9 ms·
Black Death 'spread by humans not rats'
- sillysaurus3 9y agoIf you want to get into the mindset of what it was like to deal with the black death, check out Plague Doctors: https://www.youtube.com/watch?v=oDz0OrRZOZ0 https://www.youtube.com/watch?v=oDz0OrRZOZ0
- JumpCrisscross 9y agoOn the upside, Black Death survivorship may explain Europeans' relative resilience to HIV (edit: smallpox) [1]. [1] https://www.nature.com/news/2005/050307/full/news050307-15.html https://www.nature.com/news/2005/050307/full/news050307-15.h...
- IncRnd 9y agoIf the contention of this page's article is true (BD spread by humans), then the link you posted is more in favor of smallpox being the cause of relatively greater resistance to HIV in Europe.
- agumonkey 9y agoCute video. Too bad the costume had a few weak spots, the idea of sealing/isolation is deeply valuable. If it hadn't failed there, it would have helped many other diseases.
- mc32 9y agoSo I guess, one question this would raise, is, of modern infection, what is the vector found? Not that they must be the same, but at least they might have an explanation as to why modern infections would be different from historical ones, if they are any different.
- BorisVSchmid 9y agoThere are some studies that looked at the ectoparasites found during plague outbreaks, but just finding an ectoparasite with plague-infected blood in it doesn't tell you much yet on the importance of the transmission route. Piarroux R, et al. (2013) Plague epidemics and lice, Democratic Republic of the Congo. Emerg Infect Dis 19:505–506. Laudisoit A, et al. (2007) Plague and the human flea, Tanzania. Emerg Infect Dis 13: 687–693. Ratovonjato J, Rajerison M, Rahelinirina S, Boyer S (2014) Yersinia pestis in Pulex irritans fleas during plague outbreak, Madagascar. Emerg Infect Dis 20:1414–1415.
- microcolonel 9y agoThis may mean good things for the outbreaks in remote parts of Madagascar and anywhere else one may occur, because the solution could be as simple as sanitation and delicing.
- BorisVSchmid 9y agoThe 2017 madagascar one might actually have been a combination of rats and pneumonic plague. But yeah, it is good to pay attention to all possible routes of transmission and see where you can intervene.
- toolslive 9y agoI think this was already known in the 90s. At least a plaque in the Antwerp Zoo has already been stating this since the beginning of this millenium.
- BorisVSchmid 9y agoYou are right that there have been people speculating about it for a long time, going back more than a hundred years. Some of the earliest reports are from the time of the Indian Plague Commission, and there have been some snippets of evidence since then. One of the groups that is doing most of the research on body lice as vectors of plague is the group of Didier Raoult. Michelle Ziegler made a nice summary of that work here: https://contagions.wordpress.com/2016/11/17/the-case-for-louse-transmitted-plague/ https://contagions.wordpress.com/2016/11/17/the-case-for-lou...
- nukeop 9y agoDoes this shed a new light on the mystery of why the area of modern Poland was spared, remaining largely unaffected by the plague? Also it makes a certain novel sound a little bit less realistic.
- Angostura 9y agoMaybe 'known' is a bit strong. Surmised, perhaps? This study adds some interesting modeling
- olavk 9y agoIt seems to be an internet myth that Poland was laregly spared. Some guy over at AskHistorians actully dug into the evidence: https://www.reddit.com/r/AskHistorians/comments/79dwua/why_did_poland_have_lower_rates_of_black_death/ https://www.reddit.com/r/AskHistorians/comments/79dwua/why_d... - it is a fascinating writeup.
