I'm looking for a short story/novella about a plague through genetics that infects the world

Question

I only read it this year but I think it could have been written in the last 4 or 5 years. It's seen through two different time periods. One is the far past where an explorer or maybe a missionary is staying with these tribal/primitive people that live in Nepal? Or some far off region. Although it is two tribes they are separated by blood lines. One wears a yellow belt and the other blue and depending on which belt color you have you can only marry and procreate within your color or else the natives feel a demon will be released.

Then in the future, there is a plague and two scientists search for the clues even using the historical documents to find patient zero who had cross-bred with the opposite belt people. It is only after the wife loses her husband and child and many years later that she finds the cure.

Answer 1

I found it. It was called Mara's Shadow by Darci Stone in the Writers of the Future Volume 34 anthology.

The science behind the story forms around a group of scientists working on solving an unknown disease. The facts don’t seem to add correctly with everything they know. As more and more people contract symptoms, it becomes evident that the disease is becoming a plague. Ngo Lien, one of the primary scientist is searching for the point of origin of the disease to try to learn how it spread. She becomes more motivated as she watches more people dying. Can she save humanity?