November 16, 2021

Public mediums, not individuals, are superspreaders, concentrating pathogens from orders of magnitude of people

The big story about COVID-19 right now is the failure of the mass vaxx campaigns to stop the spread, just like this time last year saw the total failure of 100% mask compliance to stop the spread. (Although at least the masks did not give young people heart disease.) Soon I'll get to this topic -- why do vaccines fail when the disease is spread through a public medium (all coronaviruses, influenza, plague, cholera, etc.), as opposed to those spread through personal encounters (smallpox, HPV, measles, etc.).

But first, I'll have to develop one of the factors I think plays a big role in that. Even if it turns out not to matter for the topic of vaccine failure, it's still a crucial difference between the dynamics of public medium diseases and personal encounter diseases.

In contemporary sex ed classes, students hear the warning that, "You're not only having sex with that person, but everyone else they have had sex with (and everyone who those first-degree partners have had sex with, ad infinitum)".

There's something to this, but it is exaggerated and turns out to be the wrong category of diseases to issue such a warning about. How many other people has that person had sex with? Most people only have single-digit partners in an entire year, at most, while others are monogamous or even celibate for the year. Ditto for the number of partners for those first-degree contacts. There's almost no chance you're talking 100s, and possibly not even 10s, for the typical pair of sex partners.

Then there is the matter of how long the effects of those distant contacts last. If someone gave your partner an STD two years ago, but it has cleared in the meantime, they are no longer able to pass it along to you. For the purposes of measuring the indirect effect on you, it's as though your partner never had sex with that third person at all.

So, the warning should be modified to say, "You're having sex with everyone else who that person has *recently* had sex with" -- where "recently" is measured on the time-scale of the relevant diseases that could be passed along to you. If a disease clears up after 1 year, and your partner had sex with them 3 years ago, they are not included in the list of people the person has recently had sex with.

This is why the typical person is not a walking petri dish of STDs by the time they're 30 or 40. The pathogens clear up after some time, although not for all diseases, like those that can lie dormant. Therefore, during any single sexual encounter, a person is not exposing themselves to the pathogens of a large number of other people -- probably only single digits, and probably low single digits. That still allows for contagious diseases to rise in epidemic fashion, but it is not the gross interconnected web that the warning statement implied, and the epidemics won't be so bad.

The exceptions prove the rule here, as we see from people who do have high body counts, like gay men and prostitutes. It's worse in the case of gays, because a bunch of hyper-promiscuous people are having sex with each other, so the first-degree and second-degree and nth-degree contacts are also high body count people. During a single encounter among gays, the person could easily be exposed to 10s or 100s of others. This makes virulent wildfire-spreading diseases like HIV emerge among them, but not among heterosexuals.

Nor, for the most part, among prostitutes. While prostitutes have a high number of partners, their johns are mostly unfuckable losers. So when one john sees a prostitute, he is exposing himself to the diseases of her other recent johns, but those first-degree contacts have likely had 0 partners themselves during the past year -- that's why they're going to the prostitute, because they're desperate and unwanted. And prostitutes do not have sex with each other, so two high body count people are not going to have an encounter with each other, in the world of prostitution.

It's true that one john could have sex with two or more prostitutes, and indirectly link two high body count people. But the larger point remains -- any and all prostitutes within a given area are servicing the same local population of unfuckable losers, none of whom have extensive partner lists. So the web of connections does not spiral out exponentially like it does for gays, although certainly more so than among normal heterosexuals who don't visit prostitutes. So there's no HIV epidemic that will emerge within the (female) prostitute world.

As usual, I'm focusing on STDs to discuss person-to-person transmission because not even the strongest anticontagionist will argue that they don't require close personal encounters between an infected and a susceptible individual. It takes two to tango. They distill the essence of contagious disease dynamics.

* * *

Now let's shift to diseases whose pathogens are spread through a public medium, without encounters between the sick and the susceptible. Again the canonical example is cholera from the 19th C., spread by the medium of the public water system, where a sick individual's defecation (containing pathogens) entered the water supply through the sewers, and where a susceptible individual sampled that contaminated water every time they drew up water through a pump (for drinking, washing themselves, washing clothes, etc.).

The sick and the susceptible individuals never encountered each other during the course of the transmission. It was the public medium with which they both had contact -- perhaps separated by entire city blocks -- that spread the disease from one to the other.

In total contrast to the personal encounter diseases, look at how many other individuals you are exposed to by coming into contact with a public medium like a city's water system. It was everyone who was served by that system -- everyone whose defecation entered into the same body of sewer water. It's not as though each household had their own body of water that collected their waste, with no two households' wastewater bodies ever merging to form a single body of wastewater.

