Pregnant woman stung by Parabuthus maximus in Kenya

 

I usually do not blog all scorpion envenomation reports, but I found this one of special interest as the victim was a pregnant women and the case involved a Parabuthus Pocock, 1890 (Buthidae) species from Kenya. We know quite a lot about the consequences of Parabuthus envenomations from southern Africa, but there are fewer documented cases from East Africa.

Felix Pius Omullo recently published a case report involving a 36 week pregnant women stung by a confirmed Parabuthus maximus Werner, 1913 (Buthidae) in Kenya. Thanks to quick treatment and administration of species-specific antivenom, both the mother and the fetus improved quickly. Both mother and the baby were well two weeks after the baby was born. 

The article discusses the case and the interventions necessary in cases like this.

PS! The dark discoloration shown in the picture of the sting site on the heel is due to traditional medicine first aid using a pasty substance made of a mixture of Kiwi shoe polish and Colgate toothpaste.

Abstract:
BACKGROUND
Scorpion envenomation in pregnancy is a rare but potentially fatal obstetric emergency, with limited evidence on optimal management and antivenom safety. Neurotoxic venom induces autonomic storms, threatening maternal cardiovascular stability and uteroplacental perfusion, which can lead to fetal distress or demise.

CASE SUMMARY
A 31-year-old gravida 4, para 3 woman at 36 weeks’ gestation presented 30 minutes after a confirmed Parabuthus maximus sting to her right foot. She manifested systemic envenomation, including agitation, profuse sweating, tachycardia (142 bpm), and hypertension (168/102 mmHg). Cardiotocography revealed fetal tachycardia (175-180 bpm). A multidisciplinary team initiated intravenous morphine, midazolam, and species-specific antivenom (South African Vaccine Producers Polyvalent Scorpion Antivenom), resulting in the resolution of maternal and fetal symptoms within 12 hours. Critically, antivenom was administered within 40 minutes of the sting, which likely contributed to the rapid reversal of the catecholamine surge. A key factor enabling this rapid and targeted response was the patient’s action of capturing the scorpion, allowing for precise species identification. The pregnancy progressed uneventfully to term, culminating in an uncomplicated vaginal delivery of a healthy infant.

CONCLUSION
This case illustrates that scorpion envenomation in late pregnancy poses a dual threat to both maternal and fetal well-being. Prompt recognition, continuous fetal monitoring, and the very early administration of antivenom-buttressed by multidisciplinary care-can avert catastrophic outcomes. This case provides supporting evidence that antivenom can be safe and effective during the third trimester, even in resource-constrained environments. Public education on safe first aid, including bringing the scorpion for identification, is essential.

Reference:
Omullo FP. Successful management of third-trimester scorpion envenomation (Parabuthus maximus) in a resource-limited setting: A case report. World J Clin Cases. 2026;14(2):114762. [Open Access]

Two papers on the venom and venom effect of Tityus species in Brazil

 

As most of you know, there are several medical important scorpions in the Genus Tityus C. L. Koch, 1836 (Buthidae) in Brazil and other countries of South America. Knowledge of the venom composition of dangerous scorpions and their clinical effect is important, both for understanding how they work, but also to develop effective anti-venom therapy. In addition, studying scorpion venom is also important to see if there are components that can be used in medical research.

Last fall there was published two papers on the biochemistry and the effects of the venom of several species of Tityus (and one species of Brotheas C.L. Koch, 1837 in Chactidae). I refer to the abstracts below for further details on these studies.

Paper 1:

Abstract:
Scorpionism is a growing public health concern in Brazil, with the Amazon region presenting the highest mortality rates but remaining understudied, especially regarding local scorpion venoms composition. This study presents the first comprehensive biochemical characterization of venoms from three Amazonian species—Tityus metuendus (TmetuV), Tityus silvestris (TsilvV), and Brotheas amazonicus (BamazV)—using an integrated approach combining Multi-Enzymatic Limited Digestion (MELD)-based bottom-up proteomics, highresolution LC-MS/MS, chromatography, zymography, and enzymatic assays. Tityus serrulatus venom was included as a reference. Significant biochemical differences were observed: TsilvV was rich in 20–30 kDa proteins and showed strong metalloprotease activity; BamazV exhibited high molecular weight proteins and potent phospholipase A2 (PLA2) activity but lacked proteolytic and fibrinogenolytic activities; TmetuV showed the highest hyaluronidase activity and abundance of α-KTx neurotoxins. Zymography revealed a conserved ~45 kDa hyaluronidase in all species. Three novel components were partially characterized: BamazPLA2 (Group III PLA2), Tmetu1 (37-residue α-KTx), and TsilvMP_A (a metalloprotease homologous to antarease). This is the first application of MELD-based proteomics to Amazonian scorpion venoms, revealing molecular diversity and functional divergence within Tityus and Brotheas, emphasizing the need for region-specific antivenoms. These findings provide a foundation for future pharmacological studies and the discovery of bioactive peptides with therapeutic potential.

