Ten M. ulcerans strains grown on LJ slants were harvested and DNA was extracted as previously described [35] . Serial dilutions of purified M. ulcerans DNA containing 300,000, 30,000, 300, 30 and 3 copies of IS2404 element per 5 ml were prepared. The number of copies of the insertion sequence element was determined based on the genome size of 5,806 kb and presence of an average number of 207 copies of IS2404. This was used to determine the detection limit of the LAMP assays.