TB Transmission: How Does the Body’s Response to Different Strains Potentially Affect Spread of Disease?

A pair of strains of the bacterium that causes tuberculosis has only minor genetic variances, although it attacks the lungs differently, researchers of a study said.

A EurekAlert! report specified that the findings of this research could help break the cycle of rapid transmission of tuberculosis, the second-leading infectious killer globally after COVID-19, according to the World Health Organization.

The disease mechanisms unveiled in the research could also offer answers about why treatments are effective in some patients while inefficient in others.

According to associate director of the Public Health Research Institute at Rutgers New Jersey Medical School Padmini Salgame, such findings implicate strain differences as having an important impact on the response of lung alveolar macrophages and the manner tuberculosis manifests itself in the body, and how it is transmitted.

He added that they believe, too, that it will inform any individual who hopes to "diverse more effective treatments."

Impact of Mycobacterium Tuberculosis on the Lungs

To understand transmission further and how it relates to treatment results, the researchers focused on the impact of the said two strains of Mycobacterium tuberculosis on the lungs.

Even though the variants differ slightly in their gene sequences, one is considered "high transmission" as it's spreading easily, while the second is "low transmission" as it is not infecting as readily.

Essentially, TB bacteria are transmitted through the air when those with TB disease in their lungs are coughing, speaking, or even singing.

Through the use of strains identified in a this Rutgers collaborative study published in the Nature Communication journal, with researchers at Nucleo de Doencas Infecciosas in Brazil comparing high and low transmission households of individuals with TB, the scientists examined the immune pathways that the pathogens stimulated in the infected mice's lungs.

'Granulomas'

A similar Odishatv. report specified that in mice infected with the high transmission variant, their lungs rapidly formed clumps of immune cells identified as granulomas that encased the invading bacteria, halting the development of a more virulent disease.

In most circumstances, the granulomas eventually broke down, spilling their contents. Describing their findings, the study investigators believe that if the escaped microbes are close enough to the bronchial airway, they could be released into the air as "infectious aerosols."

Salgame, also a professor in the Department of Medicine, explained that through the introduction of granulomas "with the potential to develop into cavity lesions" that aid microbial escape into the airwaves, high transmission M. tuberculosis variants are poised for greater communicability.

In mouse models infected with the low transmission strain, the invading microbes were slow in activating lung alveolar macrophages and generated patches of inflammation within the lungs that did not enable the bacteria to escape into airways and enabled them to conglomerate and intensify the infection, explained Salgame.

Hope for New Approaches to Stop TB Spread and Treatment

This discovery of the different trajectories taken by the TB strains provides hope for new approaches to halting spread and treatment.

The associate director also said they have long known that some individuals with TB are more infectious than others.

Nonetheless, he added that the mechanisms accountable for this variability in transmission between people with TB had not been well understood until now.

Related information about how the body reacts to tuberculosis is shown on Doctors Without Borders' YouTube video below:

Check out more news and information on Tuberculosis in Science Times.