Reference:
Bordon KCF, Santos GC, Martins JG, Wiezel GA, Amorim FG, Crasset T, et al. Pioneering Comparative Proteomic and Enzymatic Profiling of Amazonian Scorpion Venoms Enables the Isolation of Their First α-Ktx, Metalloprotease, and Phospholipase A(2). Toxins (Basel). 2025;17(8). [Open Access]

Paper 2:

Abstract:
Scorpion stings are considered a neglected condition and represent a serious health problem in many tropical countries, especially for children and the elderly. In Brazil, the yellow scorpion (Tityus serrulatus) is widely found and responsible for the majority of severe envenoming cases; however, other medically relevant species endemic to the Brazilian Amazon region, such as Tityus silvestris, Tityus metuendus and Tityus obscurus, remain underexplored. In the present study, we characterized the clinical, inflammatory and histopathological responses induced by venoms from these Amazonian species in a murine model (Balb/c mice), using T. serrulatus as a reference. Envenomation with T. silvestris resulted in pronounced systemic manifestations, including elevated clinical scores, hyperglycemia, leukocytosis, cytokine release (IL-6, IL-1β, IL-10), and tissue injury in the lungs and kidneys, comparable to the pathophysiological manifestations from T. serrulatus venom. In contrast, T. metuendus and T. obscurus induced milder inflammatory profiles. It is noteworthy that cross-reactivity assays revealed limited immunoreactivity and reduced in vivo neutralization of T. metuendus and T. obscurus venoms by the commercially available T. serrulatus-based antivenom. These findings reveal critical limitations in relying on a single-species antivenom for treating scorpion envenomation across diverse regions and underscore the need for region-specific therapeutic strategies tailored to the distinct venom profiles and pathogenicity of Amazonian Tityus species.

Reference:
Zoccal KF, de Castro Figueiredo Bordon K, Reis MB, Rosa Nunes de Souza Chini PB, Martins JG, Zuanazzi BA, et al. Divergent clinical, inflammatory, and histopathological responses induced by Amazonian Tityus venoms: insights and limitations of current antivenom therapy. Biochimie. 2025;238(Pt B):159–71. [Subscription required for full text]

Thanks to Jonas Martins for sending me the two articles!

Scorpionism in Ecuador - An updated review

 

Scorpion envenomations are a problem in many countries in South America, but a majority of studies have focused on Brazil. A recent article by Adolfo Borges and co-workers shows that also Ecuador is a hotspot for scorpion envenomations in South America.

The study provides an overview of scorpion stings in Ecuador between 2017 and 2021 and the implications in form of deaths and morbidity. The authors also identify taxa of medical importance and their distribution. Unsurprisingly, two species in the genus Tityus C. L. Koch, 1836 (Buthidae) are probably responsible for the most serious cases.  

Abstract:
This study assessed scorpion envenoming risk in Ecuador at provincial and district levels between 2017 and 2021, estimated national incidence and mortality rates, and identified the likely implicated taxa. Data were obtained from the Ministry of Public Health and aggregated by province and district, with incidence and mortality rates calculated per 100,000 inhabitants using annual population estimates. District-level risk was visualized with choropleth maps, and scorpion diversity and distribution were compiled from updated national inventories. A total of 1,514 scorpion stings were reported between 2017 and 2021. National incidence and mortality rates (per 100,000 inhabitants) averaged 1.75 and 0.02. Regional incidence was highest in the Amazonian region (16.81), followed by the coastal (1.39) and Andean highlands (0.66). Hyperendemic districts (≥95th percentile of risk) included Taisha and Tiwintza (Morona Santiago), Arajuno (Pastaza), Flavio Alfaro (Manabí), and La Concordia (Santo Domingo de los Tsáchilas). Mortality was highest in the Amazonian and piedmont coastal regions, with 10 deaths per region and an Amazonian rate of 0.44 per 100,000 inhabitants. These areas are inhabited by Tityus species from distinct morphological and toxinological groups, notably Tityus cf. rosenbergi in western Ecuador and Tityus cisandinus in Morona Santiago and Pastaza. Geographical variation in incidence and mortality likely reflects both the distribution of noxious taxa and population density. Despite high scorpion endemicity (79.2%), a national lethality rate of 1.32% that appears higher than reported in other countries where scorpionism is a public health concern, and the concentration of fatalities in children (75% in ages 1–9), Ecuador still depends on imported scorpion antivenoms, including that prepared against Centruroides species, which show low reactivity to Tityus toxins. These findings highlight the urgent need for preclinical neutralization studies to evaluate local antivenom efficacy and to investigate regional differences in clinical outcomes, to guide future adjustments to immunotherapy based on the biogeographic distribution of medically important Tityus species.

Reference:
Borges A, De Sousa L, Borja-Cabrera GP, Rivera A. Scorpion Envenoming in Ecuador: District-Level Risk, Updated Scorpion Diversity, and Challenges for Treatment and Public Health. Acta Trop. 2025:107942 (In Press). [Subscription required for full text.]

Thanks to Adolfo Borges for informing me about their new article! 

A biochemical and proteomic study of Amazonian scorpion venoms

 

Studying the venom composition of scorpions is important. It is important to know the venom composition in medical important species to understand their pathological effect and better be able to develop antivenom or treatment. In addition, scorpion venom is a treasure chest filled with different peptides and toxins that can be used to develop medicines. 

