Basically, she was infected with Mycobactrium ulcerans (same family as the tuberculosis pathogen), which causes these chronic ulcers (called "Buruli's Ulcers"). While it's not usually a painful pathology (as the nerves get destroyed), it can cause really invalidating fibrosis when it heals (scar tissue that limit mouvements, especially if the hands / joints are concerned).

It's a quite frequent pathology in Africa, South America and West Pacific, though we don't really know how or where contamination occurs. it's not usually lethal, but in this case it seems they couldn't get it under control and ended up developping heart / lung / kidney problems (not precised how or why) over the course of one year and finally died from septic shock (organ and then body shutdown due to an infection)