I knew the name of the disease before I started the search, but since you asked for search-fu, I'll mention that I Googled "snail fatal disease," which led to a Wikipedia article[1] and searching the article page for the word "snail" led to the specific section about the disease. The disease name, "schistosomiasis," is of course an even better search term for finding out more information about the disease.
AFTER EDIT: using the same word string from your question here, "how freshwater snails kill humans" (NOT searching as a phrase, but as a string of words) on Google does indeed first bring up the Bill Gates blog post, but a few results below the search results show a World Health Organization document on freshwater snails[2] that largely answers the question.
AFTER EDIT: using the same word string from your question here, "how freshwater snails kill humans" (NOT searching as a phrase, but as a string of words) on Google does indeed first bring up the Bill Gates blog post, but a few results below the search results show a World Health Organization document on freshwater snails[2] that largely answers the question.
[1] https://en.wikipedia.org/wiki/Neglected_tropical_diseases#Sc...
[2] http://www.who.int/water_sanitation_health/resources/vector3...