The mystery plague

Ever heard of cocoliztli?

In one way, it's shocking if you haven't, and in another, hardly surprising at all, because the vast majority of its victims were the indigenous people of Mexico and Central America, and history has a way of ignoring what happened to brown-skinned people.  Cocoliztli is the Nahuatl name for a contagious, usually fatal disease that struck Mesoamerica repeatedly, with the worst recorded outbreaks in the sixteenth century, killing an estimated ten million people.  This puts it in fifth place for the worst pandemics known, after the Black Death (estimated one hundred million casualties), Justinian's plague (fifty million), HIV/AIDS (forty million), and the Spanish flu (thirty million).  [Nota bene: if we're adding up total death toll, one of the worst is smallpox, but as that was endemic and widespread, I'm not counting that as a true pandemic.  In eighteenth-century Europe, for example, it's estimated that four hundred thousand people died of smallpox per year; and its introduction into the Americas decimated Native populations.  It's likely we'll never know for sure how big the death toll was, but it was huge.]

The symptoms of cocoliztli were awful.  Severe headache, high fever, vertigo, jaundice, and abdominal cramps.  The worst was the hemorrhaging -- victims bled from every orifice including the tear ducts.  Most of the victims died, usually between four and seven days after onset.

[Image is in the Public Domain]

There are two curious things about cocoliztli.  The first is that there hasn't been a confirmed case of it since 1813.

So where has it gone?  Ordinarily, infectious diseases occur at low rates until a confluence of events triggers a more widespread outbreak.  Consider, for example, the Black Death.  Bubonic plague (caused by the bacteria Yersinia pestis) has been present in humans for millennia, but a perfect storm occurred in the mid-fourteenth century that caused the most devastating pandemic in history.  First, it was the beginning of the Little Ice Age, and the lower temperatures drove rats (and the fleas they carried) indoors, and into contact with humans.  Second, trade throughout Europe, and with Asia (via the Silk Road), had really just started to gear up, and rats are notorious for stowing away on ships.  And third, the population had risen -- and larger, more crowded cities facilitate disease spread.

Cocoliztli, though, hit Mesoamerica hard, and seemingly out of nowhere.  Repeated outbreaks in 1545, 1576, 1736, and 1813 killed millions, but in between, we don't know where it went -- or why after 1813 it apparently vanished completely.

The second odd thing is that we still don't know what caused it.

The bones of presumed victims have offered up only debatable information.  Back in 2018, Johannes Krause, of the Max Planck Institute for the Science of Human History, found DNA in bones from victims of the 1545 outbreak that seems to come from a Salmonella enterica strain called Paratyphi C, but that doesn't mean that's what killed them -- and one epidemiologist has pointed out that typhoid fever, which is caused by S. enterica, doesn't have the same symptoms as cocoliztli.  Others suggest that its symptoms are more consistent with a viral hemorrhagic fever like Ebola, Lassa, and Marburg, but there are no viruses known that are endemic to the Americas and cause symptoms like that.

A rather sobering possibility is that the pathogen, whatever it is, resides in an animal vector -- that is, it's a zöonotic disease, one that exists in an animal population and is reintroduced to humans periodically upon contact.  If so, it's unknown what that vector might be -- but the jungles of Central America are a big place, and there are lots of animals there in which a pathogen might hide.

Whatever causes it, and wherever it went, it's to be hoped it's gone for good.  This would put it in the same class as the mysterious European sweating sickness, that caused repeated outbreaks in the late fifteenth and early sixteenth centuries, and then vanished, apparently permanently.  It, like cocoliztli, was highly infectious -- but the pathogen remains unidentified.

Cocoliztli left its mark on history.  The population of Mexico collapsed in the sixteenth century, largely due to the outbreaks, dropping from an estimated twenty-two million in 1500 to two million a hundred years later.  This undoubtedly contributed to the Spanish takeover -- something that reverberates to the present day.

It's also an enduring mystery.  How such a virulent disease could strike so hard, decimating an entire region, and then vanish utterly is bizarre.  But it does highlight how important epidemiological research is -- helping us to understand how pathogens cause disease, and how they jump from one host to the other.  Giving us, it is to be hoped, the tools for stopping the next pandemic before it happens.

