of those infected, need to be assessed or reassessed for signs of infection.

However, about 150 potential contacts known to investigators had incomplete date of birth or address information, complicating the efforts to track them down. Disease investigators faced similar tracking problems during the early days of this year's measles outbreak, which also was the largest in the country.

Latent but risky

Testing on 125 people has already turned up 58 cases of latent tuberculosis infection, meaning they carry the disease, but have no symptoms and cannot pass it on to others.

Like those who show symptoms, those with latent infections are being urged to take the second tier antibiotics, but that treatment can last 18 to 24 months and cost as much as $134,000. By comparison, tuberculosis that is not resistant to first-line drugs requires at least six months of drugs at a cost of $17,000.

"In the case of these individuals, if there wasn't evidence that they had been exposed to multi-drug resistant tuberculosis, then they would have just been recommended to get the normal course of treatment," said Kris Ehresmann, infectious disease director at the Minnesota Health Department. "But the treatment is arduous and has many side effects."

There is no test to determine whether latent tuberculosis is resistant to certain medications.

Some of those in the current outbreak are refugees who tested positive for latent tuberculosis when they entered this country, many decades ago. At the time, they were treated using the first-line drugs, which turned out to be ineffective against the tuberculosis bacteria.

About 10 percent of those with latent tuberculosis go on to develop symptoms, especially if they have chronic health conditions or as they age and their immune systems weaken.

Thai refugee camps

At least four of the 10 Hmong elders who were infected in the senior center had spent time at a camp in Thailand that housed many Hmong refugees and is known to have high tuberculosis infection rates.

Many affected Hmong elders don't understand why they need to be treated again for tuberculosis after many were given medication when they arrived here.

"It is not just translating for language, it is translating for culture," said Barry, whose department has long employed workers who grew up in the Hmong community. "An emergency is not the best time to build a relationship."

In addition to reaching out to Hmong health care workers and news media, public health officials have also worked with the Hmong 18 Council, which represents leaders of the 18 Hmong clans in Minnesota, to spread the word.

"It is not easy for everybody to understand. It is a very serious situation, but people often don't understand until it is too late," said Wa Houa Vue, president of the council. "We still can do more."

Tuberculosis symptoms include a cough lasting more than three weeks, weight loss, night sweats and fever. Although it typically affects the lungs, if left untreated it can lead to spinal pain, joint damage, meningitis and damage to the liver, kidneys and heart.

"If anyone has the symptoms, please see their doctors and make sure they know what it is," said Vue.