A Multidrug-Resistant Tuberculosis Outbreak in Kansas, 2021–2022

This page summarizes a report in CDC's MMWR by local, state, CDC and regional TB center staff. The outbreak was identified during November 2021–November 2022; treatment results are as of September 2023.

Tuberculosis (TB) is uncommon in Kansas: 37–43 cases were reported each year during 2019–2021. In 2022 the count rose to 52, and an outbreak of multidrug-resistant (MDR) TB in four households of a low-income, underserved urban community drove the rise.

MDR TB is, by definition, resistant to at least isoniazid and rifampin, two of the most effective TB medicines. In the United States it is uncommon. In 2021 it was present at first diagnosis in only 77 (1.0%) of 7,882 reported TB cases, and it usually occurs in people born in other countries who were likely infected years earlier while living there.

How the outbreak was found

• November 2021, household A. An infant was hospitalized with pulmonary and meningeal TB. A DNA test for an rpoB gene mutation first detected rifampin resistance. Sequencing and growth-based testing confirmed it and found resistance to isoniazid, pyrazinamide and ethambutol as well — all four first-line drugs — but none to second-line drugs. The local health department's investigation found four more household members with MDR TB, among them a severely ill adult with smear-positive cavitary lung disease who had had symptoms since June 2021.
• January 2022, household B. A young child was hospitalized with pulmonary TB and lymphadenitis. Mycobacterium tuberculosis grew from a cervical lymph node biopsy, with the same resistance pattern as household A. Hospital staff noticed the child's mother, who was pregnant, coughing; she was evaluated and diagnosed with pulmonary MDR TB. Contact tracing then found four more household members with MDR TB, including a severely ill young adult with cavitary lung lesions who had had symptoms since at least September 2021.
• The connections. Households A and B lived in the same apartment complex and socialized a great deal, and adults from both shared a car to the same workplace. Two apartment households in another neighborhood, C and D, were also linked to the families. A young teenager in household C who had spent time in both A and B was diagnosed with pulmonary MDR TB and extrapulmonary TB vasculitis.
• July 2022, household E. An unexpected genotype match turned up in a child with MDR TB in a neighboring state. Further investigation showed that the young adult from household B knew household E and had spent time in its home while infectious. That brought the outbreak's total to 14.

Contacts in the households, a school and a workplace were tested when first identified and again 8 weeks after their last exposure to a household member with TB, with an interferon-gamma release assay blood test or a tuberculin skin test.

The count

Most of the seven adults were born outside the United States, in a country that had an MDR TB outbreak with the same genotype during 2007–2009. Most of the six children were U.S.-born and became infected in Kansas. The most recent person found to have extrapulmonary TB was diagnosed in November 2022.

What the genomes showed

CDC's National TB Molecular Surveillance Center sequenced the whole genome of every culture-confirmed isolate. The isolates differed by at most three single nucleotide polymorphisms, which supports transmission within one social network. They were also closely related to isolates from earlier outbreaks in the Federated States of Micronesia (2007–2009) and Guam (2009–2016), and some adults in this outbreak had lived in those places during those outbreaks.

Treatment

Every household contact was checked for disease and LTBI with a blood or skin test, chest imaging and sputum testing. Each person with active disease got an individual regimen, designed after expert consultation through the Heartland National Tuberculosis Center and given as daily, in-person directly observed therapy.

The children were a particular challenge because BPaLM has not been studied in children under 15. Delamanid, an MDR TB medicine used in Europe, was authorized by the Food and Drug Administration for compassionate use after review by the Kansas Department of Health and Environment's Institutional Review Board.

Adherence was excellent among everyone who started treatment:

• As of September 2023, 13 of the 14 people with MDR TB disease had completed treatment.
• One adult clinically diagnosed with extrapulmonary TB declined treatment despite extensive efforts by public health staff and clinicians. Local staff keep in careful contact in case the person wants treatment, or the disease progresses and becomes a risk to the community.
• All nine people treated for LTBI finished without developing disease or complications.

Everyone treated for disease or LTBI will be seen by public health clinicians every 6 months for at least 2 years after finishing, with a chest radiograph, a review of signs and symptoms, and a physical exam.

Lessons

• Rare, and costly. MDR TB outbreaks have been exceptionally rare in the United States since the 1990s. This one infected several U.S.-born children living in Kansas and contributed to a national increase in pediatric TB reported in 2022. MDR TB brings more illness and cost than drug-susceptible TB, and the newer drugs needed careful monitoring to secure a cure and avoid further resistance.
• No single source. Both first cases, the infant and the young child, had a plausible source at home: an adult born outside the United States with a long illness and infectious period. At least one of those adults was likely infected overseas years earlier and developed active disease after moving to Kansas. Neither was diagnosed for many months, which allowed more spread.
• A strained health department. The response put heavy financial, staffing and capacity strain on the local health department, already diminished by nearly 2 years of COVID-19 response. Relationships with schools, hospitals and other partners built during COVID-19 prevention work helped it coordinate efficiently.
• A warning for low-TB places. Sustained declines in TB are not assured. Control depends on continually finding and treating LTBI, and on a swift, multifaceted response to every new diagnosis.

Sources

• Groenweghe E, Swensson L, Winans KD, et al. "Outbreak of Multidrug-Resistant Tuberculosis — Kansas, 2021–2022." MMWR 72(35). https://www.cdc.gov/mmwr/volumes/72/wr/mm7235a4.htm
• CDC, multidrug-resistant TB fact sheet: https://www.cdc.gov/tb/publications/factsheets/drtb/mdrtb.htm
• The report says nine of the 13 Kansas patients were culture-confirmed and five had clinically verified disease, which does not add up to 13; this page gives neither split.