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Space germs

I'm fully in support of pure research, which should be obvious to anyone who is a regular reader of Skeptophilia.  But sometimes I run into a paper that leaves me scratching my head.

This happened this past weekend when I stumbled upon a press release from the University of Exeter entitled, "Mammals Could Struggle to Fight Space Germs."  The gist was that a team led by microbiologist Neil Gow did a series of experiments exposing mammalian cells to lab-synthesized peptides containing two amino acids that have been detected in space but not found in terrestrial proteins (isovaline and α-aminoisobutyric acid), and they found that the cell cultures had a "weak immune response."  From this, they concluded that if we're exposed to extraterrestrial microbes, we might really suck at fighting them off.

[Image licensed under the Creative Commons Phoebus87 at English Wikipedia, Symian virus, CC BY-SA 3.0]

This seemed like a rather overblown conclusion, so I went to the original paper (always a good idea; even university press releases are often oversimplifications or miss important points).  In this case, though, the press release was pretty much spot-on.  Here it is, straight from the paper:

The discovery of liquid water at several locations in the solar system raises the possibility that microbial life may have evolved outside Earth and as such could be accidently introduced into the Earth’s ecosystem.  Unusual sugars or amino acids, like non-proteinogenic isovaline and α-aminoisobutyric acid that are vanishingly rare or absent from life forms on Earth, have been found in high abundance on non-terrestrial carbonaceous meteorites.  It is therefore conceivable that exo-microorganisms might contain proteins that include these rare amino acids.  We therefore asked whether the mammalian immune system would be able to recognize and induce appropriate immune responses to putative proteinaceous antigens that include these rare amino acids. To address this, we synthesised peptide antigens based on a backbone of ovalbumin and introduced isovaline and α-aminoisobutyric acid residues and demonstrated that these peptides can promote naïve OT-I cell activation and proliferation, but did so less efficiently than the canonical peptides.  This is relevant to the biosecurity of missions that may retrieve samples from exoplanets and moons that have conditions that may be permissive for life, suggesting that accidental contamination and exposure to exo-microorganisms with such distinct proteomes might pose an immunological challenge.

Okay, I'll admit that this is one possible conclusion you could draw; it certainly has been riffed on often enough in science fiction, starting all the way back in 1969 with The Andromeda Strain.  (You could argue that it goes back further than that, given that at the end of H. G. Wells's 1898 novel The War of the Worlds, the invading Martians are destroyed by terrestrial microbes to which they have no natural immunity.)

The other possibility, however, is that the microbes wouldn't affect us at all.  When pathogens attack our cells, they usually obtain ingress by bonding to receptors on the surface.  Those receptors can be amazingly specific; this is why there are so many strains of flu, some of which only attack birds or pigs... or humans.  The immune species, in this case, lack the surface proteins that can form bonds to the viral proteins, so they don't get in.  The result: no disease.

In fact, it's even more specific than that.  In 2006, an outbreak of H5N1 bird flu generated worries about a pandemic, until it was learned that although highly contagious in birds, it only affects humans if the virus binds deep in the lung tissue -- the receptors in the upper respiratory system aren't able to bind to the virus efficiently (fortunately for us).  The only ones who became ill were poultry workers who were exposed to dust and debris in poultry houses.  No cases of human-to-human transmission were recorded.

So my suspicion is that extraterrestrial microbes probably wouldn't be able to attack us at all.  And given that our tissues would lack the two oddball amino acids the researchers used in their experiments, it seems pretty likely that if the microbes did get in, they'd starve to death.  (Put more scientifically, our proteins would lack two amino acids they need, so we wouldn't be of much use to them as a food source.)

Of course, it's possible that Gow et al. are right, and extraterrestrial microorganisms would consider the Earth an all-you-can-eat buffet.  But given that (1) the number of extraterrestrial microorganisms we've actually studied is zero, and (2) there are equally persuasive arguments to the contrary, it might be a little bit of a premature conclusion.

