The bacteria may have multiplied in either the water, if it was polluted, or in the oysters during storage. If the starting number was one cell of Vibrio, how many doublings (or generations) does the cell have to go through to get to 1 million? (Remember, 1 million is the infective dose).
Here’s a likely but vague answer: probably not as many as you think. Let’s try some numbers. You can play along at home using a calculator, or just click the buttons to see the answer:
10 generations: 210
15 generations: 215
20 generations: 220
The magic number is 1 million, and although the number is well below this after 15 generations, after 20 generations, the numbers have reached the million mark.