Karla Bordon and co-workers recently published a study presenting a comprehensive biochemical characterization of venom from three Amazonian species, Tityus metuendus Pocock, 1897, T. silvestris Pocock, 1897 (both Buthidae) and Brotheas amazonicus  Lourenço, 1988 (Chactidae).

According to the article, "the results suggest a correlation between ecological divergence and venom composition, with implications for both toxicity and antivenom development".

Abstract:
Scorpionism is a growing public health concern in Brazil, with the Amazon region presenting the highest mortality rates but remaining understudied, especially regarding local scorpion venoms composition. This study presents the first comprehensive biochemical characterization of venoms from three Amazonian species—Tityus metuendus (TmetuV), Tityus silvestris (TsilvV), and Brotheas amazonicus (BamazV)—using an integrated approach combining Multi-Enzymatic Limited Digestion (MELD)-based bottom-up proteomics, highresolution LC-MS/MS, chromatography, zymography, and enzymatic assays. Tityus serrulatus venom was included as a reference. Significant biochemical differences were observed: TsilvV was rich in 20–30 kDa proteins and showed strong metalloprotease activity; BamazV exhibited high molecular weight proteins and potent phospholipase A2 (PLA2)
activity but lacked proteolytic and fibrinogenolytic activities; TmetuV showed the highest hyaluronidase activity and abundance of α-KTx neurotoxins. Zymography revealed a conserved ~45 kDa hyaluronidase in all species. Three novel components were partially characterized: BamazPLA2 (Group III PLA2), Tmetu1 (37-residue α-KTx), and TsilvMP_A (a metalloprotease homologous to antarease). This is the first application of MELD-based proteomics to Amazonian scorpion venoms, revealing molecular diversity and functional divergence within Tityus and Brotheas, emphasizing the need for region-specific antivenoms. These findings provide a foundation for future pharmacological studies and the discovery of bioactive peptides with therapeutic potential.

Reference:
Bordon KC, Santos GC, Martins JG, Wiezel GA, Amorim FG, Crasset T, et al. Pioneering Comparative Proteomic and Enzymatic Profiling of Amazonian Scorpion Venoms Enables the Isolation of Their First α-Ktx, Metalloprotease, and Phospholipase A2. Toxins. 2025;17(8):411. [Open Access]

Thanks to Jonas Martins for sending me their article!

Molecular study of medical important Hemiscorpius species from Iran

 

Correct identification of medical important scorpions is very important to be able to provide optimal treatment. Many species are morphological similar and this will make correct identification difficult. This is the case with many species of Hemiscorpius  Peters, 1861 (Hemiscorpiidae) in Iran. 

Shahi and Barahoei have recently published a molecular study on the Hemiscorpius fauna in the Hormozgan province in southern Iran. The study confirms the validity of the following three species in the genus:

Hemiscorpius acanthocercus Monod & Lourenço, 2005
Hemiscorpius enischnochela Monod & Lourenço, 2005
Hemiscorpius lepturus Peters, 1861

This is important information as the available antivenom for this genus do not work optimal inn all cases and this might be because there are different species involved. 

Abstract:
Three species of Hemiscorpius were identified in Hormozgan province, for which the available antivenoms lack the efficacy required for treating patients. Consequently, an exact identification of the existing species was deemed necessary as the first step in managing treatment procedures. Considering the morphological similarities among the species, the aim of this research was the molecular study of the samples to accurately identify the species. Hemiscorpius specimens were collected from various locations in Hormozgan province between 2021 to 2023. The Cytochrome c oxidase subunit I gene was amplified and sequenced. Four sequences were obtained from Hemiscorpius specimens collected from Hormozgan province, and three sequences were sourced from the NCBI for analysis. Bayesian inference and Maximum likelihood phylogenetic trees showed similar results, positioning the base of Hemiscorpius enischnochela tree as an older species and Hemiscorpius lepturus adjacent to Hemiscorpius acanthocercus, identified as the newest species at the tree's tip. The results confirmed the validity of three species, namely H. acanthocercus, H. enischnochela, and H. lepturus. Hemiscorpius acanthocercus and H. lepturus are known for having dangerous venom for humans with reported deaths due to their stings. Considering the importance of the members of this genus from the medical point of view, a comprehensive examination of all species is imperative.

Reference:
Shahi M, Barahoei H. Molecular study of Hemiscorpius Peters (Scorpiones: Hemiscorpiidae) in Hormozgan province, South of Iran. Arch Razi Inst. 2024;79(1):211-7. [Open Access]

Family Hemiscorpiidae

A study on the relative efficacy of three antivenoms against medically significant Centruroides species from Mexico

 

Mexico is a hot spot for medical important scorpions and at least 21 species from the Centruroides Marx, 1890 (Buthidae) genus cause a large number of serious envenomations every year. Good treatment options is important and using antivenom is one of the most important tool.

Sam Campbell and co-workers have recently published a study looking into the ability of three  antivenoms to neutralize the activity of the venoms of several Centruroides species. One important result from this study is that the truly “broad” neutralization capacity of the antivenoms can be questioned as there were variations in the neutralization of several medical important Centruroides species (even though the venom of these were included in the antivenoms).

