An engineering student was preparing for final exams by staying with a friend on campus during study week. While there he had all his meals on campus and did not venture off campus except on Sunday before finals to go to church. On Tuesday, the second day of exams he was diagnosed with gastroenteritis as he presented with vomiting and severe diarrhoea. The doctor surmised that it could be due to a bacterial toxin/pathogen. Draw a block diagram to illustrate a probable exposure pathway for this bacterial toxin. The diagram must clearly indicate the source, transport mechanism, exposure point, exposure route and the receptor.