Scorpionism and Dangerous Species of Colombia
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Scorpionism is the disease caused in human beings by a scorpion sting. Depending on the severity of the sting, it can produce multiorgan system failure and death and is a public health problem worldwide with a high incidence and varying degrees of severity. But that in Colombia is a neglected health problem. The lack of awareness of the risks connected with scorpion accidents in Colombia has brought as a consequence the underestimation of this type of accident from the person who suffers it to the health professionals themselves. This too is worryingly reflected in the forming of mistaken diagnoses, in the administering of inadequate therapeutic measures, and in the lack of government programs aimed at preventing it. The systemic clinical symptoms associated with the envenomation caused by Colombian scorpions have been observed in some experimental studies, reports, series of cases, and observational studies and are related to processes of neurotoxicity, characterized by hyperactivity and intense and persistent depolarization of the autonomic fibers with the consequent massive release of neurotransmitters. These elements have been described previously for other species of scorpion of medical importance worldwide, such as Leiurus quinquestriatus, Androctonus australis, Tityus serrulatus, T. discrepans, and Centruroides exilicauda, among others. Severe scorpionism in Colombia is caused not only by T. pachyurus but also by seven species C. edwardsii, C. margaritatus, T. asthenes, T. forcipula, T. fuhrmanni, T. pachyurus, and T. n. sp. aff. metuendus, and the scorpion T. columbianus is ranked as a dangerous species.
KeywordsMedical Importance Right Bundle Branch Blockage Scorpion Venom Scorpion Sting Venomous Animal
Scorpionism is the disease caused in human beings by a scorpion sting. Depending on the severity of the sting, it can produce multiorgan system failure and death (Chippaux and Goyffon 2008; Khattabi et al. 2011). The severity of the scorpion accident or the scorpionism depends on a number of factors including the species of scorpion, the aggressiveness of the scorpion that may lead to a number of simultaneous stings, the capacity for production of venom in its gland, the amount and concentration of venom injected, and the age and individual response of the victim (Inceoglu et al. 2003; Chippaux and Goyffon 2008; D’Suze et al. 2011).
Scorpions – known in Latin America as alacranes – are a species-rich group; there are currently 15 known families of scorpions around the world, containing about 1900 described species, in which the family Buthidae is the most diverse with 87 genera and 919 species. The scorpion species with the most powerful venom belong to this family, and they are liable to cause severe to fatal scorpionism in humans (Stockmann and Ythier 2010). In Latin America, the family Buthidae has two genera of scorpion responsible for severe scorpionism, the genus Tityus with about 130 species and the genus Centruroides with 46 (Fet et al. 2000). In Colombia, the family Buthidae comprises five genera: Ananteris with 13 species, Centruroides with four species, Microtityus with two species, Rhopalurus with a single species, and Tityus with 30 species (Flórez 2001; Lourenço 2002; Botero-Trujillo and Fagua 2007; Botero-Trujillo et al. 2009; Botero-Trujillo and Flórez 2011; de Armas et al. 2012).
However, research on scorpionism, the toxinology of scorpion venom, and scorpion biology and taxonomy in Colombia is scarce, with much of the literature still unpublished (relating to undergraduate or master’s theses in biology and medicine). The present work seeks to raise awareness about the realities of scorpionism, the medical treatments applied, and the particularly dangerous species and to bring into the light what little research has been done on this topic in Colombia.
Scorpionism in Colombia
Scorpionism is a public health problem worldwide with a high incidence and varying degrees of severity. Nevertheless, research on the biology, geographical distribution, ecology, and the toxinology of scorpion venom in Colombia is only starting to emerge. This has a direct impact on lack of knowledge of the effects caused by the envenomation following a sting from scorpion species with a geographical distribution in this country.
It is worth pointing out that only from 2008 does Colombia appear on the global list of countries affected by severe scorpionism (Chippaux and Goyffon 2008), caused mainly by the Tityus pachyurus species (Barona et al. 2004; Otero et al. 2004).
The lack of awareness of the risks connected with scorpion accidents in Colombia has brought as a consequence the underestimation of this type of accident from the person who suffers it to the health professionals themselves, causing underreporting of this disease. This too is worryingly reflected in the frequency of mistaken diagnoses, in the administering of inadequate therapeutic measures, and in the lack of government programs aimed at preventing, recording, and improving the medical care of patients suffering scorpionism in Colombia.