Now, that doesn't mean we should be bringing outer space debris to Earth, sans quarantine.  Hell, I've read The Colour Out of Space, and last thing I want is to have a gaseous entity from a meteorite cause my limbs to crumble and fall off.  COVID-19 is bad enough, thanks.  We really don't need any more reasons to panic, however.  So for now, let's confine ourselves to dealing with threats that currently exist.

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Being in the middle of a pandemic, we're constantly being urged to wash our hands and/or use hand sanitizer.  It's not a bad idea, of course; multiple studies have shown that communicable diseases spread far less readily if people take the simple precaution of a thirty-second hand-washing with soap.

But as a culture, we're pretty obsessed with cleanliness.  Consider how many commercial products -- soaps, shampoos, body washes, and so on -- are dedicated solely to cleaning our skin.  Then there are all the products intended to return back to our skin and hair what the first set of products removed; the whole range of conditioners, softeners, lotions, and oils.

How much of this is necessary, or even beneficial?  That's the topic of the new book Clean: The New Science of Skin by doctor and journalist James Hamblin, who considers all of this and more -- the role of hyper-cleanliness in allergies, asthma, and eczema, and fascinating and recently-discovered information about our skin microbiome, the bacteria that colonize our skin and which are actually beneficial to our overall health.  Along the way, he questions things a lot of us take for granted... such as whether we should be showering daily.

It's a fascinating read, and looks at the question from a data-based, scientific standpoint.  Hamblin has put together the most recent evidence on how we should treat the surfaces of our own bodies -- and asks questions that are sure to generate a wealth of discussion.

[Note: if you purchase this book using the image/link below, part of the proceeds goes to support Skeptophilia!]

Trapped in the ice

Today in the "I've Seen This Movie, And It Didn't End Well" department, we have: scientists digging into glacial ice and finding heretofore-undiscovered species of viruses and bacteria.

Just this week, a paper called "Glacier Ice Archives Fifteen-Thousand-Year-Old Viruses" was released as a preprint on bioRxiv, detailing work by a team led by Zhi-Ping Zhong of Ohio State University.  Here's what the scientists themselves write about the research:

While glacier ice cores provide climate information over tens to hundreds of thousands of years, study of microbes is challenged by ultra-low-biomass conditions, and virtually nothing is known about co-occurring viruses.  Here we establish ultra-clean microbial and viral sampling procedures and apply them to two ice cores from the Guliya ice cap (northwestern Tibetan Plateau, China) to study these archived communities...  The microbes differed significantly across the two ice cores, presumably representing the very different climate conditions at the time of deposition that is similar to findings in other cores.  Separately, viral particle enrichment and ultra-low-input quantitative viral metagenomic sequencing from ∼520 and ∼15,000 years old ice revealed 33 viral populations (i.e., species-level designations) that represented four known genera and likely 28 novel viral genera (assessed by gene-sharing networks).  In silico host predictions linked 18 of the 33 viral populations to co-occurring abundant bacteria, including Methylobacterium, Sphingomonas, and Janthinobacterium, indicating that viruses infected several abundant microbial groups.  Depth-specific viral communities were observed, presumably reflecting differences in the environmental conditions among the ice samples at the time of deposition. 

On the face of it, it's unsurprising they're finding new viruses, because we find new viruses wherever we look in modern ecosystems.  Viruses are so small that unless you're specifically looking for them, you don't see them.

But four new genera of viruses is a little eyebrow-raising, because that means we're talking about viruses that aren't closely related to anything we've ever seen before.

This, of course, brings up the inevitable question, which was the first thing I thought of; what if one of these new viruses turns out to be pathogenic to humans?  The majority of viruses don't cause disease in humans, but it only takes one.  Science fiction is rife with people messing around with melting ice and releasing horrors -- this was the basic idea of The Thing, not to mention The X Files episode "Ice" and best of all (in my opinion) the horrifying, thrilling, and heartbreaking Doctor Who episode "The Waters of Mars," which is in my top five favorites in the entire history of the series.

