we've wiped out or drastically reduced most of the diseases that cause severe, attributable death and disability
we've wiped out or drastically reduced some diseases in some parts of the world. There's a lot of infectious diseases still out there: HIV, influenza, malaria, tuberculosis, cholera, ebola, infectious forms of pneumonia, diarrhoea, hepatitis ....
we've connected the world with high-speed transport links, so that the subtle, minor diseases can spread further.
Disease has always spread - wherever people go, far and wide. It just took longer over land and sea (rather than the nodes appearing on global maps that we can see these days).
... very likely for autoimmune conditions ... have risen greatly over time
"autoimmune conditions" covers a long list of conditions lumped together because they involve the immune system 'going wrong'. (and the immune system is, at least to me, a mind-bogglingly complex system)
Given the wide range of conditions that could be "auto-immune" saying they've risen greatly over time is vague. Data for more specific conditions?
Increased rates of automimmune conditions could just be due to the increase in the recognition, diagnosis and recording of cases (I don't think so but it should be considered).
What things other than high speed travel have also changed in that time-frame that could affect our immune systems? The quality of air we breathe, the food we eat, the water we drink, our environment, levels of exposure to fauna and flora, exposure to chemicals, pollutants ...? Air travel is just one factor.
I think this is somewhat likely for chronic fatigue and depression, including subclinical varieties that are extremely widespread.
Fatigue and depression are clinical symptoms - they are either present or not (to what degree - mild/severe is another matter) so sub-clinical is poor terminology here. Sub-clinical disease has no recognisable clinical findings - undiagnosed/unrecognised would be closer. But I agree there is widespread issues with health and well-being these days.
Or, put another way: the "hygiene hypothesis" is the opposite of true.
Opposite of true? Are you saying you believe the "hygiene hypothesis" is false?
In which case, that's a big leap from your reasoning above.
This post is a container for my short-form writing. See this post for meta-level discussion about shortform as an upcoming site feature.