In the first paper on scorpionism, work made by Marinkelle and Stahnke (1965), with the Centruroides margaritatus scorpion venom from Cali at Colombian southwestern, the authors reported that the most common and important symptoms observed in a retrospective study of 820 medical records and direct observation of 31 patients envenomed were pain, local edema, and fever 1–20 h after the sting; people working indoors and people of the age group 4–20 years are stung most frequently. They determined that this venom presents low toxicity for mice, with an LD50 of 59.9 mg/kg.
In the late 1990s, Pineda and Castellanos (1998) conducted a retrospective study of 25 cases of scorpionism treated in 1994 in the San Rafael Hospital in Girardot, Cundinamarca, in central Colombia, in which they showed that accidents are most frequent during the night (73 %) and in women (56 %). The parts of the body most commonly affected are the limbs, upper (30 %) and lower (35 %). Medical treatments were not the most appropriate, being limited to antihistamines (88 %), corticosteroids (32 %), and adrenaline (32 %). In the same year in northwestern Colombia – in Chigorodó, Antioquia – the death of a child under 4 years of age by cardiorespiratory arrest as a result of severe scorpionism was recorded. The same paper also highlights that children under 10 years of age are the section of the population at greatest risk of systemic poisoning (Otero et al. 1988).
Efforts to better understand the problem of scorpionism continue and are already in the first decade of 2000. Otero et al. (2004) determined the clinical and epidemiological characteristics of the scorpion accident in two departments of Colombia – in Antioquia, located in northwest, and Tolima in the midland of the country. Over the course of a year, 129 cases were studied (51 in Antioquia and 78 in Tolima): 41 cases were in children under 15 years of age with 70.5 % of sting occurring inside houses; 51 cases were caused by the scorpion T. pachyurus, 31 by Centruroides gracilis, 29 by T. fuhrmanni, seven by T. asthenes, and one by Chactas spp; and 10 cases with no causative species were identified. Systemic poisoning was significantly more common in children than in adults. The overall calculated incidence for this study was of 4.5 cases per 100,000 inhabitants and is significantly higher in Tolima (12.5/100,000 h in Tolima and 2.3 cases per 100,000 h in Antioquia).
Records of cases of scorpionism are sadly lacking. It is nevertheless quite clear that the T. pachyurus, T. asthenes, T. fuhrmanni, and C. gracilis species found in central northwestern Colombia all cause serious accidents in humans (Gómez and Otero 2007). In the Mutatá region (Antioquia), the epidemiological, clinical, and toxinological aspects of the T. asthenes scorpion were analyzed based on interviews which were carried out among the local population by Gomez et al. (2010). Of the 80 scorpionism cases, only 14 people (17.5 %) went to the hospital. Systemic poisoning was more common in children, who were featured in 67 % of cases. The venom of T. asthenes was neutralized with antivenom imported from Mexico and Brazil.
The geographical complexity in Colombia ensures that cases of scorpionism have a wide geographical and altitudinal distribution. Accidents caused by T. asthenes occur between 0 and 500 m above sea level (masl) on the Pacific coast for the departments of Antioquia, Cauca, Chocó, Nariño, and Valle del Cauca; scorpionism from T. columbianus (2,200–3,000 m) causes accidents in the Magdalena River basin between the Central and Eastern cordilleras, including the Cundiboyacense high plains in the departments of Boyacá, Cundinamarca, and Santander, as well as in Bogotá, DC; T. forcipula (1,200–2,000 m) causes accidents in Cauca River basin between the Central and Western cordilleras of the departments of Cauca, Caldas, Quindío, Risaralda, and Valle del Cauca; T. cf. ecuadorensis (600–1,700 m) causes accidents to the east of the Central-Eastern cordillera in the departments of Cauca, Putumayo, and Nariño; T. fuhrmanni (1,400–1,800 m) causes accidents only in the department of Antioquia; and T. pachyurus (400–1,700 m), with a wide distribution in Colombia along the Magdalena River Valley, is responsible for severe cases of scorpionism in the departments of Antioquia, Caldas, Cauca, Cundinamarca, Huila, and Tolima (Guerrero-Vargas and Rodríguez 2011).
