Bill Gates and his charities are mostly dedicated to creating change in the United States. Still, the billionaire hasn't forgotten about issues at the global level. His latest call for action relates to fighting the world's tropical diseases, the Guardian reported.

Gates compares the myriad of today's deadly tropical diseases to AIDs or something similarly catastrophic and headline-grabbing. If such diseases were thought of as one large group -- like how Gates frames them in his interview with the Guardian -- they would receive the attention (and funding) they deserve. One in six people worldwide are at risk for tropical disease.

"If this was one disease and the entire burden was attributed to one disease, it would be right up there with the big diseases," he told the Guardian. "As a group ... the human burden [in terms of disability] is pretty gigantic. I put this whole program up there with what's going on with malaria, what's going on with TB, what's going on with HIV - it's something that people ought to be pretty excited about the progress that's been made."

Rather than simply bring attention to the problem, Gates has been working on its solution since at least 2012. In January of that year, he convened the CEOs of the world's largest drug companies -- a meeting only few people in the world could have organized, given the heads of drug companies are typically more rivals than allies, according to the Guardian. There, they signed a declaration pledging to do whatever possible to fight the world's tropical diseases.

Recently, Gates met with the same group in Paris to track their progress. In addition to raising a significant amount of money, the coalition's most impressive accomplishment was developing a diagnostic test and early-stage pill for sleeping sickness (African trypanosomiasis), contracted by the bite of a fly and deadly without treatment.

"We're super-happy with what they've done on two fronts - the drug donation front, where they're ramping up the capacity and helping with the logistics, to get this stuff delivered, and the second is on the diagnostic and drug front to look at where we still have gaps.

"The best news story we have here is that we have a new diagnostic for sleeping sickness and we have a drug that, although it's in a phase 2 [trial], looks pretty promising as an oral treatment for this."