Abstract: A protein, Ancylostoma Secreted Protein (ASP), that is released by hookworm larvae following infection, and which is highly immunogenic in experimental animals, is disclosed. Nucleic acids encoding ASP, antibodies recognizing ASP, and methods of detecting ASP, nucleic acids encoding ASP, and antibodies recognizing ASP, in a sample are also disclosed. ASP is useful in a vaccine for hookworm as well as other soil-transmitted human and veterinary nematodiases. ASP is also useful as a target for specific treatment of hookworm, and can be used in a diagnostic assay for hookworm, using standard protein detection techniques, especially those based on antibodies. DNA encoding ASP is useful both for producing ASP recombinantly and in a diagnostic assay for hookworm. Antibodies recognizing ASP are useful in diagnostic assays to detect protein produced during hookworm infection.