The author also stress the importance of proper laboratory studies and methods for studying the effects of antivenom candidates.

Abstract:
In this study, we report the innovative application of whole-cell patch-clamp electrophysiology in assessing broad-spectrum neutralisation by three different antivenoms, of venoms from the medically significant scorpion genus Centruroides. Envenomations by as many as 21 species from the Centruroides genus result in up to 300,000 envenomations per year in Mexico, which poses significant and potentially life-threatening pathophysiology. We first evaluated the in vitro manifestation of envenomation against two human voltage-gated sodium (hNaV) channel subtypes: hNaV1.4 and hNaV1.5, which are primarily expressed in skeletal muscles and cardiomyocytes, respectively. The neutralisation of venom activity was then characterised for three different antivenoms using a direct competition model against the more potent target, hNaV1.4. While broad-spectrum neutralisation was identified, variation in neutralisation arose for Centruroides elegans, C. limpidus, C. noxius and C. suffusus venoms, despite the presence of a number of these venoms within the immunising mixture. This raises questions regarding the truly “broad” neutralisation capacity of the antivenoms. This study not only extends previous validation of the in vitro investigation of antivenom efficacy utilising the whole-cell patch-clamp technique but also underscores the potential of this animal-free model in exploring cross-reactivity, experimental scalability, and most importantly, informing clinical management practices regarding the administration of antivenom in Mexico.

Reference:
Campbell SID, Chow CY, Neri-Castro E, Alagón A, Gómez A, Soria R, et al. Taking the sting out of scorpions: Electrophysiological investigation of the relative efficacy of three antivenoms against medically significant Centruroides species. Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology. 2024;283:109977. [Open Access]

Thanks to Jeroen Kooijman for informing me about this article!

New insight into venom composition in Tityus melici and related medical important Tityus species

 

 Yan Kalapothakis and co-workers recently published a study of the venom composition of the medical important Brazilian scorpion Tityus melici Lourenço, 2003 (Buthidae). This species is morphologically related to Tityus serrulatus Lutz & Mello, 1922, which is the most medically significant species in Brazil.

Dr. Adolofo Borges, who is one of the authors, has kindly summed up the results of this study for me: "The article presents evidence indicating that venom from Tityus melici, a species belonging to the "Tityus stigmurus" complex, exhibits divergence in toxin antigenicity and enzyme content/activity with respect to Tityus serrulatus using transcriptomic and biochemical approaches. The antivenom prepared in Brazil against T. serrulatus (also within the "stigmurus" group) only partially neutralizes toxicity of this venom, suggesting toxin divergence among these closely related species."

This type of knowledge is very useful when it comes to how to handle and treat serious scorpionism involving these species in Brazil.

Abstract:
The Brazilian scorpion Tityus melici, native to Minas Gerais and Bahia, is morphologically related to Tityus serrulatus, the most medically significant species in Brazil. Despite inhabiting scorpion-envenomation endemic regions, T. melici venom remains unexplored. This work evaluates T. melici venom composition and function using transcriptomics, enzymatic activities, and in vivo and in vitro immunological analyses. Next-Generation Sequencing unveiled 86 components putatively involved in venom toxicity: 39 toxins, 28 metalloproteases, seven disulfide isomerases, six hyaluronidases, three phospholipases and three amidating enzymes. T. serrulatus showed the highest number of toxin matches with 80–100 % sequence similarity. T. melici is of medical importance as it has a venom LD50 of 0.85 mg/kg in mice. We demonstrated venom phospholipase A2 activity, and elevated hyaluronidase and metalloprotease activities compared to T. serrulatus, paralleling our transcriptomic findings. Comparison of transcriptional levels for T. serrulatus and T. melici venom metalloenzymes suggests species-specific expression patterns in Tityus. Despite close phylogenetic association with T. serrulatus inferred from COI sequences and toxin similarities, partial neutralization of T. melici venom toxicity was achieved when using the anti-T. serrulatus antivenom, implying antigenic divergence among their toxins. We suggest that the Brazilian therapeutic scorpion antivenom could be improved to effectively neutralize T. melici venom.

Reference:
Kalapothakis Y, Miranda K, Aragão M, Larangote D, Braga-Pereira G, Noetzold M, et al. Divergence in toxin antigenicity and venom enzymes in Tityus melici, a medically important scorpion, despite transcriptomic and phylogenetic affinities with problematic Brazilian species. Int J Biol Macromol. 2024;263:130311. [Subscription required for full text]

Thanks to Dr. Borges for informing me about the new article and for summing up the results for me!

Venom composition in the medical important scorpion Leiurus abdullahbayrami from The Middle East

 

The 23 species in the genus Leiurus Ehrenberg, 1828 (Buthidae) have the most potent venom of all scorpions and posing a medical threat to humans in their area of distribution. Knowledge of the venom composition and potency of the different species is important for correct treatment and the use of antivenom.

Adolfo Borges and Bruno Lomonte have recently published a study of the venom composition of Leiurus abdullahbayrami Yagmur, Koc & Kunt, 2009, distributed in Turkey, Syria, and Lebanon. This species have been involved in serious envenomations and this study confirms the potency of its venom. 