So I'm hoping like hell the research team is being cautious.  Not that it ever made any difference in science fiction.  Somebody always fucks up, and large amounts of people end up getting sick, eaten, or converted to some horrifying new form that goes around killing everyone.

Lest you think I'm just being an alarmist because I've watched too many horror movies, allow me to point out that this sort of thing has already happened.  In 2016, permafrost melt in Siberia released frozen anthrax spores that sickened almost a hundred people, one fatally, and killed over two thousand reindeer -- after that region not seeing a single case of anthrax for at least seventy years.

On the other hand, it's understandable that the scientists are acting quickly, because the way things are going in the climate, glaciers will be a thing of the past in fairly short order.  Glaciers and polar ice sheets are time capsules, layer by layer preserving information about the climatic conditions when the ice was deposited, even trapping air bubbles that act as proxy records giving us information about the atmospheric composition at the time.  (This is one of the ways we've obtained carbon dioxide concentrations going back tens of thousands of years.)

However, it also preserves living things, including some that seem to retain their ability to be resuscitated nearly indefinitely.  I try not to panic over every little risk, but I have to admit this one has me spooked.  We don't have a stellar track record for caution, but our track record for saying, "Oh, yeah, this'll work!" and then unleashing a catastrophe is a good bit more consistent.

So let's be careful, okay, scientists?  I'm all for learning whatever we can learn, but I'd rather not be turned into a creepy evil being with a scaly face dripping toxic contagious water all over the place.  Call me picky, but there it is.

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This week's Skeptophilia book of the week is scarily appropriate reading material in today's political climate: Robert Bartholomew and Peter Hassall's wonderful A Colorful History of Popular Delusions.  In this brilliant and engaging book, the authors take a look at the phenomenon of crowd behavior, and how it has led to some of the most irrational behaviors humans are prone to -- fads, mobs, cults, crazes, manias, urban legends, and riots.

Sometimes amusing, sometimes shocking, this book looks at how our evolutionary background as a tribal animal has made us prone all too often to getting caught up in groupthink, where we leave behind logic and reason for the scary territory of making decisions based purely on emotion.  It's unsettling reading, but if you want to understand why humans all too often behave in ways that make the rational ones amongst us want to do repeated headdesks, this book should be on your list.

[Note: if you purchase this book using the image/link below, part of the proceeds goes to support Skeptophilia!] 

Tales of contagion

I have to admit to a morbid fascination with things that can kill you in nasty ways.

Tornadoes, hurricanes, earthquakes, mass extinctions from giant meteorite collisions -- and epidemics.  I remember first reading Daniel Defoe's A Journal of the Plague Year, about an outbreak of the Black Death in London in 1664 and 1665, when I was in college, and being simultaneously horrified and mesmerized at the scale of it.  An estimated 100,000 people died in two years -- a quarter of London's population.

But even that is dwarfed by two other epidemics.  First, there's the infamous outbreak of bubonic plague that started in 1347 and, by some estimates, killed one-third of the human population of the Earth -- something on the order of fifty million people.  The worst, though, was the "Spanish flu" epidemic of 1918 and 1919.  Odd that an event only a hundred years ago, and that killed an estimated 75 million people worldwide -- twice as many as World War I, which was happening at the same time -- is much less known.  Mention the Black Death, and almost everyone has an idea of what it is; mention the Spanish flu, and often all you get is a puzzled look.

Danse Macabre by Michael Wolgemut [image is in the Public Domain]

This all comes up because of a paper by Maria Spyrou et al. that appeared in Nature: Communications last week.  In it, the researchers describe looking for evidence of pathogens in the Bronze-Age burial sites -- and finding evidence that the bubonic plague has been with us for a long, long time.  The authors write:

The origin of Yersinia pestis and the early stages of its evolution are fundamental subjects of investigation given its high virulence and mortality that resulted from past pandemics.  Although the earliest evidence of Y. pestis infections in humans has been identified in Late Neolithic/Bronze Age Eurasia (LNBA 5000–3500y BP), these strains lack key genetic components required for flea adaptation, thus making their mode of transmission and disease presentation in humans unclear.  Here, we reconstruct ancient Y. pestis genomes from individuals associated with the Late Bronze Age period (~3800 BP) in the Samara region of modern-day Russia.  We show clear distinctions between our new strains and the LNBA lineage, and suggest that the full ability for flea-mediated transmission causing bubonic plague evolved more than 1000 years earlier than previously suggested.  Finally, we propose that several Y. pestis lineages were established during the Bronze Age, some of which persist to the present day.

