Floyd Hammer and Kathy Hamilton of Union could never have guessed that a construction trip to Tanzania in 2003 would permanently change their lives.

The married couple went to the East African country 10 years ago to help renovate what was then a leprosy hospital into an AIDS clinic. "My last name is Hammer, and I’ve always abeen in construction!" laughs Floyd, who is also a retired farmer and Farm Bureau member. "Some friends who were doctors asked us to go and supervise this project."

What the couple found there were children dying from hunger and related diseases. At the same time,...