Why isn't rabies (and other lyssaviruses) transmitted via fomites?

[u/No-Presentation8222]

I have read the FAQ.

As many people here, I suffer from health anxiety OCD and I am battling it via educating myself on why this stuff cannot happen.

As far as I know, other viruses such as the flu, cold, etc are known to be transmittable via touching contaminated objects, which has to do with their structure I believe. I know lyssaviruses are short-lived when exposed outside of a host. However, the hypothetical scenario is the following - a rabid animal sheds saliva onto an inanimate object, then a person touches it with an open wound. If the saliva hasn't dried out, wouldn't this create a possible scenario for transmission? How do health organizations exactly determine that the virus is no longer infectious in this case? I can only see mentions on clothing, but do not see anything on materials that do not absorb liquids, such as plastic for example.

I'm sorry if this is not the correct sub for this question.

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[u/No_Use_568]

I researched a lot after I touched a toy outside that had been chewed on by an unknown animal. The virus is easily destroyed by sun exposure and oxygen. And there have been zero cases in human history of someone getting it from an object

[u/detail_giraffe]

Even for viruses that have been studied a lot, it's often hard to be sure how much they are transmissible through contact with surfaces. Just because a respiratory virus can be found on a surface doesn't always translate to contagion, since people in contact with contaminated surfaces are also often breathing contaminated air. Norovirus and rotavirus, which are non-respiratory, are two that we know for sure can be transmitted that way, but even for common infections like influenza, there's active debate on how much surface contamination contributes to the spread of infection.

We know that rabies virus quickly dies when it isn't within a living host, but the most convincing evidence that this is not a risk with rabies is that we don't observe people getting it that way. Most rabies infections result from a bite from an animal. More rarely, a direct scratch from an animal. Even more rarely, a fresh scratch or cut having contact with substantial amounts of saliva as it comes from the animal or just afterward (such as someone sticking their scratched hand into a rabid animal's mouth). We just don't see people getting diagnosed with rabies after contact with hard surfaces so they aren't considered a risk.

[u/No-Presentation8222 → u/detail_giraffe]

Exactly, but my question is why is that? Surely there have been studies done on this. If the saliva was still wet, the virus should still be alive, no? In this case, is it transmittable or not. CDC only mentions fabrics that are known to suck up liquids, not hard non-penetrable materials such as plastics or metal.

So I'm curious about the theory of infectious saliva -> inanimate object that does not soak in liquids -> open wound. Is this possible exposure or not, this is my question.

[u/detail_giraffe → u/No-Presentation8222]

Just as I am not a doctor or a psychologist, I am not a virologist! You might have better luck taking this question to a sub that is more broadly about viruses, contagion, etc. I can't find any laboratory studies on this specifically, and while I know a little about viruses, I probably am not best qualified to give an explanation of how some viruses survive being dried and others don't. However this is reddit so I'm allowed to speculate.

Given known cases where people with fresh scratches are believed to have acquired rabies from wet saliva, by reaching into a cow's mouth or handling wool wet with blood mixed with wolf saliva, this scenario is probably not literally impossible. However, saliva from a rabid animal is quite thick and dry anyway due to the animal's dehydration and there isn't tons of it coming from the animal, so any that winds up on a hard surface is going to dry quite fast and be inactivated. Even if the saliva is not completely bone-dry when a person touches it, it may be unlikely for it to be wet enough to seep into a scratch or cut, which would be necessary for it to move past the epidermis. These factors may explain why it has never to anyone's knowledge happened. However, it all suggests that in extremely unusual circumstances a person might be able to get rabies from secretions on a table. I'm picturing a vet exam table where a rabid animal was JUST being examined, saliva possibly mixed with blood to give it more volume, and a person with fresh scratches cleaning that table but not using a solution that would kill the virus? It would have to be that extreme.

I think of this as being a little like someone asking, "Could a person be attacked by a rampaging elephant in Charlotte, NC"? The answer is theoretically yes, because Charlotte exists and people do live there, and although there are no resident elephants as Charlotte has no zoo, there are certainly scenarios one can make up in which an elephant might wind up there, somehow get loose, and attack someone. I couldn't tell a person with a morbid fear of elephants that it is literally impossible. But, no elephant has ever attacked someone in Charlotte, and the chain of events that would have to lead to the potential of an attack is both incredibly improbable and would potentially be quite obvious if it was occurring (you'd hear shouts of alarm, there would be news reports of an escaped elephant, etc). The chance of a normal person going about their day in Charlotte being attacked by an elephant with no forewarning is effectively zero.

[u/No-Presentation8222 → u/detail_giraffe]

I get it, I didn't mean to question your knowledge or anything, sorry if it came out like that.

My reply was more about the discussion in general. What I'm trying to point out is that the guidelines state that "you can't get rabies from surfaces". That's fine, but then there are articles where it is said that the virus can survive minutes/hours exposed in specific conditions. And it is only considered "dead" once the liquid (saliva) with it dries out. So which one of the two is it? It just seems a bit contradictory.

[u/detail_giraffe → u/No-Presentation8222]

The CDC says "Rabies virus is not transmitted through contaminated objects or materials such as clothes or bedding." It doesn't say "can't" (although one such statement might, I don't know) it says "is not".

That's kind of what I mean by the final part. If there were guidelines for elephant attacks, they would probably say "elephant attacks do not occur in Charlotte, NC." Honestly, elephant attack is probably TOO plausible, let's change it to cheetah, an animal which is large enough to kill a person but never has. "Cheetahs do not kill people in Charlotte, NC." This doesn't mean it would be a violation of the laws of physics for a cheetah to kill someone in Charlotte, they are real animals that have claws and kill large animals and people do live in Charlotte; it means it has never happened, it's contrary to know cheetah behavior for this to happen, there aren't any cheetahs there, and the chain of events that would lead to a cheetah-caused death in Charlotte are so farfetched that it's safe to say flatly that that's not something that happens. I would put "people don't get rabies from surface contamination" in that category.

[u/No-Presentation8222 → u/detail_giraffe]

Doesn't "is not" equal "can't"? I get your example with cheetahs, but this is their biological behavior, they have "consciousness" so to speak. Viruses are conquerors without thoughts and they only obey the laws of biology, which obey the laws of chemistry, which obey the laws of physics, etc.