Rather, the public water supply reflected the whole collective that it served. And the size of that collective would have always been greater than mere single digits -- could be 10s, 100s, 1000s, or higher.

When I say someone is "exposing themselves to" all those other people, I don't mean they actually come into contact with the wastewater of every last one of them. I mean it in the sense of taking a risk, playing Russian roulette. More precisely, they are "sampling from" that population who contribute their wastewater to the whole system.

That is equally true for the class of encounter diseases like STDs, though: even if your current partner has traces of what was given to them by 5 recent partners, you won't necessarily pick up traces from all 5 of them. You will be sampling from those 5.

The main point is that a person samples from a much more gigantic size population when they come into contact with a public medium like a city water supply, compared to coming into contact with another individual human being. A city water supply could easily be a "walking" petri dish -- accumulating tons of particles across tons of pathogen species coming from tons of sick people -- whereas a particular individual person will not be.

How does that affect the potential for epidemics? Well, just imagine the early stages where the local frequency of the disease is small, say 1%. If it's an STD, 1% of your potential partners has it. If those partners have been monogamous recently, you're damn unlikely to get it. Even if they've had multiple recent partners, who have still left traces within your potential partner, that number probably reaches a max of 10. Sampling 10 individuals for a disease with 1% prevalence is still highly unlikely to give it to you.

But what if it's spread through a public medium? Then you have to avoid getting it after exposing yourself to 10s, 100s, or 1000s of people. By sampling 100 people for a disease with 1% prevalence, you're expected to get it. All it takes is that one critical exposure. Maybe your symptoms will be worse if you get even higher doses of it, but still, with the one crucial exposure, you've now got it, and you can pass it along in turn via the public medium.

If you're sampling 1000s for something with a 1% prevalence, you're expected to contract it 10s of times. And even if some of those infections are hunted down by your immune system, or they by chance don't reach their target organ after entering your body, the other infections will. You're going to come down with the disease, and contribute pathogens back into the public medium to complete the cycle.

The bottom line is that it's far easier to avoid contracting a pathogen when you're only rolling the dice a few times, vs. rolling them 10s or 100s or 1000s of times. Only public medium diseases allow for rolling the dice such a large number of times during any given contact with the transmission vector.

* * *

That brings us finally to the topic of "super-spreaders," a term with various definitions. Usually it means that a few sick individuals have a high number of contacts, any and all of whom they can spread the disease to, whereas most sick people have a small number of contacts, and are far less likely to contribute to the disease's continued spread.

I don't like using this term for individuals, though, because that highly-skewed distribution reveals exactly why such diseases do not become widespread and everlasting. Transmitting an encounter disease is a labor-intensive process -- if one sick person "wants to" spread it to 1, 10, 100, or 1000 others, they are going to have to put in higher and higher hours into the relevant activity.

That severely limits the share of sick people who will spread it at these high orders of magnitude -- unless the person does the activity for a living (and gets paid as a rising function of their number of contacts), or is just driven to it by a wandering, super-extraverted personality, what is the incentive to contact so many distinct other people during a single day, week, or month? None.

Of course, that makes it more spreadable than if every single sick person kept mostly to themselves. But it underscores the fragility of the transmission -- it crucially relies on a few people to do most of the heavy-lifting. Without them, it sputters out before catching on like wildfire.

And if it is a true encounter disease, quarantining a sick individual would work, by preventing contacts. And if there are only a small number of "super-spreaders" to quarantine, then the collective effect of a quarantine would also be massive and simple -- easier to lock up a small number, no matter how much they prefer being out and about, than to lock up a huge number. For example, implementing some real thot patrol by confining the local prostitutes and other high body count people, to curb an epidemic of an STD.

These all speak to the fragility and extinguishability of such a disease, whereas the term "super-spreaders" gives the impression of inevitability and broad reach of the disease.

* * *

The concept of "super-spreading" is better suited to public medium diseases, because there is a broad reach of, and nearly inevitable contact with the disease, when a medium is collecting pathogens from a huge number of people, and susceptible people cannot help but come into contact with the medium.

But it is the medium -- not a sick individual -- that has super-spreading powers. Its role in the transmission is not affected by the pathogens, so it is not limited in the number of contacts it can make with susceptibles. Public water doesn't move slower or otherwise fail to reach susceptible drinkers, just because it's polluted with cholera. And drinkers cannot detect the presence of cholera vs. unpolluted public water of their time and place, whether by sight, smell, etc., so they don't know when they should reject it for being polluted.

