31 May, 2011

Reproduction in Chiromachus ochropus from Seychelles

There are too many scorpion species that we do not know anything about when it comes to their biology. because of this it is interesting to read the new paper from Lourenco, Leguin & Cloudsley-Thompson on the embryonic and post-embryonic development of Chiromachus ochropus (C. L. Koch, 1837) (Hemiscorpiidae) from Fregate Island, Seychelles.

Interestingly, this species can grow up to 120 mm i total length.

Observations have been made since the end of the 1990s on living scorpions of the species Chiromachus ochropus (C. L. Koch, 1837). These were collected by British biologists, on a field trip to Fregate Island, Seychelles. The total duration of embryonic development averaged 25 months. The moults necessary to reach the various juvenile instars and adulthood took place at average ages of 10, 242, 596, 925, 1763, 2310, 2661, 2957, 3313 and 3773 days. These developmental periods are remarkable longer than those previously observed in any other species of scorpions. Eleven instars were observed among the specimens that had been reared in captivity. This is unique among scorpions. Morphometric growth values of the different instars are significantly inferior to those in other species studied. A significantly larger size was observed in some of the females collected in the field, suggesting the occasional existence of at least one extra instar.

Lourenco WR, Leguin E-A, Cloudsley Thompson JL. The embryonic and postembryonic developments of Chiromachus ochropus (C. L. Koch, 1837) (Scorpiones, Liochelidae) from Fregate Island, Seychelles. Entomol Mitt Zool Mus Hamburg. 2011;15(184):213-22.

Thanks to Wilson Lourenco and Gerard Dupre for sending me this paper!

Family Hemiscorpiidae

27 May, 2011

Scorpion Envenomations in Mali

The knowledge about scorpion envenomations and species of medical importance in North-Africa and Southern Africa is quite good. Less is known about the status of scorpionism in Central (Sub-Saharan) Africa.

Dabo and co-workers have now published an article on scorpion envenoming in the North of Mali, increasing our knowledge on scorpions impact on health in this area. Leiurus quinquestriatus and Androctonus amoreuxi are mentioned as species involved in sting incidents, but unfortunately the involved species is unknown in 93% of the cases.

Scorpion envenomation remains a poorly known problem in sub-Saharan Africa, particularly in Mali, where the incidence is high in Northern area of the country (Sahara desert). We conducted a prospective study in two district health centers, Kidal and Tessalit (Northeast of Mali), to describe the epidemiological, clinical and therapeutic features of scorpion stings. This study consisted of an exhaustive follow-up from admission to discharge of all patients stung by scorpions. Of a total of 282 cases recorded during one year, 207 (73.4%) occurred in Kidal, and the remaining 75 (26.6%) took place in Tessalit. The annual incidence was significantly higher in Tessalit (437 cases/100 000 population/year) than in Kidal (243 cases/100,000 population/year) (p < 10-6). Two hundred two (71.6%) stings occurred inside human dwellings, 142 (50.4%) during sleeping/resting, especially in August. One hundred ninety-one (67.7%) were on the lower extremities. Nocturnal stings, 168 (59.6%), occurred more often than diurnal stings, 114 (40.4%). Most patients, 163 (57.8%), were admitted less than 1 h after being stung. Local pain at the sting site was the common primary complaint. However, moderate and severe clinical signs were significantly higher in children than in adults (p < 0.05). The death rate (3.9%) was higher in children (3.5%) than in adults (0.3%) (p ¼ 8.10-6; RR ¼ 0.90 [IC: 0.84–0.06]). Of the 22 scorpion species identified, 13 (59.1%) were Leiurus quinquestriiatus, 8 (36.4%) were Androctonus amoreuxi, and 1 (4.5%) specimen was Buthiscus bicalcaratus. From these species, L. quinquestriiatus and A. amoreuxi were responsible of stings. The medical treatment was only symptomatic, and one hundred twenty-eight (45.3%) patients received traditional remedies before seeking medical attention. Our findings suggest that scorpion stings are common in the north of Mali and are a significant threat to human health.

