Na-GST-1 is a protein expressed during the adult stage of the hookworm life cycle that is thought to play a role in the parasite's degradation of host hemoglobin for use as an energy source. Vaccination with recombinant GST-1 has protected dogs and hamsters from infection in challenge studies. This study will evaluate the safety and immunogenicity of two formulations of Na-GST-1 in healthy adult volunteers when co-administered with the immunostimulant CpG 10104, a Toll-like Receptor-9 agonist.