Izquierdo and Rodriguez (2012) reported a severe case of scorpion in a 12-year-old in the Magdalena Valley, caused by T. pachyurus: a matter of some minutes after being stung by the scorpion, the child was admitted to the local hospital in Tolemaida with emesis, progressing to hematemesis, sweating, mild respiratory distress, hypertension, and tachycardia. The patient was treated with sodium nitroprusside and prazosin. However, his blood pressure increased and he was referred to the Central Military Hospital in Bogotá. Thirty hours after the accident, the child was admitted to the pediatric intensive care unit with respiratory distress that progressed to respiratory failure and clinical signs of pulmonary edema. He suffered cardiac arrest and was revived and treated with five vials of antivenom imported from Mexico. He responded well to the treatment and after 10 days of hospitalization was discharged.
According to the Center for Information, Management, and Research in Toxicology (CIGITOX) of the Faculty of Medicine at the National University of Colombia, between 2006 and 2010, 1,783 cases of accidents with venomous animals were reported, of which 47 % related to cases of snake bite (a notifiable event in Colombia), 25 % involved scorpions, and spiders accounted for 11 %. The departments with the highest incidence of these accidents were Antioquia, Valle del Cauca, and Cundinamarca. It is important to note that in this same time period scorpionism was the second most prevalent accident after snake bite in Colombia, in addition to the reported five cases of child deaths caused by venom from the T. pachyurus scorpion (Rodríguez-Vargas 2012).
Diversity and Geographical Distribution of Scorpions of Medical Importance in Colombia
Colombia is a country with one of the richest biotic diversities of the planet, the greatest number of endemic species, and at the same time one of the most threatened, by different factors (Kattan et al. 2004). Evidence for this significant diversity is based on data on the number of species of plants and vertebrate animal groups. For other groups such as arthropods, the figures are still emerging due to a lack of information. Slowly, however, the knowledge gained of certain groups of insects and arachnids is beginning to assume greater importance.
A particular case is that of diversity of scorpions in Colombia, knowledge of which has doubled in the last two decades from 40 species (Flórez and Sánchez 1995) to 80 species (unpubl. data). These are grouped into 14 genera and five families, Buthidae being the most diverse of them. The family Buthidae contains the genera with the species that pose a risk to human health in Colombia: Centruroides and Tityus (Barona et al. 2004; Otero et al. 2004; Gómez et al. 2010), which are distributed in the dry forests of the Andean valleys of the Magdalena and Cauca rivers and in the Caribbean region. However, some species are seen as having more medical importance because of the frequency of accidents due to their synanthropic habits in densely populated areas, rather than the toxicity of their venoms.
Taxonomic Recognition of the Species of Medical Importance in Colombia
Genus Centruroides Marx, 1980
Centruroides margaritatus (Gervais, 1841)
Centruroides edwardsii (Gervais, 1843)
Genus Tityus C.L. Koch, 1836
Tityus asthenes Pocock, 1893
Tityus columbianus (Thorell, 1876)
Tityus forcipula (Gervais, 1843)
Tityus fuhrmanni (Kraepelin, 1914)
Tityus pachyurus (Pocock, 1897)
Tityus n. sp. aff. metuendus
Species of the Genus Centruroides
Species of the Genus Tityus
- Tityus (Atreus) asthenes (Fig. 7). It is a dark-brown species, with weak keels on the caudal segments, and exhibits a marked sexual dimorphism in the palps, these being longer and thinner in the males. T. asthenes is distributed along the Pacific coast of Colombia (Fig. 8), and human accidents are usually due to the fact that it is a species that often finds its way into the rural and tourist housing in the region.
- Tityus (Atreus) forcipula (Fig. 9). This is a dark-colored scorpion with reddish-brown palps and having keels formed by spiny granules over the caudal segments, with the granules behind each segment progressively increasing in size. It is one of the species with the widest distribution ranges in Colombia, located as it is in the mountainous regions of central and western Andean ranges in southwestern Colombia, taking in the departments of Caldas, Quindio, Risaralda, Cauca Valley, and Cauca (Fig. 8).
