

Increasing marker number did not change accuracy for differentiation and diversity but did improve precision. There were no a priori characteristics that could predict the performance of markers in natural infections based on their performance with laboratory strains.

Using a set of 25 microsatellites, we calculated allele frequency profiles of eggs in fecal samples from people in two Brazilian communities separated by 6 km: Jenipapo ( n = 80) and Volta do Rio ( n = 38). Those infected by Schistosoma mansoni carry many genetically distinct, sexually reproducing parasites, therefore, for an individual infection the complete allele frequency profile of their progeny consists of a pool of DNA from multiple diploid eggs. Individual markers had 5–13 alleles, allelic richness of 2–10 and an effective allele number of 1.3–8.14. On laboratory strains their heterozygosity ranged from 0.22 to 0.77.

These microsatellites were distributed across all seven autosomal chromosomes. Of these, 27 were unique, autosomal, polymorphic, easily scored and single copy as assessed on pooled adult worm DNA from two different continental origins and adult worm clones. All 52 were evaluated for autosomal location, strength of amplification, scorability and behavior as single-copy loci by polyacrylamide and capillary gel electrophoresis. All Schistosoma mansoni tri- and tetranucleotide repeat microsatellites published as of December 2018 were identified.
