Sicarius thomisoides (Six Eyed Sand Spider) Venom?

[Brewser]

Many different types of Venom.
criticism 'May' be construed as spiteful and venomous as well

 

[MorbidArachnid]

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7694614/

Link to them actually testing Sicarius thomisoides venom and demonstrating it's ability to produce a necrotic lesion in rabbits. Venom potency is a lot of things, there's the volume of venom injected (which Sicarius can produce and inject more metric volume of venom because of their larger size), there's the concentration of the protein that causes detrimental effects (which in Sicariidae is the Phospholipase D protein, and this is where most of the statements about Sicarius and Hexophthalma potency come from because they do seem to have higher concentrations of this protein than Loxosceles do as a whole), and then there's the activity level of that protein. You can have a lot of venom injected at a very high concentration of protein and still have only mild effects because the protein didn't interact with any of your cells. Maybe the protein is a different isoform that can't bind to the receptors as well, or there aren't receptors at all, or maybe your body is just really good at isolating and neutralizing the venom before it has any serious effect. I don't know if any of these apply to Sicarius venom, but the paper does suggest Sicarius thomisoides has a lower activity level of protein than Loxosceles laeta. That being said, the venom still caused hemolytic and cytotoxic effect on human cells in a petri dish and caused a small lesion on rabbits, so it clearly can cause necrotic lesions and should still be treated as medically significant. I also think that the general reports of it rotting your arm off are largely exaggerated. I still haven't been able to find any primary or solid sources on what the human bite reports actually are for Hexophthalma, some papers say there was only one confirmed bite and the person lost an arm, some say he died, some say it wasn't confirmed but suspected based on the description of the spider, some say there was one bite where someone lost an arm and another bite that was a death, some say three confirmed bites. Does anyone have the actual case report for any of these? Even trying to track back through the sources I'm not getting anything. Like I see where they're cited at the bottom of papers but I can't find the original sources, at least one of them on a bite of a Sicarius tropicus is in Portuguese.

 

[Chrystie]

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7694614/

Link to them actually testing Sicarius thomisoides venom and demonstrating it's ability to produce a necrotic lesion in rabbits. Venom potency is a lot of things, there's the volume of venom injected (which Sicarius can produce and inject more metric volume of venom because of their larger size), there's the concentration of the protein that causes detrimental effects (which in Sicariidae is the Phospholipase D protein, and this is where most of the statements about Sicarius and Hexophthalma potency come from because they do seem to have higher concentrations of this protein than Loxosceles do as a whole), and then there's the activity level of that protein. You can have a lot of venom injected at a very high concentration of protein and still have only mild effects because the protein didn't interact with any of your cells. Maybe the protein is a different isoform that can't bind to the receptors as well, or there aren't receptors at all, or maybe your body is just really good at isolating and neutralizing the venom before it has any serious effect. I don't know if any of these apply to Sicarius venom, but the paper does suggest Sicarius thomisoides has a lower activity level of protein than Loxosceles laeta. That being said, the venom still caused hemolytic and cytotoxic effect on human cells in a petri dish and caused a small lesion on rabbits, so it clearly can cause necrotic lesions and should still be treated as medically significant. I also think that the general reports of it rotting your arm off are largely exaggerated. I still haven't been able to find any primary or solid sources on what the human bite reports actually are for Hexophthalma, some papers say there was only one confirmed bite and the person lost an arm, some say he died, some say it wasn't confirmed but suspected based on the description of the spider, some say there was one bite where someone lost an arm and another bite that was a death, some say three confirmed bites. Does anyone have the actual case report for any of these? Even trying to track back through the sources I'm not getting anything. Like I see where they're cited at the bottom of papers but I can't find the original sources, at least one of them on a bite of a Sicarius tropicus is in Portuguese.

So. I am not a spider scientist. BUT I lived in a rural Tanzanian village for almost two years and treated (or attempted to treat) multiple bites of what I can only assume to be this class of spider bite. We couldn't come up with any other culprit. It starts as a bothersome wound, an assumed insect bit, almost like a large cystic pimple that is weeping. When squeezed and/or drained, it is like a plug of ...have you ever seen videos or pics of "pink slime"? It's almost like that. A pink mess of dissolved flesh, out of a gaping hole. When cleaned out, the wound just continues to weep, like it is bleeding, but the excretion is clear and a bit pink. It just flows and flows. And the size of the hole grows and grows.

This is western tanzania on the southern end of Lake Tanganyika. THe only know locations for these spiders is Namibia and South Africa, so I suspect a previously undocumented species. These bites are not common, but they are nasty.

Any idea on anything that might be used to treat and /or neutralize this venom?


BTW the photo is a current wound of a child my friend over there is attempting to treat.

 

[MorbidArachnid]

Any idea on anything that might be used to treat and /or neutralize this venom?

That sounds awful, and no I'm not a doctor nor do I have any medical training at all, nor am I a spider scientist. Sorry. I think there's not a lot of research into these bites because the number of bites are presumed to be very rare, they don't typically live around people and prefer open undisturbed desert, they're very shy, and they seem reluctant to bite unless one is pressed against the skin. If you are getting a number of instances of bites I would definitely try to get eyes on it, a lot of universities will have a bug ID clinic or will accept samples sent to them. I'd try to contact an arachnologist that works at a nearby university or is somewhat local, catch the spider and sending it to them is the best way to get an ID and if it's a Hexophthalma that would prove these spiders do bite people and work needs to be done on making an antivenom or establishing a system of care for these bites. I will also say that it's impossible to ID a spider just off a bite, a lot of things can look like a spider bite and with Sicariidae especially these bites are vastly misdiagnosed. Necrotic effects on a wound are not good indicators of a Sicariidae bite, as secondary bacterial infections and bacterial infections in general also can cause necrosis. The location is also unusual for a Hexophthalma, these spiders don't typically climb and aren't very prone to wandering. You would have to have been sleeping out in the desert and rolled over one basically. I would definitely try to catch or at least take a photo of the culprit next time a bite happens and try to contact an arachnologist to get a proper ID, I'm sorry I can't really give you any help on medical treatment.

 

[Chrystie]

Thanks for your reply.
Well the reason that the sand spider thing seemed plausible is because the region is very sandy and fairly arid for at least half the year, and because these people sleep in mud brick huts on dirt floors and sometimes children will nap on the sand outside. I believe the area is referred to as highland bush. I am not even sure where the closest university is. The closest indoor supermarket is a three hour drive through the mountains. There did not appear to be normal signs of bacterial necrosis (skin discoloration, puss, purification, etc). If they are able to catch one, I will definitely have them save it, or I will if I head back here in the next few months. Thanks. Further replies are welcome.