The study also found that the venom composition in Leiurus abdullahbayrami and other species vary and more research on this potential interspecific variation is necessary to decide whether a species-specific antivenom is necessary for sting cases involving this species.

Abstract:
The scorpion Leiurus abdullahbayrami has been associated with severe/lethal envenomings throughout the Levant region of the Middle East, encompassing Turkey, Syria, and Lebanon, and only scarce information is available on its venom composition, activity, and antigenicity. We report on the composition of L. abdullahbayrami venom collected from Lebanese specimens using nESI-MS/MS, MALDI-TOF MS, SDS-PAGE and RP-HPLC. Venom lethality, through LD50 determination in mice (intraperitoneal), was also assessed (0.75 (0.16–1.09) mg/kg), confirming L.abdullahbayrami venom vertebrate toxicity. Fifty-four peaks were detected using RP-HPLC, half of which eluted in the gradient region between 20 and 40% acetonitrile. In reducing SDS-PAGE, most predominant components were <10 kDa, with minor components at higher molecular masses of 24.4, 43.1, and 48.9 kDa. Venom mass fingerprint by MALDI-TOF detected 21 components within the 1000–12,000 m/z range. Whole venom ‘shotgun’ bottom-up nLC-MS/MS approach, combined with in-gel tryptic digestion of SDS-PAGE bands, identified at least 113 different components belonging to 15 venom families and uncharacterized proteins, with ion channel-active components (K+ channel toxins (28); Na+ channel toxins (42); Cl􀀀 channel toxins (4); Ca+ toxins (2)) being predominant. A single match for a L. adbullahbayrami NaTx was found in the UniProt database with other congeneric species, toxin h3.1 from Leiurus hebraeus, suggesting this might be an indication of venom divergence within Leiurus, eventhough this warrants further investigation involving venom proteomics and transcriptomics of relevant species. Considering such potential interspecific venom variation, future work should address whether preparation of a specific anti-L. abdullahbayrami antivenom is justified.

Reference:
Borges A, Lomonte B. Venomics of Leiurus abdullahbayrami, the most lethal scorpion in the Levant region of the Middle East. Toxicon. 2024;237:107548. [Subscription required for full text]

Thanks to Luis A. Roque for informing me about this article!

Common toxin components among different Tityus species in the Amazon region may lead to a common therapeutic strategy

 

Scorpionism is a major problem in many parts of the world, and for the Amazon Region in South America several Tityus C. L. Koch, 1836 species (Buthidae) are known to cause severe morbidity or even deaths. The problem is that there is no effective antivenom currently available in this region.

Identifying the different toxin components of the venom of different Tityus species may lead to the development of new therapeutics.Yan Kalapothakis and co-workers have recently published a study analysing the venom of the medical important species Tityus cisandinus Lourenço & Ythier, 2017 and comparing it to the venom of another medical imprtant species T. obscurus (Gervais, 1843).

Interestingly, they found a high similarity between T. cisandinus and T. obscurus venoms. This is important knowledge that can be used to create a "common therapeutic strategy (i.e production of a region-specific antivenom) to tackle the increasing burden of scorpionism in Amazonia" [Adolfo Borges, personal communication].

Abstract:
Tityus cisandinus, a neglected medically important scorpion in Ecuadorian and Peruvian Amazonia, belongs to a complex of species related to the eastern Amazon endemic Tityus obscurus, spanning a distribution of ca. 4000 km. Despite high morbidity and mortality rates, no effective scorpion antivenom is currently available in the Amazon region. Knowledge of the structural/functional relationships between T. cisandinus venom components and those from related Amazonian species is crucial for designing region-specific therapeutic antivenoms. In this work, we carried out the first venom gland transcriptomic study of an Amazonian scorpion outside Brazil, T. cisandinus. We also fingerprinted its total venom through MALDI-TOF MS, which supported our transcriptomic findings. We identified and calculated the expression level of 94 components: 60 toxins, 25 metalloproteases, five disulfide isomerases, three amidating enzymes, one hyaluronidase, and also uncovered transcripts encoding novel lipolytic beta subunits produced by New World buthid scorpions. This study demonstrates the high similarity between T. cisandinus and T. obscurus venoms, reinforcing the existence of a neglected complex of genetically and toxinologically related Amazonian scorpions of medical importance. Finally, we demonstrated the low recognition of currently available therapeutic sera against T. cisandinus and T. obscurus venoms, and concluded that these should be improved to protect against envenomation by Amazonian Tityus spp.

Reference:
Kalapothakis Y, Miranda K, Molina DAM, Conceição I, Larangote D, Op den Camp HJM, et al. An overview of Tityus cisandinus scorpion venom: Transcriptome and mass fingerprinting reveal conserved toxin homologs across the Amazon region and novel lipolytic components. Int J Biol Macromol. 2022. [Subscritpion required for full text]

Thanks to Adolfo Borges for informing me about this article!

What is the best treatment for scorpion envenomations?

Scorpions are still a significant cause for mortality, especially in developing countries. The are several treatment strategies available for serious scorpion stings. Some involves the use of anti-venom, while others are based on symptomatic treatment. Studies so far has shown that one treatment strategy works for some species, but are less effective for others.

