Scrutable

A huge swathe of severe zoonotic diseases seem to originate in bats, as opposed to okapis, orang-utans or oxen. Any particular reason why?

Why are humans so plague ridden? Asks a bat on the Scrutabat forum.

bjn wrote: ↑

Tue Mar 17, 2020 9:42 pm

A huge swathe of severe zoonotic diseases seem to originate in bats, as opposed to okapis, orang-utans or oxen. Any particular reason why?

Because they’re insect eaters perhaps? Insects themselves are pretty bad for disease transmittal.

Okapis and orang utans are are pretty solitary whereas bats can have massive roosts, so maybe population density makes it easier for infections to spread.

Fishnut wrote: ↑

Tue Mar 17, 2020 11:11 pm

Okapis and orang utans are are pretty solitary whereas bats can have massive roosts, so maybe population density makes it easier for infections to spread.

And they fly around, so can cover decent distances in a night. Do bats from different roosts interact, or are they strictly territorial?

Because large roosts with some cross-pollination could be very effective at generating and moving new diseases.

Grumble wrote: ↑

Tue Mar 17, 2020 10:29 pm

bjn wrote: ↑

Tue Mar 17, 2020 9:42 pm

A huge swathe of severe zoonotic diseases seem to originate in bats, as opposed to okapis, orang-utans or oxen. Any particular reason why?

Because they’re insect eaters perhaps? Insects themselves are pretty bad for disease transmittal.

Fruit bats carry a large number of zoonotics too: Rabies, Sars, Ebola and Nipah.

lpm wrote: ↑

Tue Mar 17, 2020 9:53 pm

Why are humans so plague ridden? Asks a bat on the Scrutabat forum.

Hahaha

I'm guessing, but it's probably something to do with the combination of their mobility and high population density when roosting. In a weird way, they are almost a parallel of the current human population (teeming cities with efficient long-distance travel systems). I imagine viruses travel really fast through bat populations, which probably means that bats have top-notch immune systems and viruses get a lot of selection pressure for transmissability.

Bats are also mammals, so there's maybe less of a jump to be made to humans. Many flu strains are basically gut viruses of waterfowl, so it's probably a bigger leap for a flu strain to get into people than a bat virus. H5N1 and H7N9 bird flu strains have had repeated infection events in humans with short transmission chains but have never really taken off (thankfully).

Also people eat bats, which provides contact between the species.

Possibly the fact they sh.t everywhere in a factor. I visited a church somewhere that had a sheet stretched out under the corner of the roof some bats were roosting in to protect stuff. And batshit is probably full of viruses, and quite dry and dusty I imagine, so easy to inhale.

raven wrote: ↑

Wed Mar 18, 2020 12:28 pm

Also people eat bats, which provides contact between the species.

Possibly the fact they sh.t everywhere in a factor. I visited a church somewhere that had a sheet stretched out under the corner of the roof some bats were roosting in to protect stuff. And batshit is probably full of viruses, and quite dry and dusty I imagine, so easy to inhale.

I don't know about viruses, but bat droppings can be a potent source of histoplasmosis fungal spores.

I've struggled to untangle the chain of causality because I'm a layperson, but bats have remarkable immune systems, and a remarkable response to inflammation because of the high metabolic rate required for flight (bats are the only mammals that are capable of powered flight) - link

They are plague ridden because they can tolerate it

insignificant wrote: ↑

Wed Mar 18, 2020 1:56 pm

I've struggled to untangle the chain of causality because I'm a layperson, but bats have remarkable immune systems, and a remarkable response to inflammation because of the high metabolic rate required for flight (bats are the only mammals that are capable of powered flight) - link

They are plague ridden because they can tolerate it

This ^

So basically a red queen arms race between a highly effective immune system (compare to the rest of us mammals) and viruses evolving to survive in it? Nae problemo for the little flappy f.ckers, but species hop for a virus infectionageddon? Kinda like superman's species evolving with kryptonite then being super powered when away from it.

