Kansas City combats one of the worst tuberculosis outbreaks in recent US history

Two patients have died since spread of disease was identified in January 2024, reports Alan Booth, Senior Editor at International Labmate

Kansas in the United States has been experiencing one of the largest tuberculosis (TB) outbreaks since the 1950s, with epicentres of infection being in Wyandotte and Johnson counties which lie within the metropolitan area of Kansas City, Kansas. The outbreak, which began in January 2024, has resulted in two deaths being reported.

Currently there are 67 active cases that have been reported, with 60 in Wyandotte County and seven in Johnson County. 35 of the active cases and 32 of the latent cases have completed courses of treatment.

Additionally, 79 individuals have been diagnosed with the latent form of TB, meaning that they have been infected by the bacteria but are not contagious. While latent TB does not cause symptoms, it can develop into an active infection.

TB is a bacterial infection – caused by the Mycobacterium tuberculosis which is also known as ‘Koch’s bacillus’ – that primarily affects the lungs and spreads through airborne particles released by coughing, sneezing, speaking or singing. Common symptoms include a prolonged cough, fever, weight loss, chest pain, weakness and coughing up blood or mucus.

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These case numbers are, however, being described as provisional and yet to be officially confirmed by the Center for Disease Control (CDC) which is expected to do so in March.

Health officials at the Kansas State Department of Health and Environment (KDHE) have been calling it the largest TB outbreak in recent US history with high levels of response from health officials which has included the CDC deploying four of its staff, in recent weeks, to assist with the process of contact tracing, disease testing and wider public education efforts.

Kansas State health officials have emphasised that the risk to the public remains very low. However, the outbreak is ongoing, and there is a possibility of more cases emerging. The KDHE is requiring that ‘mandated reporters’ – which include clinicians and other persons licensed by the state to provide health services – make a record with the state’s epidemiology hotline of all suspected cases of active tuberculosis within four hours of their suspicion being raised.

All cases of latent TB infection also must be recorded with both the appropriate county local health department and KDHE within at most 24 hours.

The KDHE is not requiring the public to mask as a precaution. But for those caring for patients with respiratory TB a N95 mask, or better, would be needed as part of the healthcare professional’s personal protective equipment. Simple facemasks are not able to filter out the mycobacteria that causes TB.

To date, there has been no data reported on demographics or risk factors or clinical status of any of these patients. However, according to data published in the Emerging Infectious Disease article titled: ‘Tuberculosis Outbreak Investigations in the United States, 2002–2008’, TB risk factors for patients in CDC-investigated outbreaks have included comorbidities such as HIV infection, diabetes and previous incomplete treatment (antimicrobial resistance) alongside social factors such as substance use and alcohol use disorder.

 “US outbreaks have varied over time. In more modern times, medical comorbidities have factored heavily. There was a significant spike in TB cases fuelled by the immunosuppression of the AIDS pandemic. We see chronic medical conditions such as kidney disease, diabetes, liver disease, alcohol use disorder, etc. increasing the risk of TB,” according to Dr David Cennimo, Associate Professor of Medicine – Paediatrics Infectious Disease – at New Jersey Medical School and the Global Tuberculosis Institute at Rutgers, State University of New Jersey.

“Congregated living conditions can facilitate the spread of infection as the airborne germs can [get into] contact with more people. In the past, prisons and shelters have been epicentres of outbreaks. Knowing this, many of these spaces have instituted TB screening to decrease risk.”

If left untreated, TB can be fatal, but it is curable with antibiotics, typically requiring a combination treatment regimen of four drugs in the initial treatment phase, followed by two others to be taken for several months. Patients usually become non-infectious after 14 days of treatment commencing.

In the US, TB cases have been seen to have increased annually from 2020 to 2023 after nearly three decades of decline. The Bacillus Calmette-Guérin (BCG) vaccine is no longer commonly used in the US or offered as a routine public health measure during an outbreak with no significant use in more than 50 years. Routine infant immunisation ended in the UK in 2005.

“The BCG vaccine has been most consistently shown to help protect infants against severe disease such as TB meningitis. But it would have limited effect in a general population even during an outbreak. Resources are better spent on intensively contact tracing and case finding.

“Historically, TB diagnoses have been delayed because the infection was not thought of [these days by many doctors]. Testing and treatment can be delayed if you do not consider the patient could have TB,” said Dr Cennimo.

“Also, patients who have less access to care are always at higher risk of delayed diagnosis. In the US, TB is [considered] such a public health threat, however, the public health apparatus usually steps in and facilitates effective treatment. Investing in public health infrastructure is crucial for effective case detection, treatment, and prevention strategies,” he said.

Local health departments in Kansas are conducting free testing for individuals, regardless of insurance coverage.

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“Contact investigations are a hallmark of TB control. Ideally, we identify people before they develop an active disease and treat latent TB to prevent its progression. There is the health benefit for the individual who never gets sick [but also for] society because we are potentially breaking a chain for further transmissions.

Dr Cennimo concluded that: “investigations can fail, for many reasons, but possibly because people are afraid to be identified. And so, in the end more people get sick.” 

In 2023, TB was the world's deadliest infectious disease, responsible for approximately 1.25 million deaths. Globally, about 25% of the population carries TB bacteria, but only between five and 10 per cent go on to develop symptoms.

In 2024, Missouri reported 87 tuberculosis (TB) cases, including 33 in the Kansas City, Missouri area. Kansas City sits in the northeast corner of Kansas and crosses over the border into the state of Missouri. In Missouri there have only been four reported case of in 2025 and none of these active cases are linked to the outbreak that is occuring in Kansas, said a spokesperson for the Missouri Department of Health and Senior Services.

Following 30 years of decline, TB cases have increased in the US in the period 2020-2023, with the public developing more widely sceptical views of public health efforts since the COVID-19 pandemic.

But Dr Cennimo said that there are other, more mundane and practical, factors at play: “COVID pulled a great deal of public health resources [to combat the pandemic] so our TB screening programs, and other control efforts declined.

“We are now seeing an uptick in TB cases in both US born and non-US born. To me, this suggests a component is a failure to identify latent TB [in the population] and treat it before reactivation.”

The overwhelmingly predominant spread of TB is airborne, from person to person, with little impact being seen from fomites – a material, object or surface which can carry infection – according to the medical reference publication, the MSD Manual.

Previous recent outbreaks include one in Georgia from 2015 to 2017, where more than 170 active cases and another 400 latent cases were linked to homeless shelters. Another nationwide outbreak occurred with 113 TB cases in 2021 which was linked to transplants of contaminated bone tissue.

“There have been isolated cases of spread form infected biological material such as bone tissue to be used in transplants. Humans have also been infected by drinking unpasteurised milk that was TB infected, but this is exceedingly rare in the US,” added Dr Cennimo.