Rodrigo and Gnanathasan have recently published a systematic review on scorpion envenomations trying to find the best evidence available for the efficiency of the different treatment strategies used against serious scorpion envenomation around the world.

The main conclusion is that the polyvalent antivenom against Centruroides sp. in USA/Mexico and the monovalent antivenom against Hottentotta tamulus in India are effective for rapid resolution of symptoms. Prazosin is useful as an add-on therapy for H. tamulus stings. I recommend reading the article for further details.

Abstract:
Background: Scorpion stings cause an estimated 3000 deaths per annum worldwide. We conducted a systematic review of all controlled clinical trials related to scorpion sting management.
Methods: We searched PubMed, EMBASE, Scopus, Web of Science and CINAHL and included controlled prospective clinical trials (randomized or non-randomized). The following interventions were assessed: adults and children with scorpion stings treated with (a) steroids vs. placebo, (b) different methods of pain relief, (c) antivenom vs. supportive treatment, (d) prazosin vs. supportive treatment, (e) antivenom vs. prazosin and (f) antivenom plus prazosin vs. prazosin alone. When trials had comparative outcomes, they were combined in a meta-analysis. Data was analysed with Review Manager 5. Dichotomous data were compared with relative risk (RR), and continuous data were compared with mean differences using a fixed effect model. There is no PROSPERO registration number for this study.
Results: Antivenom against Centruroides sp. are effective in reversing the clinical syndrome faster than no antivenom treatment in children (RR, 0.02; 95% CI, 0.01 to 0.06; 322 participants; three trials). Antivenom (against Mesobuthus tamulus) and prazosin combination is better than prazosin alone for faster resolution of symptoms (mean difference, −12.59 h; 95% CI, −14.01 to −11.17; 173 participants; three trials).
Conclusions: The polyvalent antivenom against Centruroides sp. in USA/Mexico and the monovalent antivenom against M. tamulus in India are effective for rapid resolution of symptoms. Prazosin is useful as an add-on therapy for M. tamulus stings.

Reference:
Rodrigo C, Gnanathasan A. Management of scorpion envenoming: a systematic review and meta-analysis of controlled clinical trials. Systematic Reviews. 2017;6(1):74. [Open Access]

A major reference book on scorpion venoms and scorpionism

Last Fall a major reference book on scorpion venoms and scorpionism around the world was published. I haven't read this book yet, but I will later and I plan to post information about the most interesting chapters in the blog. Unfortunately, the book is very expensive to purchase (unless your university has a Springer ebook subscription).

Information about the book Scorpion Venoms from Springer

The publisher has the following information about the content of the book:

• Provides accessible yet in-depth entries on the state of the art of scorpion venom research
• Introduces scorpion biology and ecology and covers studies of their venom and “anti-venoms”
• Contains species-centered overviews and examines the scorpion toxins
• Explores the complex interactions of scorpion venoms with the immune system

Scorpions have fascinated humans for a long time, first and foremost because of the harm the sting of a few species could cause but also due to their unique natural history and for the many biologically active compounds found in their venoms. This volume of the Toxinology handbook series covers all those aspects. The subjects are divided into seven sections starting with an introduction to the general aspects of scorpion biology and ecology, followed by the description of the “envenomation” pathophysiology, pharmacokinetics, and pharmacodynamics of venoms and their complex interactions with the immune system. The future of anti-scorpion venom therapy is then covered in two chapters dedicated to alternatives to the century-old techniques currently used to produce “anti-venoms”. The next section presents a world tour of “scorpionism” and dangerous scorpion species and their impact on human health. It is worth remembering that envenomation due to scorpion stings is a substantial health hazard in Asian, Middle Eastern, African, and Latin American countries, with over one million people stung by scorpions every year, resulting in more than 3,000 deaths. Species-centered overviews of “scorpion venoms” are presented in the next section, after which a section details the two main types of “scorpion toxins”. The last section covers high-throughput transcriptome and proteome screenings now known as “venomics”.

Reference:
Gopalakrishnakone P, Possani LDF, Schwartz E, Rodríguez de la Vega RC, editors. Scorpion Venoms. Dordrecht: Springer; 2014. [Subscritpion is required for access to the full text of the book]

Thanks to Dr. Adolfo Borges for sending me a copy of his chapter in the book and thereby notifying me about this book!

The history of scorpion antivenom in North America

Leslie Boyer has written a very interesting article on the history of scorpion antivenom. The paper's main focus is North America, but main globale events in the history of scorpion antivenom and treatment are also presented.

Abstract:
This paper was originally presented as the Elsevier Lecture in July, 2012 at the International Society on Toxinology/Venom Week combined meeting in Honolulu, Hawaii. In it, the author addresses the ancient history of venom and immunity, from the Silurian Era to the 1890s; the development of the first antivenoms; the impact of shifting political and economic pressures; the special case of Arizona; the relative stability of the 1960s through 1990s; the transition to regulatory compliance that took place at the time of the author’s own research; and concluding thoughts regarding the instability of apparent success.