ETA, thanks for the linky insignificant.

There are several factors, all of them already mentioned I think.

Bats come into contact with lots of diseases because they roost and breed (and in some cases hibernate) colonially, and are therefore in contact with a lot of other individuals and their bodily secretions. Bats are far less well studied than birds (because it's very difficult!) but they do seem to be highly mobile. Many species are seasonally migratory, just like birds, but due to the lack of research we don't really know much about where any of them go. Swapping between roosts is likely to be extremely common, if birds are anything to go by. They also live a lot longer than rodents (decades rather than years) which gives more time to build up chronic infections.

They also have strong immune systems that impose a selection pressure on pathogens to become highly virulent, ie to spread between individuals before the immune response kicks in.

People and bats are also in close contact. In urban areas they will roost in buildings, pissing and sh.tting everywhere. People have exposed water tanks, wet-room bathrooms adjacent to kitchens, don't use soap, etc. And in rural areas people actively seek out bat colonies in order to hunt them. It would be easy to, say, pick up a dead bat (thus touching its poo or wee or blood) and then smoke a cigarette, even if the disease isn't passed directly via consumption.

I don't think insectivory is a direct risk-factor here, as viruses tend not to pass from insect to mammal via consumption (some parasites do this, though).

That said, it's looking likely that the original host of 2019-nCoV was a pangolin, based on many recent papers on bioRxiv. Pangolins are very different to bats - secretive nocturnal armadillo-like creatures that mostly creep about on the floor. These are hunted (illegally in most cases) for food and Chinese traditional medicine, trafficked from all across Asia and Africa. As populations become depleted (many species at risk of extinction), people are coming into contact with increasingly remote populations, and so the risk of encountering and spreading a novel pathogen increases very quickly. And as the commercial value of pangolin increases (due to scarcity) it becomes increasingly commercially viable to go ever further afield.

Despite being signatory to international conventions prohibiting the trade in endagered wildlife (CITES being the major example), Asian countries haven't bothered to do much about the wildlife trade - until now, when suddenly they can just shut them down immediately and throw everyone in prison. If the ban continues it will be good news for restricting the emergence and spread of novel zoonoses, good news for conservation, and potentially good news for public health if people seek out effective medicine instead.

If it's proven for definate that Pangolins were the source of COVID-19, I hope the major conservation charities make a big effort to publicise it. Then hopefully people would stop using Pangolin parts in Chinese "medicine" and as a dick-waving status symbol and it might have a chance to recover population wise

CF

Cardinal Fang wrote: ↑

Wed Mar 18, 2020 4:19 pm

If it's proven for definate that Pangolins were the source of COVID-19, I hope the major conservation charities make a big effort to publicise it. Then hopefully people would stop using Pangolin parts in Chinese "medicine" and as a dick-waving status symbol and it might have a chance to recover population wise

CF

Judging by the response so far (China and Vietnam, possibly others already shutting wildlife markets by force) then the wildlife charities won't even need to. They've been proven correct and what they've been saying all this time is being listened to. The ability to stop the illegal trade was there all along, of course.

Bird on a Fire wrote: ↑

Wed Mar 18, 2020 4:34 pm

Cardinal Fang wrote: ↑

Wed Mar 18, 2020 4:19 pm

If it's proven for definate that Pangolins were the source of COVID-19, I hope the major conservation charities make a big effort to publicise it. Then hopefully people would stop using Pangolin parts in Chinese "medicine" and as a dick-waving status symbol and it might have a chance to recover population wise

CF

Judging by the response so far (China and Vietnam, possibly others already shutting wildlife markets by force) then the wildlife charities won't even need to. They've been proven correct and what they've been saying all this time is being listened to. The ability to stop the illegal trade was there all along, of course.

As I understand it, they shut them down for SARS, too. Then re-opened them.

Corrupt and nationalist regimes will not act in the world's interest without being pressured or forced to do so, something we are seeing the world over right now.

A review of Bat Coronaviruses in China