Dabo A, Golou G, Traoré MS, Diarra N, Goyffon M, Doumbo O. Scorpion envenoming in the North of Mali (West Africa): Epidemiological, Clinical and Therapeutic aspects. Toxicon. 2011;In Press. DOI: . 10.1016/j.toxicon.2011.05.004 .Subscription required for fulltext]

24 May, 2011

Five new anatomy picture collections in The Scorpion Files

Leonard Georg is still using his camera on new species and has made five new, detailed anatomy pictures collections of the following species:

Androctonus amoreuxi
Lychas scutilus
Parabuthus liosoma
Parabuthus villosus (black form)

Belisarius xambeui

A big thanks to Leonard for sharing these great pictures with us!!

20 May, 2011

What's the best treatment for scorpion stings

Scorpion envenomations are usually treated either by scorpion antivenin or by symptomatic treatment. There have always been a discussion on which methods is best and different studies have been inconclusive.

Fekri Abroug and co-workers have now published a meta-analysis of controlled studies on the use of antivenins in severe scorpion envenomations. Their conclusion is that there is a difference between world regions on how effective antivenins are: The effect in Old World scorpions is not proven and they do not reccoment the use of antivenins until proper RCT studies have proven their efficacy. On the contrary, studies have shown that scorpion antivenin hastens the recovery of patients stung by scorpions in Arizona.

Background Despite conflicting evidence, specific serotherapy is recommended for scorpion envenomation. Methods A meta-analysis of prospective or observational controlled studies, comparing intravenous scorpion antivenin (SAV) with control, was performed. Binary outcomes are reported as risk difference for clinical improvement and mortality rates. Analysis was performed both for the whole number of included studies and for two subgroups (set up according to the geographic origin of scorpions). Results Nine studies (four randomised controlled trials (RCTs), five observational) enrolling 687 patients were identified. Six dealt with Old World scorpions and three originated from Arizona. Overall, the rate of clinical improvement was similar in SAV treated and untreated patients (risk difference¼0.22, 95% CI -0.35 to 0.79; p¼0.45 for effect). Subgroup analysis showed favourable effects of SAV in the Arizona scorpion envenomation (risk difference¼0.53; 95% CI 0.16 to 0.91; p<0.001), and non-significant unfavourable effects in Old World scorpion envenomation (risk difference¼-0.05; 95% CI -0.28 to 0.18; p¼0.65; p¼0.003 for z-value, indicating a true heterogeneity of treatment effects). In Old World scorpion envenomation, there was no statistical difference in the risk of death in SAV treated and untreated scorpion envenomated patients (risk difference¼0.007, 95% CI -0.02 to 0.03; p¼0.6 for effect). Overall, administration of scorpion antivenin was associated with a reduction by 13 h in the mean time of symptom resolution (95% CI -17 to -9; p<0.0001). Serious adverse events were reported at a rate of 1e2% while minor adverse events occurred in up to 40% of patients. Conclusions SAV should not be administered in Old World scorpion envenomation until its efficacy is established by an appropriately designed RCT. In the Arizona scorpion sting, SAV hastens the recovery process.

Abroug F, Ouanes-Besbes L, Ouanes I, Dachraoui F, Hassen MF, Haguiga H, et al. Meta-analysis of controlled studies on immunotherapy in severe scorpion envenomation. Emerg Med J. 2011 May 11. [Subscription required for fulltext]

06 May, 2011

Yet another Vaejovis from USA

Richard Ayrey and Michael Soleglad have published a new species of Vaejovis (Vaejovidae) from Arizona, USA.

Vaejovis crumpi Ayrey & Soleglad, 2011

A new scorpion species, Vaejovis crumpi, sp. nov., is described from Prescott, Yavapai Co., Arizona. This species is related to V. paysonensis Soleglad, 1973, and the “sky island” species of southern Arizona. V. crumpi is compared to the seven Vaejovis species currently reported for Arizona, in particular to V. paysonensis.

Ayrey RF, Soleglad ME. A new species of Vaejovis from Prescott, Arizona (Scorpiones: Vaejovidae). Euscorpius. 2011(114):1-15. [Free fulltext]

Family Vaejovidae