Armadillos and Leprosy

Armadillos and Leprosy (June 25, 2013)

In my book, ‘Dillos, I explained some of the history of leprosy research and the findings in Louisiana that some dillos carried the leprosy bacterium. This bacterium is related genetically to tuberculosis. The leprosy organisms has been hard to study because it is almost impossible to grow in tissue culture. The issue¬† all along has been whether armadillos get infected with leprosy from humans (the organism is found in soil and dillos are notorious for grubbing around in dirt). In 2011, Richard Truman in a government lab in Baton Rouge, reported that 65% of human lepers had leprosy organisms that were genetically identical to those found in ‘dillos, suggesting strongly that humans got the disease from handling dillos. Historically this does not make sense, because human leprosy originated in the Middle East (probably Iran and Turkey), where there are no dillos, nor have there ever been.

Now, the picture is clearer, based on new genetics research on a heavily infected 700-year old human tooth in Denmark from a woman who died in a leper colony. Using techniques that researchers recently developed for ferreting out the DNA of the tuberculosis organism from old bones, the researchers isolated enough of the leprosy DNA to sequence it. The genes in that human DNA are essentially the same as those found in modern-day leprosy, showing that this organism has evolved slowly. More relevant to the dillo transmission issue, the DNA sequences in this human sample are strikingly similar to that of strains found in dillos. This makes it likely that originally, dillos caught leprosy from humans. Clearly, transmission of the disease can go in both directions.

Source: Gibbons , Ann (2013). On the trail of ancient killers. Science 340: 1278-1282.

Updated: August 18, 2014 — 8:33 pm
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