'Unsung Heroes of Humanity' 

Editor:

Read you article this morning and have to agree with you that the development of the smallpox vaccine was one of the major accomplishments for human health ... in fact,  all the developers of our vaccines are really the unsung heroes of humanity ("When the Old World Met the New," Aug. 26).

As you know from reading Doug Preston's book, around 60 percent of of everyone on our expedition developed symptoms of a horrific disease called mucocutaneous leishmaniasis, for which there no real cure yet. Fortunately, most were treated (and some still are since 2015) by the NIH. The researchers there feel we were all infected (since it is spread by sand fly bites of which we all had many) but for some unknown reason, a number of us remain asymptomatic with absolutely no known ramifications. Others essentially have it for life with recurring flare-ups that have fortunately been reduced by their treatments. Why were some of us essentially immune and others not? Probably random genetic and/or immune histories of our predecessors.

In our present pandemic, it is good for people to think about all this and to be thankful for the development of vaccines.

Steve Elkins, Pasadena