I'm trying to identify a story - I think it was novella, not a short story, but I'm not sure - about people who survived when a disease wiped out most of Earth's population.
If I recall correctly, the surviving people were living in domes, because the disease was still in the air. Some people were resistant to the disease, because of some difference in their DNA - I seem to recall it being described as "backwards".
These people with the "backwards" DNA then leave the domes - I don't remember why - ending up in Egypt, I think. Around this point in the story I remember the disease being described as acting so quickly that you could get a headache, lie down for a rest, and a couple hours later be nothing but dust.
I read this in the past two years, but I think it was older than that. If I recall correctly, it was in an anthology of selected stories - the year 1995 comes to mind. It was not a tall book, and I think the cover was dark. IIRC, it was a collection of stories by different authors.