Which is fascinating enough, but it bears mention that there are still a number of epidemics that scientists have no clear explanation for.  Here are three of the most puzzling:

1. "Sweating sickness."  In the late 15th and early 16th centuries, several waves of contagious illness swept through western Europe.  It killed fast -- starting with disorientation, fever, chills, aching joints, and finally progressing to delirium and copious sweating.  Most of the victims died within 36 hours of the onset.  It claimed a number of well-known victims, including Prince Arthur of England -- the son of King Henry VII, and brother of King Henry VIII.  Arthur's death at the age of fifteen put Henry in line for the throne, and set into motion events that would change the world -- such as the English Reformation and the founding of the Anglican Church.  Sweating sickness went as quickly as it started -- the last outbreak was in 1551, and it hasn't been seen since.  Scientists are still mystified as to the cause, but the speculation is it might have been a hantavirus, carried by mice.
2. The Dancing Plague of 1518.  In eastern France and western Germany, people were stricken by a disorder that caused shaking, mania, and... a desperation to dance.  People took to the streets, dancing desperately, many of them until they died of hunger, exposure, heat exhaustion, or stroke.  In Strasbourg alone, at the height of the plague, it was killing fifteen people a day.  It, like the sweating sickness, vanished as soon as it appeared, leaving everyone mystified as to its cause -- although some researchers suspect it might have been caused by ergot, a fungus that grows on wheat and rye and produces lysergic acid diethylamide -- LSD.
3. "Nodding syndrome."  This one is much more recent, having first emerged in the 1960s in Sudan.  It affects children, causing listlessness, stunting of growth (especially of the brain), and a peculiar symptom called a "nodding seizure," often triggered by eating or becoming cold.  The child's head bobs, and (s)he becomes unresponsive, the seizures lasting for up to ten or fifteen minutes.  It's progressive and fatal -- the usual duration being about three years.  To this day no one knows the cause, although some suspect it might be connected to parasitism by the roundworm Onchocercus volvulus, which is endemic in the area and also causes "river blindness."

So this combines my love of horrible things that can kill you with my love of unsolved mysteries.

Anyhow, I realize this is all kind of morbid, and I have no desire to ruin your mood.  After all, we live in an age where most of the worst diseases of antiquity have been vanished; even bubonic plague, if it's caught quickly, can be cured with antibiotics (and yes, there are still cases of it today).  Thankfully, we seem to have gotten rid of sweating sickness and the dancing plague, even if we've replaced them with Ebola fever and chikungunya and West Nile virus.  I'll still take what we've got today over life in the past, which was (accurately) described by Thomas Hobbes as "solitary, nasty, poor, brutish, and short."

Have a nice day.

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This week's recommended read is Wait, What? And Life's Other Essential Questions by James E. Ryan.  Ryan frames the whole of critical thinking in a fascinating way.  He says we can avoid most of the pitfalls in logic by asking five questions: "What?"  "I wonder..." "Couldn't we at least...?" "How can I help?" and "What truly matters?"  Along the way, he considers examples from history, politics, and science, and encourages you to think about the deep issues -- and not to take anything for granted.

Smoke screen

When evaluating a claim, it's often as important to recognize which questions to ask as it is to understand the science behind the claim itself.  What information did the author leave out -- intentionally or unintentionally?