Reference:
Boyer L. History of scorpion antivenom: One Arizonan's view. Toxicon. 2013;69:14-20. [Subscription required for full text]

Scorpion envenomation in children in the United States

Skolnik and Ewald have recently published a review on scorpion stings involving children in USA. The only potential dangerous species in USA is Centruroides sculpturatus Ewing, 1928 (Buthidae). Even though only one deaths has been reported in the literature since 1970 (and this was probably an allergic reaction), there is no doubt that C. sculpturatus may cause serious morbidity in children. The current paper is important in summing up current knowledge and treatment of scorpion envenomations in USA.

Abstract:
In the Southwestern United States, the venom of the scorpion Centruroides sculpturatus (common name bark scorpion) can cause serious and potentially fatal neurotoxicity, with young children most vulnerable to its effects. Historically, advances in the quality of supportive care have made significant improvements in morbidity and mortality. In recent years, the development of effective antivenom therapies has changed the landscape of caring for these patients. This article reviews the background, pathophysiology, diagnosis, and treatment options for C. sculpturatus envenomation. Recent advances in immunotherapy and subsequent implications for pediatric emergency care providers are discussed.

Reference:
Skolnik AB, Ewald MB. Pediatric scorpion envenomation in the united states: Morbidity, mortality, and therapeutic innovations. Pediatr Emerg Care. 2013 January 2013;29(1):98-103. [subscription required for full text]

A updated review on the treatment of scorpion envenomations

Jean-Philippe Chippaux has recently published an updated review on the options for treating scorpion envenomations. On average 1.5 million envenomations happen worldwide every year, causing 2600 deaths. Updated information about the treatment of scorpin stings is therefore very important.

The objective of this review is to update knowledge on the management of scorpion stings and treatment of scorpion envenomings, to discuss the advantages and limitations of early immunotherapy versus medical resuscitation, and to offer a standardized management plan based on a combination of both strategies.

Abstract:
Scorpion stings are common in many tropical countries. Although most scorpion stings cause only localized pain without life-threatening envenoming, about one third of stings cause systemic envenoming which can result in death. Children are particularly sensitive to scorpion envenoming. The severity of scorpion stings is related to the presence of neurotoxins in the venom that cause a sudden release of neurotransmitters from the autonomic nervous system, predominantly sympathetic. There is also a strong inflammatory response that worsens symptoms, including those of a respiratory nature. Several vital functions may be directly affected, including the cardiovascular, respiratory, and neuromuscular systems. Hypertension is constant at the beginning of systemic envenoming and sometimes has a severe cardiac and respiratory impact. Although controversial, immunotherapy is the only etiological treatment. Administered early, it prevents many complications and improves the outcome. New antivenoms are highly purified immunoglobulin fragments, the efficacy and safety of which are excellent. As a consequence, adverse reactions to antivenoms are now very rare and usually mild, which should limit any reluctance regarding their routine use. Symptomatic treatment is still necessary to support immunotherapy, especially in cases of delayed arrival at hospital. A combination of both approaches should be considered, based on local resources and constraints.

Reference:
Chippaux JP. Emerging options for the management of scorpion stings. Drug Des Devel Ther. 2012 03 Jul;6:165-73. [Free full text]

Scorpions of medical importance in Mali

Max Goyffon and co-workers have recently published an interesting article about potential medical important scorpions in Mali. Little is known about the venom potential of species in this regions so this is an important contribution to our knowledge of African scorpionism.

Androctonus amoreuxi (Audouin, 1826), A. australis (Linnaeus, 1758) and Leiurus quinquestriatus (Ehrenberg, 1828) in the family Buthidae are identified as medical important in Mali.

Abstract:
Although the main Malian scorpion species of medical interest, Androctonus amoreuxi, is responsible for severe envenomings and perhaps some deaths, it has hitherto been considered not dangerous for humans. This population is located in the Saharian North-Eastern regions of Mali where it is accompanied by Leiurus quinquestriatus, a well known dangerous species of the Sahara. In the Gao district, divided by the Niger River, less desolate than the Tessalit and Kidal regions, one specimen of the dangerous species Androctonus australis was found. To summarize, Mali harbors at least three dangerous scorpion species: Leiurus quinquestriatus, Androctonus amoreuxi and A. australis, the latter recently having been identified in Mali for the first time. The absence of Androctonus aeneas is surprising in this context because it is found in neighboring countries (Algeria, Niger) and should be detected by new surveys. The possibility of preparing a single scorpion antivenom intended for Saharian and sub-Saharian populations is discussed.

Reference:
Goyffon M, Dabo A, Coulibaly SK, Togo G, Chippaux JP. Dangerous scorpion fauna of Mali. J Venom Anim Toxins Incl Trop Dis. 2012;18(4):361-8. [Free full text]

Clinical course of Centruroides sculpturatus envenomations managed without antivenom

In 2004, most supplies of the antivenom used to treat serious cases of Centruroides sculpturatus sting in the southwestern USA was exhausted, and supportive care and interventions became the only option available. Ayrn O'Connor and Anne-Michelle Ruha have now published a study showing the clinical course of Bark scorpion envenomations managed without antivenom.

The results show that treatment without antivenom are effective without antivenom, but 24 % of 88 patients (mainly children between 2 and 9 years) experienced respiratory failure and needed intubation. No mortality occurred, but this study show that C. sculpturatus is a dangerous scorpion for young children (and not only infants and toddlers).

