In response to the last post we got a super-insightful comment from “Jeff”:



“The level of Lyme disease diagnosis is more than anything, proportional to the publicity and near hysteria generated by shows like Dr Oz and Oprah.”



I know Oprah is powerful, but does she really have mind control over Maine’s physicians and the CDC? How did she muster the “publicity and near hysteria” for other tick-borne diseases like anaplasmosis and babesiosis?



Not to be undone, Jeff tried again:



You certainly cherry picked Maine.

Some neighbour states to Maine (about the same latitude) have Lyme disease notifications falling over the decade.

New York 2006 = 4460 , 2016 = 2623 (confirmed) + 1259 (probable) = 3882

New Hampshire 2006 = 617, 2015 = 436

And southern Texas increases 29 to 71 over the decade



Don’t they get the “Oprah” show in New York and New Hampshire? The horror …

Lest others miss the point, let me make it explicit. Global warming is changing where diseases (like Lyme disease) are common, by changing where disease vectors (like ticks) are common. Lyme disease has been with us quite a while, but only recently has it been common in Maine. The reason? Global warming.

But wait — didn’t I suggest it was temperature increase (specifically, overnight low temperatures in winter) that brought this about? Aren’t New York and New Hampshire at about the same latitude? Haven’t they also seen increases in overnight low temperatures in winter? Yes, yes, and yes. Then why, oh why, haven’t they also shown dramatic increases in Lyme disease?

Maybe … just maybe … it’s because they were already warm enough (even overnight during winter) to sustain a tick population (specifically, the deer tick which transmits Lyme disease) and the hosts on which they prey. Perhaps … perchance … Maine wasn’t … but now is.

Shall we investigate? Here’s the average overnight low temperature during winter in New York, New Hampshire, and Maine:

It looks like Maine is colder than New York and New Hampshire, at least on average during winter nights. This, despite its being at about the same latitude. Funny that.

Temperature in Maine has crossed a threshold, the one which has allowed the tick population to explode. The frequency of Lyme disease (and other tick-borne diseases) has exploded right along with it.

As for Texas, I think that’s Jeff’s attempt to suggest that you can get a dramatic rise in Lyme disease without global warming. Maybe you can — but not if you go by Texas. Lest anyone think the “increase” in Texas is a worrisome trend like it is in Maine, here’s the data (which Jeff used) for Texas, showing those fluctuations from year to year that we all expect.

But it doesn’t show any trend unless the blue dashed line is your idea of a trend, Jeff. My idea of a good way to estimate a trend is the red dashed line, from least-squares regression. But don’t rejoice too soon, Texans, it’s not statistically significant. For all we know, Texas’ Lyme disease cases are fluctuating but don’t show any trend at all.

Just to refresh everyone’s memory, this is what a trend looks like:

Do I really have to do least squares (or other type of) regression and quote a test statistic?

Maine gives us an excellent example of the spread of disease brought about by climate change. That was the point, lest anyone miss it. Lyme is just one disease, from one disease vector, in one state. Don’t doubt that there are others.

Which diseases are coming for your state?

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