The reason this comes up is an online article sent to me by a loyal reader of Skeptophilia entitled, "Studies Reveal 'Smudging' Eliminates Dangerous Bacteria in the Air."  The article describes the practice of "smudging," the burning of sweet-scented dried plants, and claims that the smoke is beneficial because it kills bacteria.  (S)he cites an earlier study, published in 2007 in the Journal of Ethnopharmacology, which has the following passage:

We have observed that 1 hour treatment of medicinal smoke emanated by burning wood and a mixture of odoriferous and medicinal herbs (havan sámagri=material used in oblation to fire all over India), on aerial bacterial population caused over 94% reduction of bacterial counts by 60 min and the ability of the smoke to purify or disinfect the air and to make the environment cleaner was maintained up to 24 hour in the closed room.  Absence of pathogenic bacteria Corynebacterium urealyticum, Curtobacterium flaccumfaciens, Enterobacter aerogenes (Klebsiella mobilis), Kocuria rosea, Pseudomonas syringae pv. persicae, Staphylococcus lentus, and Xanthomonas campestris pv. tardicrescens in the open room even after 30 days is indicative of the bactericidal potential of the medicinal smoke treatment.  We have demonstrated that using medicinal smoke it is possible to completely eliminate diverse plant and human pathogenic bacteria of the air within confined space.

So far, so good.  Assuming that the experiment was well-controlled and that there were no obvious design flaws invalidating the results, getting rid of pathogenic bacteria is certainly a good thing.  The author of the first article sums up thusly:

The basic concept is that by burning particular plants parts and resins, the energetic blueprint or spirit/intelligence of that plant is released, producing a medicinal smoke.  The smoke is then utilized to cleanse the energy of individuals, groups, spaces or object.  Herbs like Sage, Palo Santo, Copal, and Sweet-grass are common smudging herbs that are widely used for healing and to remove unwanted energetic and spiritual buildup and also to instill blessings...  Thanks to this amazing study we now know that smudging with sacred herbs is not only soothing to the mind and spirit, it is affecting the health and even safety of the actual environment in which it is done.

Setting aside the whole "energetic blueprint" and plant intelligence nonsense, there are a few questions that come to my mind that neither the author of the original study, nor the author of the post lauding its results, thinks to ask:

1. How many pathogenic bacteria were in the room to start with?  All we're given is the percent reduction (94%), which sounds like a lot -- but 94% of a tiny amount is an even tinier amount, and neither is significant.
2. If there are chemicals in smudging smoke that kill bacteria, could those chemicals be toxic to humans as well?  I'm reminded of all the articles that get passed around saying, "Substance X (usually some naturally-occurring compound) found to kill cancer cells!" -- and it turns out that yes, the substance kills cancer cells, but in vitro.  Whether it kills cancer cells in a human body, and does so without killing the human, remains to be seen.  After all, consider the fact that pissing in the petri dish will probably also kill cancer cells in vitro.
3. Are there other chemicals in the smoke besides the bacteria-killing ones that might be harmful?  In general, it seems like inhaling smoke of any kind is a bad idea.

So let's look at these questions one at a time.

For the first question, there were a lot of hyped-up articles like "There's a Time Bomb Ticking in your Household Dust" that presented a lot of scary stuff (like electron micrographs of dust mites, which look like a cross between a crab and that thing that burst out of the dude's chest in Alien) but little in the way of verifiable detail.  I did find an interesting article by Dr. Harriet Burge, director of aerobiology for EMLab P&K, a New Jersey-based indoor air quality assessment lab, and she had the following to say:

I generally do not recommend bacterial analysis of house dust except in a few unusual situations.  This is because we don't know how to interpret the results.  However, we do receive occasional requests for cultural bacterial analysis of house dust.  These analyses are done by dilution culture and data can be presented as total bacteria, general groupings of bacteria (i.e., Gram negative, Gram positive, Bacillus), sewage screens (total coliforms, Enterococcus, etc.) or species identification for the most abundant colonies.  Sewage screens usually involve presence or absence in house dust.  Otherwise, interpretation is based on the number of colonies present per gram of dust, and/or the relative composition of specific bacterial groups or specific organisms in the dust. 

Given that these requests are not rare, it seems appropriate to develop some interpretation guidelines, at least with respect to average or "usual" populations in house dust.  Unfortunately, few studies have been done documenting concentrations of total culturable bacteria or of any specific organism or group of organisms.  In my experience, these studies are rarely done because the dynamics of exposure to house dust are not clear, and because dust is not considered to contain human pathogens (or at least dust is not considered the primary source for human pathogenic bacteria).

