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1 kirkspencer  Mon, Mar 31, 2014 8:20:29am

Not new news. Bubonic plague can be spread by multiple vectors: airborne (coughing from an infected individual) and fleas. It’s also not new news that people of the time lived in less healthy conditions. Nor is it new news that the poor were generally less healthy than the wealthy.

It’s annoying that Dr. Brooks - or the Guardian’s editing of his remarks - seem to imply all the above is new, and further that the plague was transmitted solely by airborne vector.

2 steve_davis  Mon, Mar 31, 2014 8:58:41am

Yep. My understanding was always that bubonic plague had a component that allowed it to be spread via air, once it had established itself in a person. I seem to recall that getting infected from a flea was actually a good thing, because you had SOME chance of survival, whereas lethality of the airborne form was pretty much not only fatal, but fatal within hours of exposure.

3 CriticalDragon1177  Mon, Mar 31, 2014 9:44:49am

re: #1 kirkspencer

re: #2 steve_davis

Well I hadn’t heard about the virus spreading via the air before.

4 steve_davis  Mon, Mar 31, 2014 1:47:53pm

re: #3 CriticalDragon1177

Well I hadn’t heard about the virus spreading via the air before.

yeah, it’s a little confusing because this doctor does make it sound like this is some revelatory thing, but as I say, I think the BUBONIC plague was the one with the black nodules that formed in the lymph nodes, but that once somebody was infected, they could then become a vehicle for the spread of PNEUMONIC plague, which was airborne and way more deadly.

5 Flounder  Tue, Apr 1, 2014 2:07:50pm

I’m a survivor of the plague, how do I know this? I have a hereditary disease called hemochromatosis, inherited from eastern European descendants.

The iron-poor macrophage essentially starves the intracellular plague bacteria by not providing them with iron. This is a happy accident for us, but it isn’t as if the macrophage doesn’t already know this trick. Iron can be an important immune weapon. In mycobacterial infections (that cause pneumonia), macrophages actually raise the iron concentration in the ingested bacteria and kill them that way. In other infections, macrophages sequester their iron and starve the organisms.

Macrophage iron manipulation is not a natural immune response to Y. pestis, but HH helps to bring about the same effect, and this makes HH valuable. It is believed that many survivors of the plague in the 12th through 15th centuries had hemochromatosis. What is more, the gene is present in as many as 1/3 of living people of European descent, meaning that HH is probably massively underdiagnosed. It is likely that you know someone with HH, whether they not it or not.

Natural selection kept this mutation in the gene pool because it presented a reproductive advantage in times of plague.

biologicalexceptions.blogspot.com

6 John Vreeland  Wed, Apr 2, 2014 9:09:03am

re: #5 Flounder

Hemochromatosis is an excess of iron. The block quote seemed to imply the opposite.

It’s an interesting disease. It mainly destroys the liver, but can be easily managed with monthly blood donations.

I think we will see more cases of this showing up in the future, as women who regularly menstruate are protected, but now with the use of Yaz and other drugs to reduce the monthly cycle we will see more cases of excess iron retention in women.

7 John Vreeland  Wed, Apr 2, 2014 9:10:06am

Oh, and the connection to Y. pestis is interesting. Ididnotknowthat.
Technically, your genes for that trait are likely plague survivors. For all you know the rest of your genes could be from anywhere.

8 Cardio (formerly JRCMYP)  Thu, Apr 3, 2014 7:54:00am

Yes, the airborne nature of the plague has long been known. I remember studying this very fact in 1988 while still in college. If I remember correctly, the death rates were higher during summer and fall when the pneumonic features where higher because transmission was much more rapid.

I saw this article elsewhere CD and thought “huh? didn’t we already know this?” My suspicion is that they’ve found stronger evidence for pneumonic plague during other seasons (besides summer/fall), and in higher populations of the dead, hence the confusion with the “real cause.”

9 dr. luba  Fri, Apr 4, 2014 8:03:35am

The article is poorly written and confusing. There has been disagreement over the years as to whether the Black Death was caused by bubonic plague (Yersinia pestis). Having DNA proof settles that argument. (“Plagues” were common, and many of the symptoms of bubonic plague are non-specific. Not all “plagues” were bubonic.)

I learned many, many years ago in medical school that Y. pestis is initially spread via infected fleas, but, once established in humans, is further (and more efficiently) spread by the pneumonic route. Wikipedia has this to say:

“Pneumonic plague, a severe type of lung infection, is one of three main forms of plague, all of which are caused by the bacterium Yersinia pestis. It is more virulent and rare than bubonic plague. The difference between the versions of plague is simply the location of the infection in the body; the bubonic plague is an infection of the lymphatic system, the pneumonic plague is an infection of the respiratory system, and the septicaemic plague is an infection in the blood stream.

“Typically, pneumonic form is due to a spread from infection of an initial bubonic form. Primary pneumonic plague results from inhalation of fine infective droplets and can be transmitted from human to human without involvement of fleas or animals. Untreated pneumonic plague has a very high fatality rate.”

10 John Vreeland  Fri, Apr 4, 2014 12:09:35pm

I could go farther and say that “normally” the Yersinia pestis bacillus is not troublesome but happily parisitizes fleas with few symptoms. Occasionally, however, the bacillus mutates into a clumping mode that blocks the flea’s gut, preventing it from digesting and causing it to vomit back into its host’s skin capillaries, where it gets picked up by macrophages and infects the lymphatic system. This is what kills the rats, but the starving fleas, desperate for any source of food, will bite any warm-blooded creature they can find. This is a classic example of virulence appearing in a complex way from a single mutation in a pathogen.

Systemic plague will kill you very quickly, but is rare. The bacillus must be introduced into the main blood stream, and infected flea bites tend not to do that. But it apparently happened from time to time as a healthy person came to visit a dying friend and never got up from the bed side.


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