Since the 1950s, tuberculosis cases have declined dramatically in Maine and in the nation, thanks to a widespread public health campaign and the development of effective drug combinations to treat the disease and halt its spread.
But Maine has seen a small uptick in cases in recent years, coupled with the troubling appearance of treatment-resistant strains of the TB bacterium. That has some medical experts worried that the disease could gain traction and advocating for broader testing to catch TB in its non-contagious latent phase.
The increase may be attributable to a rise in the state’s foreign-born population of refugees and asylum seekers, intravenous drug use and the limited use of TB screening and testing.
Nationally, the rate of TB diagnoses plummeted from 52.6 cases per 100,000 Americans in 1953 to just 2.9 cases per 100,000 in 2016, according to data from the U.S. Centers for Disease Control and Prevention. In Maine, the incidence of TB has, until recently, followed a similar trajectory, leading to the closure of private sanatoriums in the 1960s and dropping the case rate into the single digits.
Since 2007, the rate of TB cases in Maine had hovered around 1 case or fewer per 100,000 residents. But that rate rose to 1.4 in in 2015, with 18 cases of active disease reported, and to 1.7 in 2016, with 23 cases reported. The number of reported cases dropped back to 14 in 2017.
Still, the increase from 2014 to 2016 is disturbing, said Dr. August Valenti, an infectious disease specialist and epidemiologist at Maine Medical Center in Portland. The identification of two drug-resistant TB cases in 2015 and three in 2016, he said, is “very significant,” the more so given that one was considered “extensively drug-resistant” and did not respond to a powerful second tier of TB medications.
“We’d like to see the percentage of cases decline over the years,” Valenti said.
The national incidence of all drug-resistant TB cases in 2016 was about 670. The incidence of drug-resistant cases in 2017, in Maine and nationally, is not yet available.
“We are very interested in getting people identified with TB more quickly,” Valenti said, ”because we don’t want that drug resistance to spread.”
A robust public health response to managing TB is essential, he said, since delayed diagnosis and incomplete treatment are leading causes of drug resistance.
Valenti says Maine should aggressively address the underlying and much larger incidence of latent tuberculosis illness, also known as LTBI. Because LTBI doesn’t cause symptoms, individuals may not realize they’re infected, he said.
“You want to get [LTBI] treated before it has a chance to become active,” he said.
Individuals exposed to the TB bacterium may develop LTBI when their healthy immune system prevents the development of active disease. These individuals test positive for TB on a skin test, but they don’t have symptoms and cannot pass TB to others. LTBI can be effectively treated with medication.
However, in about 5 to 10 percent of cases, untreated LTBI turns into active disease, often as a result of immunosuppression because of other illnesses. And it may take weeks or months before the symptoms — fever, fatigue, night sweats and a persistent cough that produces thick, cloudy or bloody sputum from the lungs — lead to a diagnosis of TB. Meanwhile, the individual is highly contagious and can easily pass the disease to others through airborne droplets released by coughing or sneezing.
TB can be fatal and is a leading cause of death in people with HIV.
LTBI, unlike active TB, is not mandatory to report, so its incidence is not accurately tracked. In Maine, the state CDC received reports of 493 people with LTBI in 2015. In 2016, the number rose to 551. The actual incidence is thought to be significantly higher.
“It is much better to treat someone with a latent infection than with active disease,” said State Epidemiologist Dr. Siiri Bennett at the Maine CDC.
For one thing, the drug therapy is less costly, less lengthy and less likely to cause side effects, she said. Curing a case of LTBI before it has a chance to turn active also means the bacterium won’t be passed to others.
Bennett said the recent cases of drug-resistant TB in Maine are concerning and likely reflect a broader problem of antibiotic resistance across many disease organisms.
Treatment for active TB and LTBI is generally covered by private and public health plans. But for those who lack coverage and can’t afford to pay, the Maine Department of Health and Human Services will pick up some or all of the tab. Drug resistance, which is more likely to require hospitalization, poses a significant additional expense.
For example, a 2016 request for payment for an “extended stay for a patient with treatment-resistant tuberculosis” at Maine Medical Center totaled more than $65,000.
For active TB, treatment can include daily dosing with four different drugs for up to nine months. LTBI typically calls for just one medication, less frequent dosing and a duration of three to six months.
Bennett said the state works with health providers and others in the community to ensure that patients with either TB or LTBI comply with their demanding medication regimens. This support can include having nurses directly observe patients as they take their medicines as well as monitoring for side effects and teaching strategies to avoid spreading TB to others.
Though the ranks of public health nurses have dropped sharply under the administration of Gov. Paul LePage, Bennett said, “We follow up with every single case to ensure people get the treatment they need.”
Widespread in countries with high rates of poverty, including India, China, the Philippines and Nigeria, TB retains a small but stubborn foothold in the United States. Among those most at risk for developing TB in the U.S., according to the U.S. CDC, are people who have immigrated from areas of the world with high rates of TB, people who live and work in correctional facilities and homeless shelters, intravenous drug users and those with HIV.
In Maine, the majority of active TB cases reported in recent years have been identified in Androscoggin County, home to a substantial population of refugees and asylum seekers from Somalia and other African nations. More than 90 percent of the 493 cases of LTBI reported in 2015 were “among persons who are foreign born,” according to Maine CDC reports.
Immigrants newly arrived in this country are routinely tested and treated for transmissible diseases, and health care providers are likely to be on the lookout for TB in this high-risk population.
Valenti says that’s not enough. He recommends that all who spend time in countries where TB is common get tested, including students and business travelers. Those who work in hospitals, prisons and homeless shelters should also be checked at regular intervals, he said, and more public education about preventing the spread of tuberculosis is key.
“The greatest barrier [to expanded testing] is the healthcare provider not thinking about TB risk when assessing patients,” Valenti said in an email. “The second greatest barrier is getting tests paid for.”
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