07 January, 2009

A new medical important scorpion from Argentina

It is well known that several species in the South American genus Tityus can cause serious morbidity and even death in humans (especially in children). In Argentina, envenomation by scorpions is a increasing medical problem. The species associated with severe human envenomations have been Tityus trivittatus and T. bahiensis (at least 10 deaths are reported in the last 10 years).

Adolfo de Roodt and co-workers (2008) now report about a handful scorpion related deaths in children in the last years that have not been attributed to the above mentioned species, but to Tityus confluens. An investigation of the venom and the effects of the venom on mice confirmed the potency of the venom. A LD50 value of 0.7 mg/kg in mice is reported and this is quite low and an indication of medical importance.

Based on this study, Tityus confluens should be listed as medical important species that can cause the same degree of morbidity as Tityus trivittatus and other medical important Tityus species.

In Argentina the scorpions of medical importance belong to the genus Tityus (T.), particularly the species T. trivittatus, the only scorpion whose sting is recognized to be associated with severe human envenoming and death. This genus is distributed from the north of the Patagonian region to the center and some provinces in the north of the country. During the period 2003–2006 four children died following scorpion stings, of which one was certainly and three were probably by T. confluens. In 2006, in the province of Tucumán, a girl died by scorpion envenoming and the scorpion responsible for the death, found in her shoe, was T. confluens. We thus studied the toxicity of venom gland homogenates from T. confluens from the provinces of Jujuy and Catamarca, and of crude venom from specimens from Catamarca and the province of La Rioja. The lethal potencies of the telson homogenates were 7.0 and 18.6 μg/g for Jujuy and Catamarca, respectively, while the lethal potency of the crude venom was 0.7 μg/g. Injected mice showed generalized congestion and hepatic lesions. Pancreatic damage was observed in some animals. Lungs showed congestion and foci of hemorrhage and mild edema. The heart showed injury in the muscular fibers. The venom showed high reactivity against anti-T. trivittatus antivenom and against two anti-T. serrulatus antivenoms. The anti-T. trivittatus antivenom neutralized the lethal activity of T. confluens venom. In addition, the venom reacted very slightly against an anti-Centruroides antivenom. Therefore, the stings of this scorpion must be considered of risk for humans to the same degree as the stings of T. trivittatus.

de Roodt AR, Lago NR, Salomón OD, Laskowicz RD, Neder de Román LE, López RA, et al. A new venomous scorpion responsible for severe envenomation in Argentina: Tityus confluens. Toxicon. 2009;53(1):1-8. [Subscription required for fulltext]

Family Buthidae

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