So given that household dust isn't the most common source of transmission for human pathogens, it's unclear whether sterilizing the room would, under most conditions (i.e. we're not talking about an operating room here), lower the incidence of disease.

[image courtesy of photographer Christopher P. Michel and the Wikimedia Commons]

On to the second and third questions, which are related.  On a quick search, the first thing I turned up was a paper from Clinical and Molecular Allergy by Ta-Chang Lin, Guha Krishnaswami, and David S. Chi entitled, "Incense Smoke: Clinical, Structural, and Molecular Effects on Airway Disease" which had the following to say:

Incense smoke (fumes) contains particulate matter (PM), gas products and many organic compounds.  On average, incense burning produces particulates greater than 45 mg/g burned as compared to 10 mg/g burned for cigarettes.  The gas products from burning incense include CO, CO2, NO2, SO2, and others.  Incense burning also produces volatile organic compounds, such as benzene, toluene, and xylenes, as well as aldehydes and polycyclic aromatic hydrocarbons (PAHs).  The air pollution in and around various temples has been documented to have harmful effects on health.  When incense smoke pollutants are inhaled, they cause respiratory system dysfunction.  Incense smoke is a risk factor for elevated cord blood IgE levels and has been indicated to cause allergic contact dermatitis.  Incense smoke also has been associated with neoplasm and extracts of particulate matter from incense smoke are found to be mutagenic in the Ames Salmonella test with TA98 and activation.

So there's that.  I tried to find any studies of white sage (Salvia apiana) and sweetgrass (Hierochloe odorata) -- two of the most common plants in smudge sticks -- to see if either had been studied for toxic effects.  Nothing turned up.  There was lots of stuff about expelling negative vibrations, however.  So this one falls into the "we don't know" category.

On the other hand, it's pretty clear that smoke in general -- even wood smoke -- shouldn't be inhaled.  Incompletely-burned plant material contains polycyclic aromatic hydrocarbons, organic compounds that have been identified as not only carcinogenic and mutagenic, but also directly toxic.

So in the end, we're left with more questions.  On the one hand, incense and smudging smoke smells good and seems to kill nasty bacteria, which is good.  On the other, the bacteria that it kills almost certainly would never have made you sick in the first place, and the smoke is also potentially dangerous for you to inhale, which is bad.  In the final assessment, smudging your house if you have adequate ventilation is probably not going to hurt you, but isn't really going to do much to help you, either, unless you believe in "negative vibrations."

And in the even-more-final assessment, what we really should be doing, even more than burning dead plants in our houses, is asking questions.  Not simply buying whatever you read at face value -- in other words, recognizing that there are questions to be asked -- is the first step.

Sick unto death

New from the Dangerous Nonsense department: there's a new alternative-medicine model out of Germany that claims that viruses and bacteria aren't the cause of infectious diseases.

The website linked above, which was sent to me by a loyal reader of Skeptophilia, had me muttering imprecations under my breath pretty much right from the first line.  The author, Caroline Markolin, starts with a line from the famous 19th century biologist Rudolf Virchow: "If I could live my life over again, I would devote it to proving that germs seek their natural habitat -- diseased tissue -- rather than being the cause of diseased tissue."

Virchow was a brilliant pathologist and cellular biologist, but being good at some things doesn't mean you can't be dead wrong about others.  And the article conveniently fails to mention that Virchow not only disbelieved that pathogens caused diseases, he was also an ardent anti-evolutionist who considered Darwin an "ignoramus."

Be that as it may, we then are treated to quite a confection of nonsense.  Colds and flu, we're told, are actually the same thing, and are both caused by stress, not by viruses:

The common cold is linked to a "stink conflict", which can be experienced in real terms but also figuratively as "This situation stinks!" or "I've had it!". During the conflict-active phase the nasal membrane lining widens through ulceration, which is usually not noticed. In the healing phase, however, when the nasal tissue is being repaired, the nasal membrane swells up. A runny nose (healing always occurs in a fluid environment), headaches, tiredness, an elevated temperature or fever are all typical signs of a vagotonic healing process. If the cold symptoms are more severe, then this is commonly called the "flu". The claim, however, that "influenza" viruses are the culprits, has yet to be proven.

