In November 2021, Kansas experienced an alarming outbreak of multidrug-resistant tuberculosis (TB). This outbreak, which lasted for a year and affected 13 individuals across four households in Kansas City, highlighted the potential dangers of a disease that was once believed to be under control. What made this outbreak particularly concerning was the fact that most of the children affected were U.S.-born, emphasizing that the threat of TB is not limited to individuals born outside of the country.
The outbreak served as a stark reminder that sustained declines in TB incidence cannot be taken for granted. Elizabeth Groenweghe and her colleagues from the Unified Government Public Health Department in Kansas City emphasized the importance of ongoing identification, treatment, and prevention of latent TB infection. They stressed the need for a swift and multifaceted public health response for every individual newly diagnosed with TB.
The outbreak involved households A, B, C, and D, with connections extending beyond these households. Nine additional individuals in the affected households were diagnosed with latent TB infections. Furthermore, a child in a neighboring state was identified in July 2022 with an epidemiologic connection to the Kansas outbreak. This expansion of the outbreak raised concerns about the potential for further transmission and underscored the need for effective containment efforts.
All active infection isolates in the outbreak were resistant to rifampin, isoniazid, pyrazinamide, and ethambutol, which are first-line treatments for TB. However, these strains were susceptible to second-line therapeutics. The initial case in the outbreak, an infant, was found to be infected with a strain resistant to all four first-line drugs. The identification of drug-resistant strains highlights the urgency of developing new treatments and strengthening the fight against resistance.
The investigation revealed an intricate network of transmission within and between households. Household A, where the outbreak began, had four latent infections and four active infections, including a severely ill adult with pulmonary cavitary disease. Household B, located in the same apartment building as household A, had connections through extensive socialization, car-sharing, and commuting. Household B experienced active infections, including a young child and the child’s pregnant mother.
Treating the affected individuals proved to be a significant challenge, particularly for children. Most of the adults and an older teenager in household A received a 26-week treatment regimen consisting of bedaquiline, pretomanid, linezolid, and moxifloxacin. The pregnant woman’s treatment included additional medication due to her pregnancy and breastfeeding. Three of the children received a regimen that included delamanid, a multidrug-resistant TB medication authorized for compassionate use. Individual treatment plans were tailored to each case, and by September 2023, 13 out of 14 patients had completed treatment.
In addition to treatment, the importance of long-term monitoring and surveillance cannot be overstated. The nine individuals diagnosed with latent TB infections were treated prophylactically with daily moxifloxacin for six months, all of whom completed treatment without developing the disease or complications. Local public health officials will continue to closely monitor all patients every six months for at least two years, using various diagnostic tools to assess their progress.
To better understand the outbreak, whole-genome sequencing was conducted on isolates from nine individuals with culture-confirmed active TB. The analysis revealed that the isolates were very similar, differing by only up to three single nucleotide polymorphisms. This finding supported the hypothesis that the outbreak was locally transmitted within the social setting of the affected families. Moreover, the sequencing also established genetic ties between the Kansas outbreak and previous outbreaks in the Federated States of Micronesia and Guam.
The Kansas TB outbreak exposed the vulnerabilities within public health systems and highlighted the strain it puts on local health departments. The ongoing COVID-19 pandemic further weakened the capacity of these departments, making it even more challenging to respond effectively to TB outbreaks. However, the outbreak also revealed the importance of collaborations established during COVID-19 prevention efforts. Positive working relationships with community partners, such as schools and hospitals, facilitated efficient coordination of the outbreak response.
The multidrug-resistant TB outbreak in Kansas served as a wake-up call regarding the persistent threat of TB. The outbreak affected both U.S.-born individuals and those born outside of the country, dispelling any misconception that TB is solely an imported disease. Greater emphasis on ongoing identification, treatment, and prevention of latent TB infections is crucial to combatting this disease effectively. The outbreak also shed light on the need for continuous monitoring, treatment, and surveillance, as well as the challenges posed by drug-resistant strains. By learning from this outbreak, public health officials can better prepare for and respond to future TB outbreaks.