This is a cool idea, I upvoted (from -1 to 0). I'd really like to see more detailed analysis and well-documented sources to answer this question. I couldn't really tell from the post whether the numbers were about right or not. 

I worked on a report with others at Longview. We calculated that severely reducing the burden of HIV, Malaria and Tuberculosis would be around  $219 billion. Essentially, we adjusted numbers from a variety of reports from e.g. the WHO to estimate these numbers (possibly some of the same sources, it's hard to tell). This is already quite a bit more than the $10 billion estimate you have. I think the main difference is due to adjusting for inflation and in-kind medicine donations.

However, this wouldn't allow us to eradicate these diseases in all likelihood. In fact, the target for Tuberculosis was to reduce deaths by about 90%. It is plausible that the last 10% is actually much more expensive to target, because the low hanging fruit has been picked, so to speak. (I'm not an expert in this area, and this could be completely wrong).

This makes me think that the cost of eliminating these diseases is likely well over $100 billion each. 

(We also estimated the costs of severely reducing the burden of disease from neglected tropical diseases, and that was lower per disease.)
 

Thanks for this interesting stuff! I like that stat about 10% of diseases causing over 50% of the morbidity/mortality, and eradicating those having a much smaller cost. For that reason me that 1.4 trillion number to potentailly eradicate 50% of the might be more important than the 14 trilllion one.

I'll have a look at the lancet paper - I don't really understand the 8.5 billion being needed to "maintain" the situation after malaria is eradicated, I thought the definition of eradication was that it was gone (like smallpox) - so would no longer need money pumped into it. Perhaps they are assuming malaria remains in animals continuing the life cycle?

Why are you ballparking $10b when all of the examples given are many multiples of that? $100b seems like a better estimate.

I also suspect we're targeting easy to eradicate diseases. Those without animal reservoirs that will cause resurgences and where there are effective interventions. Therefore, I'd suggest this is a lower bound.