Nor has this claim, of course.  The "germ theory of disease" has over a hundred years of hard data supporting it.  This theory (if I can dignify it by that name) has a few vague generalities, a couple of ten-dollar words like "vagotonic," a photograph of a woman blowing her nose, so q.e.d., apparently.

We then find out that the "Spanish" flu of 1918-1919, that killed between 50 and 100 million people (hard numbers are difficult to come by, since the epidemic occurred during World War I, and many deaths in rural or isolated places went unrecorded), was not caused by a virus, it was caused by "stress."  People were under "territorial fear conflicts" and "death fright conflicts," and sickened from those; the acute, and frequently deadly, symptoms occurred when the body was trying to heal itself and the lung tumors caused by "stress" decomposed.

[image courtesy of the Wikimedia Commons]

Oh, and tuberculosis and AIDS aren't caused by pathogens, either.

And don't take antibiotics.  Ever.  Because they cause cancer.  Lung cancer, Markolin tells us, isn't caused by smoking; to hell with the research, which includes a study that demonstrated that 2/3 of the people who smoke will eventually die from conditions associated with tobacco use.  Cancer is caused by "shock," she says.  In a statement that should be an odds-on favorite for the Circular Logic Award of 2015, she states, "We have to bear in mind that every diagnosis shock can potentially cause... cancer," implying that the diagnosis of cancer is what caused the cancer to appear.

But how was the cancer there to diagnose if the diagnosis caused the cancer, you may ask?  To which I respond: stress vagotonic death fight conflicts.  And fear.  Stop asking questions, because you're going to stress me out and give me a cold.

Oh, and viruses, "if they existed," would "assist in the reconstruction of... tissues."  Because evolution, for some reason.  Microbes are our friends; all disease is caused by emotional conflict.

Makes you wonder, doesn't it, how plants get infectious diseases.  Maybe my tomato plants didn't get late blight last year, maybe they were just feeling lonely and unappreciated.

But I'm certain that Markolin would have some sort of bullshit response to this, too.  Probably that humans with all of their ugly unnatural habits are causing the plants to stress out, and so the tomatoes are picking up on our conflicted quantum vibrational states and becoming sick themselves.

Nothing whatsoever to do with pathogens.  Just like colds, flu, AIDS, tuberculosis, and the bubonic plague.

The difficulty here is that there is a germ of truth (rimshot) to what she's saying.  The mind does have a role in health; stress does cause physical manifestations, probably mediated by the hormone cortisol.  But this is a far cry from saying that all disease is caused by stress, and that pathogens have nothing to do with it.

The problem with all of this is not that a crackpot has a website.  Many crackpots do.  It seems to be a favorite hobby of theirs, in fact.  The problem is that naïve people will fall for this, and fail to seek out proper medical care for curable conditions.  So it's homeopathy all over again; a claim that is entirely unsupported by research and evidence, and only believable if you fall for some hand-waving foolishness that the students in my Introductory Biology classes could debunk without even breaking a sweat.  That hasn't stopped the story, however, from being picked up by Spirit Science, so it's popping up all over woo-woo alt-med websites just in the last few days.  (If you go to the Spirit Science article, don't read the comments.  Really.  I mean it.  It will result in your spending the rest of the day curled up in a corner, whimpering softly.  If you ignore this advice, allow me to say simply that, yes, there are people in the world who are this stupid.  And they vote.)

So the caveat emptor principle applies here, of course.  People should be smart enough not to believe appealing nonsense about preventing the flu by becoming less stressed.  But I still feel some sympathy with the folks who are ignorant, or desperate, enough to fall for something like this, and who will suffer the consequences of that ignorance.

And as far as Markolin and her idiotic theory, I'm about done with it.  The whole thing is stressing me out, and we can't have that.