Guns Germs & Steal is a decent read. Reading about & studying health stuff. Spending a lot of time browsing health groups & forums around dietary advice & other things. Paying attention to gardening & permaculture stuff. The same patterns are everywhere. The names for "diseases" people get are mostly just bullshit that someone made up. There are a handful of things that happen when people get sick. There are a handful of things that happen when plants get sick. The root causes have more to do with some sort of damage or deficiency that makes the infection possible.

For example, it seems pretty clear that Polio was the result of lead arsenic pesticide poisoning which permeated the gut lining & damaged lots of body tissue near the intestines, the most important tissue being the spinal cord. Damage to the spinal cord in the gut region makes them unable to walk. When something passes through gut tissue (creates leaky gut conditions) it can shuttle in all sorts of pathogens that are almost always present & would otherwise be harmless. So the problem isn't the pathogen it's the substance that granted the pathogen access to parts of you where they can do harm. But blaming the pathogen allows pesticide companies to escape liability & pharama corps to sell a new treatment.