A primary bacterial infectious disease that results_in infection located_in skin or located_in subcutaneous tissue, has_material_basis_in Mycobacterium ulcerans, which could be transmitted_by insects. The bacterium produces a toxin, named mycolactone, which causes subcutaneous fat necrosis and inhibits an immune response. The infection has_symptom nodule, which is a painless, mobile swelling in the skin.