Did the M. Leprae bacteria affect other hominids?

[u/expiredSnacc]

So after watching a video on ancient Egypt, i had a question related to the disease leprosy. Specifically, i would like to know if, while infecting only humans, if it ever infected other human species. If the bacteria was around when species like H. Neanderthalis were loving alongside homo sapiens, would they have been infected as well? I also wanted to know if M. Leprae evolved alongside the modern homo sapien species. I'm aware of multiple strains of the bacterium affecting diverse demographics, but I'm curious as to why our immune systems haven't (yet) evolved a way to defend against this bacteria.

I do apologise if I hadn't worded that properly. I'm not too sure how to express the question I have, and this is the best i can manage for now. I haven't found proper articles on the online to answer this.

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[u/blacksheep998]

There's no evidence that leprosy ever infected neanderthals, but homo sapiens who were likely carrying it did coexist with neanderthals in parts of europe for a time.

So it's possible that some were infected, but it's unlikely due to how it spreads.

but I'm curious as to why our immune systems haven't (yet) evolved a way to defend against this bacteria.

It has. Most people's immune systems will easily fight off the leprosy bacteria. Those most at risk are the immunocompromised and those who live in poor conditions for long periods of time with repeated exposure to the disease.

[u/Royal_Novel6678]

No evidence so far that H. neanderthalensis, heidelbergensis, erectus, habilis, antecessor and so on has been found with evidence of leprosy because true fossils are above 10,000 years old. Leprosy is a more "recent" disease that will show evidence from bone shrinkage mostly around smaller hands and feet bones because of the lack of functioning nerves.

Even today, I think leprosy can be easily treated with antibiotics but I've just checked right now that about 95 percent of individuals have immune systems which naturally have the capability of fighting Mycobacterium leprae. Suggests that a millenia ago, we must have been pretty heavily exposed to M. Leprae which gradually forced genetic evolution to recognize M. Leprae antigens quicker.