- Tityus (Atreus) fuhrmanni (Fig. 10). This species is limited to the department of Antioquia (northwest Colombia), in the city of Medellin and its surroundings (Fig. 8). It is dark in color and is characterized by a very strong spiny granule at the apical end of dorsolateral keels of caudal segments II to IV. Although the toxins of this species are not as powerful, the accidents are relatively common, as its habitat coincides with an area densely populated by man.
- Tityus (Atreus) pachyurus (Fig. 11). This species is related to T. forcipula, which differs by exhibiting a less granulation on the dorsal keels of the metasoma. It inhabits dry forests in the middle sector of the Magdalena River Valley (central Colombia), across the departments of Tolima, Cundinamarca, Boyacá, Antioquia, and Huila (Fig. 8). It is one of the species that has the most toxic poisons in Colombia and is the cause of one of the highest percentages of patient admissions in hospitals and health centers in the country. Notwithstanding, this species shares much in common with C. edwardsii, which also has significantly toxic venoms, the reason human populations in this region are more susceptible to envenomation by scorpions. Special care must be taken in the administration of antivenoms, since for this you ought to have previous evidence of the specimen that caused the accident.
- Tityus (Atreus) n. sp. aff. metuendus (Fig. 12). This species is related to T. forcipula and T. pachyurus, differing from them by exhibiting less granulation in the metasomal segments and having fewer pectinal teeth (16–20), while T. pachyurus and T. forcipula usually exhibit 19 or more pectinal teeth. It inhabits southern Colombia in the urban area of the city of Popayan (Cauca) (Fig. 8) where it causes frequent accidents in the human population.
Taxonomic Key to the Species of Scorpions of Medical Importance in Colombia
Inner edge of the fingers of the chela has eight to nine oblique rows of denticles; yellowish-brown colorations – g. Centruroides…2.
Inner edge of the fingers of the chela has 16–18 oblique rows of denticles; dark-brown coloration – g. Tityus…3.
Pedipalps have abundant pilosity; dorso-marginal keel on the hand of the chela shows profuse pilosity – C. edwardsii.
Pedipalps have little pilosity; dorso-marginal keel on the hand of the chela shows no pilosity – C. margaritatus.
Small-sized species (under 45 mm), bodies with gray-brown colorations and with scattered white markings, with a rhomboid thorn under the stinger – T. columbianus.
Large-sized species (over than 60 mm), bodies with dark or reddish-brown colorations, with acute thorn under the stinger…4.
Dark-brown coloration (including the pedipalps); males with pedipalps longer and thinner than those of females – T. asthenes.
Dark coloration, with reddish-brown pedipalps; palps of the males similar to those of the females…5.
Caudal segments with lateral dorsal keels provided with conspicuous spiny granules…6.
Caudal segments with lateral dorsal keels provided with moderated spiny granules…7.
Dorsolateral keel granules gradually increasing in size toward the rear end – T. forcipula.
Dorsolateral keel granules increasing in size toward the rear end, with the last granule much higher than those of the rest – T. fuhrmanni.
Pectines provided with 19–24 denticles – T. pachyurus.
Pectines provided with 16–20 denticles – T. n. sp. aff. metuendus.
Works About the Toxinology of Scorpion Venom in Colombia
Toxinological Characterizations of Some Venoms of Scorpions with a Geographical Distribution in Colombia
Centruroides margaritatus Venom
The venom of the C. margaritatus scorpion from the department of Cauca in southwestern Colombia was investigated. This venom has an LD50 in mice of 42.83 mg/kg and causes the following symptoms: excitability, salivation, piloerection, and dyspnea. The whole venom sample was fractionated in a size exclusion column, where 9 fractions were obtained. The most abundant fractions – II, III, IV, and V – were inoculated into a preparation of amphibian gastrocnemius muscle, yielding the result that fractions II, IV, and V inhibit muscle contraction (Guerrero-Vargas et al. 2007).
Dueñas-Cuellar et al. (2009) evaluated the cytotoxic and genotoxic effects of C. margaritatus venom on mice, using the micronucleus (Mn) assay, and the rate of polychromatic erythrocytes (PCE)/1000 cells/animal was counted; the mice were treated by intraperitoneal administration with saline solution (0.9 %) as negative control and three experimental venom doses (9.32, 18.65, and 37.31 mg/kg) and cyclophosphamide (50 mg/kg) as positive control. The cytotoxic effect expressed in PCE, decreased directly related with the time of treatment and genotoxic effect, was only evidenced in the higher dose at 40 h after treatment.