- BorisVSchmid 9y agoLast author here. The paper itself comes out this week on PNAS, but the press embargo is lifted already. When it comes out, you can find it here: http://www.pnas.org/cgi/doi/10.1073/pnas.1715640115 http://www.pnas.org/cgi/doi/10.1073/pnas.1715640115 What we have done is compare the rise and fall of daily or weekly mortality levels during plague outbreaks against three models of plague transmission - two that are generally accepted (rat-borne plague and pneumonic plague), and one that has been speculated about for a long time (human ectoparasites like body lice and fleas). We allowed the models to achieve the best fit they could within biological parameter constraints, and see how well each of these models could mimic the observed mortality curve. There is a bit more detail in this interview: https://news.nationalgeographic.com/2018/01/rats-plague-black-death-humans-lice-health-science/ https://news.nationalgeographic.com/2018/01/rats-plague-blac... The code/models we used are available online for one of the outbreaks (Barcelona 1490) https://zenodo.org/record/1043924 https://zenodo.org/record/1043924 A pre-review version of the paper is available as a poster here: http://www.mn.uio.no/cees/english/people/phd/katharrd/kd_yersinia_poster.pdf http://www.mn.uio.no/cees/english/people/phd/katharrd/kd_yer... Note that we changed the lice model a bit since then, on recommendation of one of the reviewers.
- raphaelj 9y agoCould it be a combination of several transmission methods? Like rats + lice?
- BorisVSchmid 9y agoThat indeed could be. We didn't test mixed models of transmission, but we took the first step here by testing all three models independently. Xavier Didelot did some work on testing mixed models for two cities, 17th century Eyam and 19th century Cairo. He did have to further simplify the models though - there are some restrictions on how many floating parameters you can have while the models are trying to converge to the parameter set that results in the best match with the observations. Epidemiological analysis of the Eyam plague outbreak of 1665–1666: http://rspb.royalsocietypublishing.org/content/283/1830/20160618 http://rspb.royalsocietypublishing.org/content/283/1830/2016... Model-based analysis of an outbreak of bubonic plague in Cairo in 1801: http://rsif.royalsocietypublishing.org/content/14/131/20170160.article-info http://rsif.royalsocietypublishing.org/content/14/131/201701...
- tw1010 9y agoAttention-grabbing headlines and bad research has conditioned me to not update my beliefs based on anything that I only briefly stumble upon like this. There might have been a time when reading an article like this would blow my mind, and make me excitedly share it with others who had a similar belief, but now my first impulse is to just feel sceptical.
- BorisVSchmid 9y agoNot a bad first impulse :-). It often pays in science to wait a few years/follow-up studies before fully accepting something. What is thought to be true in plague is especially fluid now with ancient DNA studies on human remains coming out regularly, each with its own narrative on how to explain the phylogenetic tree. That said, there are some long-standing questions in plague research, one of which is why the first and second plague pandemic were that much more lethal than the third plague pandemic. Prior to the aDNA work, people speculated that medieval plague was a different pathogen altogether, but that hypothesis has been put to rest now. An alternative theory has been that plague could spread through human ectoparasites, and we found a novel way to test that theory. That resulted in this paper.
- idanman 9y agoCould it be that by the third plague more people developed immunity and therefore less were killed.
- geezerjay 9y ago> more people developed immunity Better yet, those who survived prior plagues were more likely to already be immune to the disease, and evolutionary pressure led to a more resilient population against this type of disease.
- BorisVSchmid 9y agoPotentially, but I am a bit sceptical. Plague reached a lot of new territory during the third pandemic (for example, australia and the americas), while still having a low mortality. One could check whether native populations to those continents were especially hard hit compared to people from European descent. I haven't heard anything like that.
- ziotom78 9y agoThere were several outbreaks in the centuries 14th-19th. Did the data used by the author cover all the major ones? My impression is that it is easier to recover data for the most recent outbreaks than for the older ones.
- BorisVSchmid 9y agoThere were indeed hundreds of outbreaks during those centuries. The outbreaks we selected were the ones for which we could find daily or weekly mortality records, as that gives you an epidemic curve that you can fit mathematical model to. We didn't use all of the cities for which we had outbreaks, but selected nine that covered a large part of the time period, and a large geographic region. Here is the list: Givry, France, 1348. Florence, Italy, 1400. Barcelona, Spain, 1490. London, England, 1563-1564. Eyam, England, 1666. Gdansk, Poland, 1709. Stockholm, Sweden, 1710-1711. Moscow, Russia, 1771. Malta, Malta, 1813.
