I'm not sure I understand your question -- I do not see how the part about farmers transmitting more germs connects to the rest of the question.
In Chapter 11, Diamond is moving on to a new aspect of his argument. Earlier, he has talked about how important germs were to the European conquest of the New World. Then he talked about how and why Europeans were able to have agriculture first. So -- before Chapter 11 he has concluded that germs were important and he has concluded that Europeans got agriculture and domesticated animals first.
So now in Chapter 11 he is going to talk about how having agriculture and domesticated animals led to Europeans having more germs. He's going to connect up the two ideas -- agriculture and germs.
Is that what you're asking? Let me know...
Farmers tend to live in larger and denser groups as compared to hunter gatherers, because of this epidemics or crowd disease are more likely to affect farmers groups rather than hunter gatherer groups. The epidemics in small groups die out completely very quickly, but in large and dense groups the epidemics spreads from one location to another.
In the past, frequent changes of camp by hunter gatherers meant that they left behind the means of infection such as their own faces and contaminated water. In comparison, farmers who lived in the same location remained near the sources of infection. Also they often used their own faces and urine as fertilizer for farming. The large number of domesticated animals kept by farmers also provided condition conducive to fast spread of crowd diseases among farmer groups.
I would like to clarify that the actual question is: Farmers transmit more powerful germs than hunter-gatherers: Diamond, in this chapter, draws on conclusions that he made in the previous sections. What are they? Do you find him persuasive?
Due to the 150 character limit i had to shorten this to where it mad no sense. It should now be much easier to answer this.