In 2010, in an undergraduate thesis on venom of the scorpion C. margaritatus, injecting three groups of juvenile rats at sublethal doses, a cardiotoxic effect was triggered, characterized by tachycardia and electrocardiographic changes. Between 30 and 40 min after the inoculation of the venom, the rats of the three experimental groups registered a higher number of irregular heart rhythms, frequently occurring in the groups treated with the highest concentration of venom. In the experimental groups, records were found with irregular RR distances and replicated F waves pertaining to atrial fibrillation, whose frequency of occurrence was higher in the groups exposed to higher doses. ECG records were found with wide and deformed QRS complexes, irregular with changes in their morphology characteristic of a polymorphic ventricular tachycardia. In addition, the experimental groups revealed the presence of wide, deformed, and polymorph QRS complexes called ventricular systoles or premature ventricular complexes (PVC) (Arenas 2010).
Tityus fuhrmanni Venom
The earliest known work in the line of toxinological characterization dates from 2002, with the venom of the T. fuhrmanni scorpion endemic to the department of Antioquia, in northwestern Colombia. This venom has an LD50 determined on mice corresponding to 3.9 mg/kg, and the symptoms of envenomation that it causes, also in mice, are salivation, piloerection, diaphoresis, somnolence, and systemic complications such as tachypnea, ataxia, and seizures (Gómez et al. 2002).
Tityus pachyurus Venom
Barona et al. (2004) investigated the venom of the T. pachyurus scorpion from the Magdalena River Valley in central Colombia. Symptoms of envenomation presented by mice were sialorrhea, dyspnea, diaphoresis, ataxia, behavioral changes, and hyperglycemia. The LD50 was determined to be 4.8 mg/kg. The neutralizing capacity for this poison by three antivenoms imported from Brazil, Mexico, and Venezuela was also determined.In an experimental study undertaken as a toxicology master’s thesis, whose objective was to evaluate the effects of scorpion venom inoculation on target organs, a variety of statistically significant abnormalities were observed in the histopathological analysis of the different organs of mice exposed to varying doses (0 %, 25 %, 50 %, and 75 % of LD50) of T. pachyurus venom, showing dependence between the dose of poison administered intraperitoneally and the severity of disorders such as pulmonary, hepatic, splenic, and renal congestion, hepatic vacuolar degeneration, and pulmonary alveolar hemorrhage (p < 0.05). Other conditions (e.g., cardiac, suprarenal, and pancreatic congestion, pulmonary edema, and pulmonary microthrombosis) pointed to a lesser degree of dependence regarding the severity of the damage with respect to the exposure dose (p < 0.1). It should be noted that in two of the specimens exposed to 75 % of LD50, it was possible to observe the presence of localized necrosis of the hepatocytes (Rodríguez 2008). Figure 14 indicated the histological alterations in the lung, liver, spleen, and kidney.
In a technical report on research conducted by Beltrán et al. (2011), the cardiotoxic effect was evaluated by recording the electrocardiographic and histopathological changes induced by the pool venom of T. pachyurus, 3 h following envenomation in rats inoculated with sublethal doses. Electrocardiographic records were obtained that were characterized by unusual rhythms, with a delay in the activation of the right ventricle, showing typical QRS morphology in V1 rSR’, indicating the presence of incomplete right bundle branch blockage (RBBB), voltage variations, and elevation of the T wave. The levels of plasma cardiac enzyme CK and isoenzyme CK-MB increased significantly and are directly proportional to the amount of venom injected. In the histopathological analysis of the hearts of rats treated with 20 %, 40 %, and 80 % of the LD50, interfibrillar edema of the heart muscle was identified, with a severity proportional to the inoculated dose. Additionally, in the group of animals inoculated with 80 % of the LD50, alterations were observed such as cytoplasmic vacuolation, hypertrophy of myocytes, and moderate congestion of the ventricles.
