According to Guns, Germs, and Steel, why did Eurasians have an advantage when it came to germs?

The answer to this, like most of the answers in Guns, Germs, and Steel, has to do with geographical advantages.  The Eurasians had better geographic luck.  Their luck gave them many domesticated animals that lived in close proximity to them.  The infectious diseases that the Eurasians carried came from those animals.

The Eurasians carried the germs for infectious diseases where Native Americans and other people did not.  This was because the Eurasians lived very...

The answer to this, like most of the answers in Guns, Germs, and Steel, has to do with geographical advantages.  The Eurasians had better geographic luck.  Their luck gave them many domesticated animals that lived in close proximity to them.  The infectious diseases that the Eurasians carried came from those animals.

The Eurasians carried the germs for infectious diseases where Native Americans and other people did not.  This was because the Eurasians lived very close to their domesticated animals.  Germs from the animals would pass to the people and eventually become infectious diseases.  Table 11.1 on p. 207 shows us a number of infectious diseases that started out in domesticated animals and passed to people.  The Eurasians carried these germs, but did not all die from them because they had gradually developed some resistance to those diseases.  The people of other regions had not developed immunity and tended to die of the diseases in huge numbers.

So why did the Eurasians have domesticated animals while others did not?  Here, the answer is geographic luck.  In Chapter 9, Diamond discusses the fact that most of the kinds of large animals that exist in the world have proven to be unsuitable for domestication.  Table 9.1, on pp. 160-1, shows us that only one of the 14 most important large domesticated animals was native to a place other than Eurasia.  Because of this, people from other regions of the world could not live in close proximity to domesticated animals and could therefore not develop the kinds of germs that the Eurasians carried.  This is why the Eurasians had an advantage over others when it came to germs.