In August 2011, a new antivenom for Centruroides was approved by FDA after studies showing it being effective in the treatment for serious cases. Unfortunately, this treatment is very expensive, and may force doctors and/or patients to limit the use. O'Connor & Ruha therefor highlight the importance of supportive treatment of severe scorpions stings.

Abstract:
Bark scorpion envenomation is potentially life threatening in children and traditionally treated with antivenom (AV). We sought to describe the clinical course, management, complications and outcome of children with severe scorpion envenomation treated with supportive care during a period when AV was unavailable. A retrospective chart review was performed, all children presenting to a referral hospital between September 1, 2004 and July 31, 2006 with severe scorpion envenomation not receiving AV, were included. A standardized data abstraction form was used to record time of symptom onset, time to healthcare facility (HCF), clinical findings, treatment, complications, and length of stay. Eighty-eight patients were included with mean age of 3.7 years (0.33–12). Mean time to symptom onset was 20 min (0–130) and mean time to HCF was 79 min (10–240). Incidence of clinical manifestations include: neuromuscular agitation, 100 %; opsoclonus, 97 %; hypersalivation, 81 %; tachycardia, 82 %; hypertension, 49 %; vomiting, 38 %; fever, 28 %; respiratory distress, 33 %; and hypoxia, 18 %. Complications included rhabdomyolysis in 18 (20 %) and aspiration in 12 (13 %) patients. Intubation was required in 24 % of patients. The most frequently used agents to control symptoms were benzodiazepines (98 %) followed by opioids (69 %). Intravenous fluids were given to 84 %. Mean length of stay was 29 h (range, 6–73 h). There were no deaths. In addition to the classic findings of neuromuscular hyperactivity, opsoclonus, and hypersalivation, a high incidence of hyperadrenergic findings and respiratory compromise are noted in this series. A significant number of patients required mechanical ventilation. Benzodiazpines and opioids were the most common medications used to control symptoms.

Reference:
O'Connor A, Ruha AM. Clinical Course of Bark Scorpion Envenomation Managed Without Antivenom. Journal of Medical Toxicology. 2012. Epub 2012/05/09. [Subscription required for full text]

Experimental Mexican antivenom seems to be effective in treating critically ill children after Centruroides sting in USA

Many peoples get stung by scorpions in North America every year, especially in Mexico. Most cases cause mild symptoms, but moderate and serious symptoms are also observed, especially in children. In Arizona (USA), appr. 200 cases of severe scorpion envenomation are seen each year. The involved scorpion is the buthid Centruroides sculpturatus (previous in synonymy with C. excilicauda).

Between 1965 and and 1999, a goat derived antivenom was available in Arizona. The use of this product was controversial for many years and the drug was never FDA approved. Around 2005, there was no antivenom available in Arizona for serious sting cases.

In Mexico, a new antivenom has been commersically available. The antivenom has been produced using the venom of several Mexican species causing serious morbidity. Presently, this drug is not approved by the FDA.

Leslie Boyer and co-workers have now published a randomized, double-blind study showing a positive clinical effects of the antivenom compared to the use of plasebo medicine in children with severe neurotoxic symptoms after Centruroides envenomations. Also, no serious adverse effects of the use of antivenom were observed.

Abstract:
Background: Clinically significant scorpion envenomation by Centruroides sculpturatus produces a dramatic neuromotor syndrome and respiratory insufficiency that often necessitate intensive supportive care. We hypothesized that a scorpion-specific F(ab')2 antivenom would promptly resolve clinical symptoms in children with this syndrome.
Methods: In a randomized, double-blind study, the efficacy of scorpion-specific F(ab')2 antivenom, as compared with placebo, was assessed in 15 children 6 months to 18 years of age who were admitted to a pediatric intensive care unit with clinically significant signs of scorpion envenomation. The primary end point was the resolution of the clinical syndrome within 4 hours after administration of the study drug. Secondary end points included the total dose of concomitant midazolam for sedation and quantitative plasma venom levels, before and after treatment.
Results: The clinical syndrome resolved more rapidly among recipients of the antivenom than among recipients of placebo, with a resolution of symptoms in all eight antivenom recipients versus one of seven placebo recipients within 4 hours after treatment (P=0.001). More midazolam was administered in the placebo recipients than in the antivenom recipients (mean cumulative dose, 4.61 vs. 0.07 mg per kilogram of body weight; P=0.01). Plasma venom concentrations were undetectable in all eight antivenom recipients but in only one placebo recipient 1 hour after treatment (P=0.001).
Conclusions: Among critically ill children with neurotoxic effects of scorpion envenomation, intravenous administration of scorpion-specific F(ab')2 antivenom resolved the clinical syndrome within 4 hours, reduced the need for concomitant sedation with midazolam, and reduced the levels of circulating unbound venom. (ClinicalTrials.gov number, NCT00685230 .)

Reference:
Boyer LV, Theodorou AA, Berg RA, Mallie J, the Arizona Envenomation Investigators, Chavez-Mendez A, et al. Antivenom for Critically Ill Children with Neurotoxicity from Scorpion Stings. N Engl J Med. 2009 May 14, 2009;360 (20):2090-8. [Free fulltext]

Family Buthidae