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ZeroPointZero_ t1_j9adr7f wrote

From what I understand (my focus is Neuroscience, not Infectious Disease or Immunology), one of the main observed effects of COVID infection is inflammation of the vascular system [1]. Since the vascular system is responsible for maintaining pretty much all organs of the human body, infected individuals can exhibit a variety of symptoms based on the location of the inflammation. For example, neurological symptoms can indicate damage of the vessels around the brain [2].

This effect on the vascular system is not shared by the other pathogens/diseases you have listed, which (generally) target specific organs and/or tissues (respiratory, gastrointestinal, CNS) that are not as widespread and foundational as the vascular system. The variety of different possible targets (read: possible areas where the vascular system may suffer damage) is a very likely explanation for the variety of symptoms of COVID-19.

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ch1LL24 t1_j9alsk4 wrote

No, variable effects like that are not unique to Covid. The individual's specific biological situation, how they contracted the virus, and luck of the draw cause each infection to be somewhat idiosyncratic in most viruses. /u/redligand already has some good examples. I'll throw in Polio, which is known for its devastating paralytic effects but was also asymptomatic in 70% of children that contracted it. source

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KauaiCat t1_j9aqcud wrote

They have done studies which indicate different individuals are more/less susceptible to certain viruses based on genetics. For example, some studies have indicated that blood type makes people more or less susceptible. As an example, type O might be less susceptible to Covid, but more susceptible to norovirus.

I think it would be interesting if this turned out to be true for something like blood type where individuals may express one type, but may also carry genes for other types.

Having different genes in the gene pool would allow some members of the group to survive a certain pathogen because they were less susceptible because they expressed that gene(s) while carrying the gene(s) which would allow for less susceptibility to other viruses. This would allow the survivors to repopulate with the full gene package.

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Final_Maintenance319 t1_j9ax5vb wrote

Epstein-Barr virus has been associated with mononucleosis, Hodgkin and Non-Hodgkin lymphoma, Burkitt’s lymphoma, nasal carcinoma, Alice in Wonderland Syndrome, acute cerebella’s ataxia, dermatomyositis, lupus, rheumatoid arthritis, and Sjögren’s syndrome and multiple sclerosis. Would be nice to get a vaccine for it.

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Ituzzip t1_j9b7pjl wrote

On this list, rabies is the only disease that has the same end outcome for everyone who shows symptoms.

However it’s possible that some people could get exposed to rabies and don’t get an infection—that’s something that is difficult to measure, because you don’t know if viral particles entered the body and were cleared before establishing an infection, or if there just weren’t any particles that entered the body for some reason.

As for the others, the severity of the infection, and the ability for the immune system to clear it before it gets too advanced, will have a major role in affecting the outcome.

For most diseases, we’ve lived most of our lives assuming that somebody who never shows symptoms just didn’t get infected. With COVID we hear more about asymptomatic infections because of the emphasis on not exposing others, but most infections produce asymptomatic cases, and epidemiologists are aware of them. They just don’t get into the public consciousness because people aren’t too concerned when they have an infection that doesn’t affect their day to day life.

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Space_faces t1_j9bpgmi wrote

Replying to Ituzzip (#1,886,802)

There was a great episode of radiolab about rabies on which they referenced a study where rabies antibodies were found in folks in South America who were not dead or sick. Obviously antibodies aren't a guarantee of immunity, but like, how did they get them without a vaccine? Super interesting

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Nellie_88 t1_j9bq2v7 wrote

Those other illnesses have a range of effects for people too. The flu kills tons of people every year. Strep throat does not effect everyone the same. I got strep throat 2 years ago (34 y.o healthy) and got rheumatic fever and had heart damage and was hospitalized. Just because it’s not publicized doesn’t mean it doesn’t happen.

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BirdyDevil t1_j9byxq6 wrote

You can't even compare all these diseases - flu, rabies, and COVID are caused by viruses, salmonella and strep throat are bacterial infections. The similarities stop there - there are plenty of viruses that even infect bacteria. But as other people have said, no, a variety of outcomes is pretty normal with everything. It depends on your individual immune response.

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Balthasar-Hohenheim t1_j9c3dxv wrote

Replying to Space_faces (#1,888,538)

Rabies is effectively a two-step infection. It can infect and propagate in your "normal" cells like any other viral infection. In this stage the infection isn't necessary lethal and the virus can remain undetected in the body for long timespans (sometimes months). The immune system can also fight the illness off during this time period, which would lead to one having antibodies without being noticably sick.