That is the opposite of an encounter disease, where having the disease limits their reach -- maybe an STD leaves someone bed-ridden, unable to get out and meet future partners, or maybe it leaves a visible sign that makes potential partners run the other way.

And more importantly, public mediums are not limited by the labor-intensive nature of spreading pathogens through encounters. A given volume of water can be excreted into by 1s, 10s, 100s, or 1000s of individuals -- it only depends on how many people happen to live in the region it serves. It does not need to increase in volume by the same orders of magnitude in order to serve those larger-sized populations. It does not need to do any of its activities by those higher orders of magnitude -- it just does its typical standard thing, and however many people come into contact with it, come into contact with it.

Ditto for the volume of air inside a building, to briefly return to coronaviruses. If it's a high-traffic building like a supermarket, that volume could collect the aerosolized breath of 1s, 10s, 100s, or 1000s of people during a day. An air volume of the same size, but in a low-traffic building like a storage facility (for things, not for livestock), may only be collecting the breath of the 1s of workers who work there.

The volume or size of the medium does not have to rise at all, let alone by orders of magnitude, in order to put exponentially larger numbers of people into an indirect chain of transmission. The indoor air is just doing its typical standard activity of being stagnant and filling up space, and however many people breathe into it (and breathe from it), do so.

Ditto for the insect population that spreads insect-borne diseases like malaria, plague, or Yellow Fever. The entire insect population acts like a public medium, similar to drops of water adding up to the entire water supply, or particles of air adding up to the entire indoor volume of air. People come into contact with this public medium by being bitten by the insect, which allows transmission of pathogens between two people who never have an encounter with each other.

And the same size mosquito population could be cohabiting with a human population that is 1s, 10s, 100s, 1000s, or millions. Mosquitoes don't have to boost their own population by 100 times, or do 100 times their swarming activity, in order to reach 100 times the human population -- however-many people are in their environment, are in their environment. And mosquitoes are not burdened down by being carriers of the pathogen (if anything, the pathogen will co-evolve to benefit the carrier).

That is the opposite of labor-intensive activities that spread encounter-based diseases, like a sick person who has to increase their dating-and-mating activities, to have sex with more and more partners in order to spread an STD to more and more susceptible people.

To conclude, public medium diseases unleash a more unrelenting and unavoidable assault on their targets, due to the medium collecting and concentrating the pathogens from such a large number of people. It is impossible for a person to sample the pathogen load of such a large population when it's an encounter disease, due to the labor-intensive nature of the activity that spreads it, and due to the hindering effect of the pathogen on its human carriers.

On the applied side, no public medium disease can be substantially curbed or eradicated through measures that target people, since they are not the source of the inevitable super-spreading phenomenon. Quarantines failed for cholera, plague, Yellow Fever, influenza, etc., just as they failed for COVID-19 -- along with masking, and now mass vaxx campaigns.

Rather, public health measures must target the medium through which transmission flows, which is the source of the high degree of connectivity among people. Such as separating outgoing wastewater from incoming potable water, chemically treating water to purify it, and so on. Or eradicating the local insect vector population, or at least putting up repellents or nets that keep them from biting sleeping people. Or for indoor-air diseases -- all respiratory epidemic diseases -- improving the ventilation to keep polluted breath from accumulating in the stagnant air, or releasing a purifier into the air to neutralize the pathogen (and which has no harmful side-effects).

Anticontagionism led the way forward, intellectually and practically, during the last peak of pandemics during the 19th C., and neo-anticontagionism must lead the way forward in the new pandemic era.

1 comment:

  1. If you remember the "law of large numbers," that's what's going on here. The observed frequency will reach the ideal probability when the number of trials gets arbitrarily large.

    If you have a fair coin, and flip it once or twice, it's possible to get 0 heads. But flip it 10,000 times, and heads will come up almost exactly 1/2 of the those times.

    There is greater variance in outcomes with small numbers of trials, but much less room for flukes when the trials get to be huge.

    Personal encounter diseases are more subject to the law of small numbers -- greater variance, where a fluke outcome could mean you escape getting the virus because you're sampling so few of the local population.

    Public medium diseases are driven by the law of large numbers -- the medium puts each individual into an indirect chain of transmission with huuuuge numbers of others. You're not sampling a small number of the relevant population, and flukes will not happen.

    Rather, the behavior will be more deterministic -- 1% or more of the population has cholera, and 100s or 1000s of people are connected to the same public water supply (untreated), ergo susceptible people are going to contract it, get sick, and shed even more cholera into the supply, driving up the epidemic.


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