Investigators say a rare outbreak of multidrug-resistant tuberculosis (MDR-TB) in a social network in Kansas provides a "cautionary tale" for areas with low TB incidence.

The outbreak, described today in Morbidity and Mortality Weekly Report, involved 13 people in Kansas and one in a neighboring state and was initially identified in a hospitalized infant in Kansas in November 2021. Resistance to the four drugs that constitute first-line TB therapy was confirmed by DNA sequencing and drug-susceptibility tests. Investigation by public health officials identified four additional members in the infant's household with MDR-TB.

In January 2022, an infant from a second household in the same apartment complex was hospitalized with TB, and culture-based testing identified the same drug susceptibility pattern as the first household. MDR-TB infection was then detected in the child's mother and four additional household members. Further investigation revealed the families in the two households had extensive social contact and shared a car to commute to the same workplace.

Additional cases were subsequently identified in two households in a different neighborhood that were connected to the first two households, and in a child in a neighboring state who had connections with the second household. Nine cases of latent TB infection were also identified in the four Kansas households.

Outbreak may have begun with overseas infection

To date, 13 of the 14 individuals with MDR-TB have completed treatment, and one declined treatment. The nine individuals with latent TB have also completed treatment. The patients will be examined every 6 months for more than 2 years after treatment completion.

Investigators say that while identifying a source of the outbreak is difficult, it's plausible that it may have begun with a non–US-born adult in one of the first two households who had been infected overseas and went untreated, leading to further transmission. MDR-TB cases in the United States tend to be detected among non—US-born individuals. Only 77 cases were identified in the United States in 2021.

"This outbreak is also a cautionary tale, reminding other low TB incidence jurisdictions that sustained declines in TB incidence are not assured," they wrote.

Though case reporting doesn't accurately reflect COVID-19 activity because of decreased testing and reporting, the number reported over the past month increased by 63%, with increased cases reported in three regions, the World Health Organization (WHO) said in its latest weekly update yesterday.

During an online Q and A session today, Maria Van Kerkhove, PhD, the WHO's technical lead for COVID, said the latest update is the WHO's final weekly report as it transitions to monthly reporting.

Europe, the Western Pacific, and the Eastern Mediterranean regions all noted rises in infections. No reporting data were available from the Americas. Deaths were up in one region, the Eastern Mediterranean.

Over the past month, only 44% of countries reported any cases to the WHO, a proportion that has been declining since the middle of 2022. Of reporting countries, some of those with upward trends include Iran, Belgium, Ireland, the United Kingdom, and South Korea.

Of the 19 countries that regularly report data on hospitalization for COVID, eight reported increases of 20% or more compared to the previous month: Bangladesh, Ireland, Greece, Kyrgyzstan, the United States, Malta, Mexico, and the Netherlands. Of 17 countries that regularly report intensive care unit admissions, 6 reported increases of 20% or more: Ireland, Malta, Singapore, Latvia, Greece, and the Netherlands.

The WHO's variant tracking shows that XBB.1.16 and EG.5 are the most common variants of interest, and EG.5 is the only one showing an increase. The agency said the potential impact of BA.2.86 mutations is currently undergoing careful assessment, and so far no deaths have been reported in any patients infected with the variant.