@Idaho_Cowboy Interesting stuff--I finally got to the website and checked out the Forbes article, then I followed it to the Science link, read the abstract only (I'm not a subscriber), and listened to the videos that led to.
Part of the research led to postulation that microbial makeup affects the efficiency with which we digest our food. Those with the more efficient assemblages of bacteria in our intestinal fauna will extract more calories from a given amount of food than those with less efficient intestinal flora. Now, that makes sense to me, given all other things being equal, some people can eat like they have a herd of pet tapeworms and not gain an ounce, while others look at a food magazine and put on ten pounds.
On the flip side,
Toxoplasmosis, for one, (caused by
Toxoplasma Gondii) is a well documented parasitic infection in humans
http://www.cdc.gov/parasites/toxoplasmosis/gen_info/faqs.html.
Effects vary from flu like symptoms to "symptoms that include fever, confusion, headache, seizures, nausea, and poor coordination" in more severe cases (usually imunocompromised people, such as those with HIV), and occular symptoms as well, including
"Eye disease (most frequently retinochoroiditis) from Toxoplasma infection can result from congenital infection or infection after birth by any of the modes of transmission discussed on the epidemiology and risk factors page. Eye lesions from congenital infection are often not identified at birth but occur in 20-80% of infected persons by adulthood. However, in the U.S. <2% of persons infected after birth develop eye lesions. Eye infection leads to an acute inflammatory lesion of the retina, which resolves leaving retinochoroidal scarring. Symptoms of acute disease include
eye pain
sensitivity to light (photophobia)
tearing of the eyes
blurred vision
The eye disease can reactivate months or years later, each time causing more damage to the retina. If the central structures of the retina are involved there will be a progressive loss of vision that can lead to blindness.
Which makes me wonder if Hillary ever had a cat...or a (nevermind, ask Huma).
At any rate, yes, apparently we have just begun to touch the surface of the interrelationships between humans and our bacterial pets/pests, and in some cases, we need the little critters to function as we should.