The actual rabies infection that we usually think of happens when the virus enters nerve cells. From this point the virus just jumps from one neuron to the next straight to the brain without our immune system being able to interfere. One this happens one is as good as dead.

The tricky part is that the virus can enter nerve cells at any time during the initial infection (or straight from the initial wound) and at least in theory just one viral particle doing so is enough to kill. Our immune system is simply no built to deal with this situation as it functions on the principle of "use antibodies to catch most (but not all!) viral particles and let macrophages deal with all cells that still get infected". And that last part either doesn't happen at all or too late once the virus is in the nervous system. So we have to neutralize every virus particle before that can happen, hence why one should get treatment ASAP if there is any chance of one having been infected with rabies.

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CodeBrownPT t1_j9cin7l wrote

Replying to ZeroPointZero_ (#1,883,556)

This is wrong. Many existing viruses affect the vascular system. For example, the influenza vaccine is one of the strongest interventions we have to prevent cardiovascular mortality.

https://pubmed.ncbi.nlm.nih.gov/23474244/#:~:text=A%20spectrum%20of%20cardiovascular%20complications,exacerbation%20of%20existing%20cardiovascular%20disease.

Vascular effects are also not the explanation of varied symptoms. Here's a short excerpt regarding colds and their symptoms.

>The symptoms of the common cold appear to result from release of cytokines and other mediators from infected nasal epithelial cells and from an influx of polymorphonuclear cells (PMNs). Nasal washings of volunteers experimentally infected with rhinovirus showed a 100-fold increase in PMN concentration 1 to 2 days after inoculation.20 The influx of PMNs coincides with the onset of symptoms and correlates with a colored nasal discharge.21 A yellow or white nasal discharge may result from the higher number of PMNs, whereas the enzymatic activity of PMNs (due to myeloperoxidase and other enzymes) may cause a green nasal discharge.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7152197/

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Tight-laced t1_j9cjtnn wrote

Replying to princessParking (#1,890,090)

This study of US Army Personnel was the groundbreaking link. It took 10m samples over 20 years, so a huge sample size. 955 army Personnel developed MS over the course of the study, of those 955, 954 had had EBV infections prior to developing MS.

So if you develop MS, there's a 99.9% chance you've had EBV, versus a 95% chance in the general population. They tested for other viruses, none stood out like EBV.

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LearningIsTheBest t1_j9cnu05 wrote

Replying to ch1LL24 (#1,884,460)

> how they contracted the virus

I've read some articles which suggest a minimal or passing exposure tends to result in a less severe COVID infection and heavy exposure (e.g. a car ride) is correlated with more severe cases.

IIs there a definitive study on that? Just curious if you've read anything with good numbers.

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bakasana-mama t1_j9crkvz wrote

Husband and I were just talking about this - no one in our house has had it despite being in an area / our kids being in school with people who take zero precautions, contacts that have gotten it repeatedly, etc. I wonder if we had some immune protection having school age kids (ie our immune system being primed to fight it after years of being exposed to every respiratory virus going around the schools).

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tra_da_truf t1_j9cuh4v wrote

Covid gave me a fever and some snot.

I had strep about two months ago. Severely inflamed throat, loss of voice, severe headaches for days, glands and ears/throat swollen to the point that it cracked a tooth (which was a whole other nightmare) and I still have strep rash 2 months later. Antibiotics did nothing.

I really don’t know what the difference is in how things effect different people. Interesting for sure.

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hogey74 t1_j9cz7tn wrote

This trait isn't unique and your understanding of how that list of diseases "seem" isn't realistic. Rabies is the only one with a pretty universal outcome: it's basically 100 percent deadly once it's got a decent foothold in you. The others on your list have a wide spread of outcomes and experiences. The flu kills about 150 people per 100,000 infections. By comparison covid has been killing between 100 and 5,000 per 100,000 infections. Some people with the flu shrug it off, others are permanently injured by it's effects or are killed.

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Krail t1_j9d1kpm wrote

Replying to SvartSol (#1,889,554)

There are also multiple different "diseases" that are all caused by the same infectious agent (virus, bacteria, etc.). They just present completely different symptoms depending on various conditions such as the patient's age, how the infection occurred, etc.

