Two readers chime in. Also, many have corrected me for calling TB a virus. It ain’t. It’s a large posssum that gets into your garbage. Oh, no wait. It’s a bacterium. Sorry. Anyway, it seems like it was mostly just bad writing, which is what I suspected:
I’m so happy to see a post I can definitely respond to, as I am an immunology
graduate student (obviously not working too hard today).
The story is indeed poorly written, not politically correct. It basically
fails to explain at a base level an effect we call “the Hygiene Hypothesis”.
This follows that people who spend the first ten years of their lives near the
equator develop different immune systems than those in higher latitudes.
Importantly, they are exposed to intestinal parasites, which initiates a type
of immune response called TH2. TH1 responses are generally directed towards
intracellular pathogens like viruses. The problem is, the absence of TH2
responses in people in northern latitudes tends to correlate with development
of all sorts of nasty autoimmune diseases (MS, diabetes, etc), pretty much as a
result of an imbalance of immunity. This is good for people near the equator
as far as autoimmunity goes, but may be detrimental when giving them vaccines
that have been tested on us northern TH1 people. I’m not convinced however,
that trying to limit their TH2 responses, which is what being proposed by the
vaccine researchers, is a good idea…
I hope this clears up that almost nonsensical article.
Keep up the good work.
My institution doesn’t have an online subscription to the actual journal, so I can’t read the article for myself, but I think a priori you can rule out the possibility that the article is glossing over something to do with race. After all, people living near the equator include all sorts of races — just not, primarily, Caucasians. My guess is that it has to do with parasites, which are MUCH more common in the tropics (and oh so cool and gross). So if a Swede moves to Indonesia, and lives there long enough that his immune system becomes adapted to parasites (i.e. more active TH1 cells, is my inference), probably he will “go local” in terms of response to the TB vaccine — certainly that would be true of a Swedish infant raised there.