Leprosy and One Health

​A key theme of my research is understanding leprosy transmission within a One Health framework.

Leprosy in animal hosts
Leprosy is an age-old disease that is rare in the U.S. but remains highly endemic among developing countries of the world. Traditionally thought to be an exclusively human disease, leprosy has also been observed in wild armadillos, red squirrels, and nonhuman primates. Most cases of leprosy in humans are caused by the bacterium, Mycobacterium leprae, although some cases are also caused by Mycobacterium lepromatosis.

​As part of my doctoral research, I led the first genomic study of leprosy in captive nonhuman primates (Honap et al. 2018). We sequenced the genomes of M. leprae strains from captive but naturally infected chimpanzee, sooty mangabey, and cynomolgus macaque. We showed that these strains are fairly genetically similar to M. leprae strains found in humans, suggesting that leprosy can be transmitted from humans to nonhuman primates and vice versa.

Subsequent studies by other researchers have also found that wild chimpanzees in certain parts of Africa carry M. leprae. Such findings have important implications for the effective control of leprosy.

Currently, I am working with Dr. Charlotte Avanzi on the genomic surveillance of leprosy-causing pathogens across human and animal hosts, including in ancient populations. 

A chimpanzee with leprosy (Suzuki et al. 2010)

Mycobacterium lepraemurium genome
Another of my doctoral dissertation projects involved studying how the bacterium that causes leprosy in cats and rodents, Mycobacterium lepraemurium, is related to M. leprae (Benjak et al. 2017). We were the first to publish and characterize the genome of this bacterial species. 

We found that these two pathogens, M. leprae and M. lepraemurium, are not closely related at all. Rather, M. lepraemurium is genetically most closely related to M. avium, which causes TB in birds. Another interesting finding of this study was that the genome of M. lepraemurium is slowly evolving towards a state of obligate parasitism, as evinced by the presence of numerous genes which have lost their functionality.

M. lepraemurium genome map (Benjak et al. 2017)