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Civ6Ever t1_j9d2ivg wrote

Replying to Final_Maintenance319 (#1,885,722)

I always think about this. I was a pretty lazy teen, but after I got mono I reached a whole new level. Nearly failed my first semester of university, slept until 10-11 and had to start building class schedules around that (despite waking up at 630 to get ready every morning and arriving to high school an hour early), went from working out three days a week to feeling too tired to cook lunch (which didn't help the spiral). There are lots of possibilities - new environment, more difficult class level, less supervision, but I never felt so "out of it" in my life as that first two years.

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NW_thoughtful t1_j9d63en wrote

Replying to princessParking (#1,890,090)

The key is reactivation of the virus vs carrying the virus.

Think of the analogy of people who get cold sores. The virus lays dormant in the system and sometimes gets stirred up producing a cold sore. So the percentage of people who carry herpes virus in this example is much higher than the percentage of people who have it active at any given time.

With ebv, 95% of people have it and somewhere around 3 to 5% of people have it reactivate. When it reactivates, it can activate autoimmune processes such as MS as well as being directly inflammatory.

In the study on MS noted, most who had MS had EBV. The likelihood is that most of those actually had reactivated EBV.

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drowninginplants t1_j9d81sx wrote

Replying to Civ6Ever (#1,893,142)

I was never the same after having mono. I had a severe case along with strep and was hospitalized. I had a lot of hard life stuff going on, but after that, I just spiraled. It took years to get back on track, and the glands behind my ears have been sensitive ever since.

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MrCyra t1_j9d8top wrote

Replying to Ituzzip (#1,886,802)

Yeah, for instance salmonella has over 2500 strains and can cause anything from light stomach bug that goes away on its own to death. Less severe cases can be easily mistaken with food poisoning and such. So in theory it's way less scary than it seems on other hand it's so easy to prevent it that there is no point in playing lottery with this.

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Allfunandgaymes t1_j9dkfr2 wrote

No, not at all. It's very similar to influenza and other respiratory infections in that regard. It has greater risk for complications and mortality because it is a fairly novel zoonotic virus despite there being other coronaviruses that already infect humans.

Viruses which have "calling card" symptoms tend to be in the minority.

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Brittainicus t1_j9dt5q3 wrote

Replying to LearningIsTheBest (#1,891,687)

The general idea is if you get exposed to a lower viral load, you have less virus particles in your body which gives your immune system more time to find and destroy the virus before it multiplies to the point it can start doing noticeably damage.

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Twiz96 t1_j9dzegw wrote

Not true. Any disease will affect everyone differently. The four kills more people every year than Covid. In most cases granted not every case the people who die from things like Covid or the flue have pre existing medical problems

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David_Warden t1_j9fjb0z wrote

Replying to _dinoLaser_ (#1,891,638)

As numbers get close to 100% we have a tendency to think of them as much the same and sometimes miss something important.

Let's look at the numbers based on who hasn't tested positive for EBV.

5% in the general population 0.1% in the population with MS

This is a ratio of 50:1 which doesn't seem likely to be meaningless to me.

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Ituzzip t1_j9fydz4 wrote

Replying to Balthasar-Hohenheim (#1,889,820)

Do we actually know for sure the virus infects and propagates in non-nerve cells in these individuals? Viral particles can stimulate an immune response without ever infecting a cell (as in the way vaccines with dead virus work) so it doesn’t require propagation to stimulate antibodies in theory.

As to whether the immune system can stop rabies once it enters a nerve: animal bites take varying lengths of time to progress to symptomatic disease based on where they occur, with bites around the neck and face progressing to symptomatic rabies infections in days or weeks, but bites on the feet taking up to a year to reach the brain.

However, vaccination for rabies is effective at any time before symptoms appear. So it would seem that the body has ways of clearing the infection from nerve tissue. It is less effective at detecting the virus there and mounting a response, but when a response is stimulated by a vaccine, it seems to work.

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Ituzzip t1_j9fz004 wrote

Replying to MrCyra (#1,893,773)

Right, and not only are those strains all different but even identical strains could produce different sorts of disease in different people, based on things like prior immunity (or cross-immunity from a similar strain), the amount of infectious material that was ingested, how fast the digestive system is moving etc.

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jumpinin66 t1_j9pjf3c wrote

Strep throat is a great example. Group A streptococcus causes -

Strep throat

Scarlet Fever

Impetigo

Necrotizing Fasciitis

Cellulitis

Streptococcal Toxic Shock

Rheumatic Fever

Glomerulonephritis

There's even Pediatric Auto-immune Neuropsychiatric Disorders Associated with Streptococcus (PANDAS) which suggests anorexia may be caused by a strep A infection

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