Summary :

Acute time limiting life threatening refractory pulmonary edema even at times fatal is more painful than severe local intolerable pain what layman even including medical personals knew about scorpion envenoming. We are studying severe scorpion sting cases since 1976. Envenoming by Mesobuthus tamulus (an Indian red scorpion) result in autonomic storm, characterized by vomiting, profuse sweating, cold extremities and life threatening cardiovascular effects. We observed hypertension in 39%, pulmonary edema 29% and severe local pain at the site of sting without systemic effects in 24% cases. Fatality is 0.9% in adults and 7% in children. Prazosin a postsynaptic alpha-1 blocker antagonizes the venom action and act as physiological and pharmacological antidote. Since the advent of prazosin the fatality is reduced to <1% which was more than >40% during pre-prazosin era (1961-83). Cardiovascular morbidity and mortality depends upon the age of victim, season of sting, content of telson (a poisonous glands situated at the terminal segment of tail of scorpion attached with sharp curved stinger) at the time of sting and time lapse between sting and administration of prazosin.

Introduction :

Nearly 1000 species of scorpions belonging to six families have been mentioned, but only some species belonging to the family Buthidae, produces neurotoxin venom that is potent, lethal, toxic to human victims. Of 86 species found in India, Mesobuthus tamulus (an Indian red scorpion) and Palmaneus Garvimanus black scorpion (vernacular language called Ingali) often seen all over Kerala state are the common ones. Mesobuthus tamulus, is the most lethal species flourished all over western Maharashtra, Anantpur and Karnool districts of Andhra Pradesh, Chennai, Pondicherry and Madurai in Tamil Nadu, Bellary in Karnataka, part of Gujarat, Patna area from Bihar. Recently few deaths have been reported from rest of Maharashtra because of change in environmental temperature, routine use of pesticides, and chemical manures by farmers, result in change in venom as a part of acclimatization. Farmers, farm laborers are more prone to get stung by scorpion during handling debris, paddy husk in the months of October-September. Bare-feet walking young children in early darkness are at high risk of getting stung, simple wearing of slippers do not protect from sting. Scorpions often fall from loose tiles of huts in beds. Scorpion takes shelter in clothes (shirt shelves, trouser pockets), bedding and shoes.

Culprits :

Palmaneus Garvimanus (Big black scorpion)
It inflicts severe excruciating painful sting, mild swelling, sweating, and local fasciculation at the site of sting, transient bradycardia due to pain. No systemic involvement.

Mesobuthus tamulus (An Indian red scorpion)
It has red color claws, tails and legs with body cover with khaki color of size 2.5-4 inches long. Similar lethal scorpion a species capable of inflicting fatal sting are reported from north Africa, the Middle East, south Africa, Brazil, Trinidad, Mexico and Turkey. Despite of zoological differences among various species, the clinical presentation following envenomation is quite identical.

Venom :

Scorpion venom contains polypeptides, free amino acids, serotonin, hyaluronidase and various enzymes, which act on trypsinogen. It is the polypeptide, which is neurotoxic. P substance stimulates the cutaneous pain fibers. The mesobuthus tamulus venom is sodium channel activator and causes delay closing of sodium channels resulting in autonomic storm. The toxic content of venom causes inhibition of calcium dependent potassium channels.