In the somewhat disturbing video below, a single drop of venom from a Russell's viper is enough to cause a cup of blood to coagulate into a gelatin-like slab of clotted matter:
If that wasn't enough to make you swear off YouTube forever, imagine that same process happening inside your own blood vessels
Russell's viper, or Daboia russelli, has a broad range throughout Southeast Asia and is one of the primary causes of snakebite in the region, according to Max Alan Nickerson, a herpetologist at the Florida Museum of Natural History.
The venom of the Russell's viper, like that of many snakes, is a complex combination of a variety of components that can either encourage or block blood coagulation. Procoagulating factors interact with naturally occurring clotting proteins in the blood and can cause a cascading reaction, resulting in blood clots in vessels that can affect various organs throughout the body, according to Nickerson.
The clotting properties of Russell's viper venom actually make it useful in medical laboratory tests used to look for the presence of special anti-coagulating factors in a patient's blood.
Somewhere between 40 and 70 milligrams of Russell's viper venom is usually enough to kill a person. A single snake can carry up to more than 250 milligrams of venom, but not all snake bites deliver the same amount of poison.
The amount of venom in a bite varies from none to nearly emptying the venom gland, Nickerson said in an email.
Russell's viper venom can also affect the pituitary gland, the small pea-sized organ involved in hormone production. A 1987 study of 24 people that had previously been bitten by the viper found that 7 had clinical features of hypopituitarism, which often results in the loss of secondary sex characteristics like curviness in women and facial hair on men.
Russell's viper envenoming may thus produce a disorder resembling Sheehan's syndrome, a pituitary condition seen in pregnant women, the study's authors wrote in the Lancet.
If you are unlucky enough to be bitten by a Russell's viper, seek medical attention and don't try to suck the venom out of the wound. Antivenom, which is made by giving a diluted solution of snake venom to an animal and then collecting the antibodies produced in response, is your best chance to avoid lasting damage or death.