- brndnmtthws 9y agoI never really understood why people hate rats, but love squirrels. I think rats are cool too.
- astura 9y agoMost people hate squirrels, at least around here.
- brndnmtthws 9y agoIn NYC it's pretty common to see people watching them and taking pictures of them.
- dentemple 9y agoThose are tourists.
- brndnmtthws 9y agoAnd what, they don't count as people?
- tnzn 9y agoAnd those who like rats are tourats ? (Sorry)
- scaryclam 9y agoI like rats in general (they make great pets) but I'd imagine people dislike them more than squirrels because they come into the home more readily. I don't know if you've ever had to live in a house with a rodent problem, but in case not, it's miserable.
- hajile 9y agoYet another paper discovers the obvious. The "cure" for the plague was 40 days off isolation of affected homes or cities. Rats and fleas don't respect human quarantines. Another factor is rats. They are killed by plague just like humans. At least one person should have noted large volumes of rats dropping dead everywhere, but that isn't mentioned in writings of the time.
- autokad 9y ago> " Rats and fleas don't respect human quarantines." rats dont travel as much as you think, even within cities. only when the rats piggy back on human travel, could they have spread the disease. https://www.nytimes.com/2015/04/26/magazine/the-rat-paths-of-new-york.html https://www.nytimes.com/2015/04/26/magazine/the-rat-paths-of... "But feral cats won’t stray three blocks beyond where they were born, and few mice will venture more than a hundred feet from their burrows in a lifetime."
- hajile 9y agoIf rats don't travel, then how do they spread the plague? If they do travel, then quarantine would not work. If they travel with humans, then we would expect to see massively higher infection and death rates among travellers due to prolonged times with infected rats as they dragged them everywhere (where is this evidence?) The plague spread across Europe at an enormously fast rate (some believe that hemorrhagic fever with a separate bubonic outbreak in Italy).
- Sundiata 9y ago> The "cure" for the plague was 40 days off isolation of affected homes or cities. In what way is that obvious?
- singhrac 9y agoResearch clearly funded by rats.
- aurelien 9y agoMaybe it spread from the sacramental bread eat in church ...
- scentoni 9y agoPSA: "Plague is widespread in much of California, including in the Sierra Nevada mountains and foothills. In a typical year, the Centers for Disease Control and Prevention (CDC) reports about ten cases of plague in humans per year in the western United States. However, during 2015, 16 human plague cases were reported." https://www.nps.gov/yose/planyourvisit/plague.htm https://www.nps.gov/yose/planyourvisit/plague.htm
- scentoni 9y agoRodent Plague Surveillance in California https://www.arcgis.com/apps/ImpactSummary/index.html?appid=6627dfd8b7f1485cbdfda824965e49b3 https://www.arcgis.com/apps/ImpactSummary/index.html?appid=6...
- david927 9y agoBoris, thanks for answering questions here. One more: has this raised any doubts that the Black Death was a Bubonic Plague?
- BorisVSchmid 9y agoDepends on how you mean the question. ancient DNA analysis has settled that the first two plague pandemics were Yersinia pestis, so if your question was on what kind of bacterium caused the Black Death - that is Yersinia pestis. If it is about the manifestation of the disease (the clinical symptoms), those we only know from historical descriptions and that is not something a model can change :-). So yeah, many infected people would still have had buboes. Buboes are also the expected result from plague acquired from fleas (whether they were human fleas or rat fleas). What might be less known is that there is a pretty high chance (10-20%) that a person suffering from bubonic plague progresses to pneumonic plague. That basically is a death warrant for that person, but it also means that he/she might spread the disease further through air-droplets. If the conditions are right, you might get a pneumonic plague epidemic intermingled with a bubonic plague epidemic. Model-wise, that is one scenario we haven't looked into, but we have seen something like that play out in Madagascar last year.