Francesca Tomasi received her B.A. from the University of Chicago and now does microbiology research.
Tuberculosis is a leading global infectious killer, and it has been since the dawn of humanity. Infective Perspective’s Story of Tuberculosis outlines the history of this deadly bacterium, and our story about today’s quest for global eradication sheds a light on TB’s future. Most present-day efforts against tuberculosis revolve around the fact that the disease is predominantly respiratory: it is transmitted in the air (through coughing, sneezing, and other aerosolized fomites); over 80% of infections occur in the lungs.
Earlier this week, researchers published a new finding: an emerging strain of tuberculosis has evolved a cunning method of transmission in mongooses that gives a new face to the term “fecal-oral.” This strain, called Mycobacterium mungi, is a member of the Mycobacterium tuberculosis complex and was discovered in Northern Botswana. It spreads between mongooses via nasal planum exposure to anal gland secretions, also known as the mongoose method of communication.
Animals mark their territories by urinating, thereby also secreting other kinds of substances. In the case of M. mungi-infected mongooses, their anal gland secretions leave the bacteria in a protective oily coating, where they can survive in nature (for how long, we’re not quite sure yet). The paramount notion of territoriality in nature ensures that other mongooses will come sniffing around. Any animal with a minor scrape or cut on its snout – the nasal planum – provides a point of entry for the bacteria. Advanced disease infiltrates and damages the lungs the way human tuberculosis does, eventually killing the infected animal.
This newly-identified mechanism for TB transmission has potentially serious implications: livestock tuberculosis is a very real concern both for wildlife and humans. Researchers now have another physiological route to look for TB while investigating outbreaks. Humans communicate by talking, and those with tuberculosis generate aerosolized bacteria when they do anything that produces spit. Many animals communicate instead by marking their territories through urination, and now a new strain of TB has been shown to spread by this system. Tuberculosis is quite the social disease.