Yellow Scorpion

Tityus bahiensis

Yellow Scorpion (Tityus sp)

Scorpion stings are an important cause for concern in Brazil because they occur frequently and also have the ability to induce severe and often fatal reactions to their venom. Research conducted in a Brazilian clinical study included data from 4 patients who were suffering from scorpion stings and who had all developed heart failure and pulmonary edema.

Three of the 4 patients died within 24 hours of being stung. The autopsy results of some of the patients indicated that they also suffered from vascular congestion probably due to circulatory failure as a result of Yellow Scorpion venom being present in the blood which physician’s believe could have triggered death (CUPO et al., 1994).

One of the case studies examined a young boy who was stung by the Yellow Scorpion because he experienced intense pain with immediate and frequent vomiting occurring right after the sting. The initial evaluation of this patient revealed that he was severely dehydrated and was experiencing cardiac arrhythmias. Interestingly enough all of the patients in this clinical case report study suffered from cerebral edema and dilation of their cardiac chambers, all of which had visible blood clots in their heart (CUPO et al., 1994).

Tityus serrulatus

Additional studies were conducted in a laboratory setting using mice to test the toxic effects of scorpion venom. In this experiment the mice who were exposed to the venom indicated that Yellow Scorpion stings have the ability to induce seizures. Mice that were injected with Yellow Scorpion toxin were also subject to massive pyramidal neuronal loss in the dorsal hippocampal region of the brain (SANDOVAL and LEBRUN, 2003).

The researchers that examined these effects were interested in the possible connection to a condition in Humans known as Hippocampal sclerosis. Hippocampal sclerosis is described as a common type of neuropathological damage resulting from neuron cell loss primarily occurring in the hippocampus. A very long-standing question is whether hippocampal sclerosis is the consequence of repeated seizures, or whether it plays a role in the development of the epilepsy (JEFFERYS, 1999). The researchers who conducted the mice experiment have suggested the possible benefits of incorporating the Yellow Scorpion toxin in attempt to design a new effective antiepileptic drug (SANDOVAL and LEBRUN, 2003).

Between the most important and dangerous species occurring in Brazil are Tityus serrulatus, Tityus bahiensis, Tityus stigmurus and Tityus cambridgei.

The venom of these animals doesn't produce necrosis or hemorrhagic effect but it affects the permeability of neurons and muscles. Some of the most important toxins are:

Alpha toxin: decrease or block the inactivation of Na+ channels voltage-dependent resulting in constant depolarization of the cells.

Beta toxin: enable or facilitates the activation of Na+ channels voltage-dependent, causing the cell depolarization.

Blockers of K channels: block the K channels. It causes a retardation on cell polarization return for difficult the ion flux trough this channels.

Blockers of Cl channels: block the Cl channels. It prevents the cell polarization.

Tityus serrulatus attacking a cockroach during a lab experiment

References:

Becerril, B. et al, "Toxins and genes isolated from scorpions of the genus Tityus", Toxicon (1997) 35:821-835.

Cupo, P., Jurca, M., Azevedo-Marques, M., et al. 1994. Severe Scorpion Envenomation in Brazil: Clinical, Laboratory and Anatomopathological aspects. Rev. Inst. Med. Trop. Säo Paul. Vol:36 (1) 67-76.

Jefferys, John G. R. 1999. Editorial: Hippocampal sclerosis and temporal lobe epilepsy: cause or consequence? Brain: Oxford University Press. Vol:122 (1) 1007-1008.

Sandoval, M., and Lebrun, I. (2003) TsTx Toxin isolated from Tityus serrulatus sacorpion venom induces spontaneous recurrent seizures and mossy fiber sprouting. Epilepsia Vol:42 (7) 904-911.