After the macrophage fails the Helper T Cell stimulates the B cells (create antibodies) if pathogen is extracellular and Cytotoxic T Cells (killer T cells, release perforin) if pathogen is intracellular. Once the pathogen is killed the B Cells create Memory B Cells and the Killer T Cells create memory T Cells.
To try and help although thee aren't any answers i would say... if they were to literally conduct a field study such as this, much pollution would occur, Millions of fish would die as of plants also. And would over-all Lake Michigan would never be the same again.