Tityus n. sp. aff. metuendus Venom
Also in the 2010, the preliminary toxinological characterization of the venom from the scorpion T. n. sp. aff. metuendus was performed. In this work, the biological activity of venom on the muscular contraction (MC) of the frog Rhinella marina and the antimicrobial activity on three pathogenic bacteria (Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus) and three pathogenic fungi (Candida albicans, Candida krusei, and Cryptococcus neoformans) were researched. The venom of the T. n. sp. aff. metuendus scorpion showed a strong effect on MC and on the contraction time (CT); this effect is dose dependent and the major alteration of the MC was observed in the dose equivalent at 50 % (0.288 mg/kg). Regarding the antimicrobial activity, the venom in all the concentrations inhibited the growth of P. aeruginosa, and the most effective dose was given at 1 mg/ml; the growth of S. aureus was also inhibited in all concentrations being the most effective at 0.5 mg/ml; in the case of C. albicans, the growth was inhibited in the venom concentrations of 0.016–1 mg/ml showing a better effect at 1 mg/ml; the C. krusei growth was inhibited by venom concentrations of 0.016–1 mg/ml and that of 1 mg/ml showed the major effect. However, for E. coli and C. neoformans, the concentrations of the venom did not have a significant effect (Morales-Duque et al. 2010).
Identification and Characterization of Toxins from Various Venoms from Scorpions with a Geographical Distribution in Colombia
As regards the venom of T. pachyurus, Barona et al. (2006), using HPLC and mass spectrometry, reported that this venom comprises at least 104 components with different molecular masses. They further chemically characterized and determined the biological activity of two new toxins: Tpa1 (a potassium channel blocker), containing 32 amino acid residues and a molecular weight of 2,900 Da, and Tpa2, of molecular weight 7,522.5 Da and 60 amino acid residues, toxic in mammals and classified as a β-sodium scorpion toxin (βNaScTx).
In a comparative study seeking to identify new putative sodium scorpiotoxins from T. pachyurus collected in Colombia and T. obscurus in Brazil, Guerrero-Vargas et al. (2012) reported, following construction of a cDNA library of venom glands, five new putative Na+ toxins for T. pachyurus, called Tpa4, Tpa5, Tpa6, Tpa7, and Tpa8 and 15 for T. obscurus. Tpa8 is the first toxin identified and classified as β-excitatory anti-insect in scorpion of the new world. Toxins Tpa4, Tpa5, and Tpa6 presented a high percentage of identity with toxins classified as αNaScTx, and putative toxins Tpa7 and Tpa8 are sequences related more to βNaScTx. These authors also constructed a phylogenetic tree using the NaScTx they had identified and NaScTx from scorpions of the genus Tityus deposited in different databases. This phylogenetic analysis indicated a marked geographical separation between the scorpions of the genus Tityus living north of the Amazon River and those distributed to the south of this basin.
In another work concerned with venom of the scorpion C. margaritatus, Guerrero-Vargas et al. (2009), also using HPLC and MS, reported 91 components of different molecular weights. Here, 54 % of the molecular weights were between 2.5 and 6.0 kDa, where toxins that affect the channels K are usually found; 13 % of the molecular weights were in the range of 6.5–8.0 kDa, the range in which toxins that modulate voltage-dependent Na channels can be found; and 33 % of the molecular weights were small compounds of 2.0 kDa. Two new toxins were also isolated and characterized biochemically: MgTx2 with 24 amino acid residues, three disulfide bridges, and molecular weight 2.6 kDa that displayed a high similarity to toxins classified as alpha-KTx, and MgTx3, containing 30 amino acid residues, three disulfide bridges, and 3.38 kDa molecular weight that showed no similarity to any other toxins present previously described.
Pathophysiology of Scorpion Accidents in Colombia
When a scorpion sting occurs, the venom is primarily inoculated into the subcutaneous space, moving quickly to the central circulation where it is distributed by tissues and such organs as the kidneys, muscles, intestines, liver, lungs, and heart (D’Suze et al. 2004). This poison, when inoculated in mammals – in our case humans – acts primarily at specific locations of the sodium channels of excitable and non-excitable cells, causing a depolarization of the nerve endings, triggering the release of acetylcholine, epinephrine, and norepinephrine. These abnormally released neurotransmitters are responsible for the majority of the clinical symptoms observed in the course of the scorpionism (Chippaux and Goyffon 2008; D’Suze et al. 2011).
The poisons of scorpion species present in Colombia, especially those of the genus Tityus , have a DL50 close to those obtained for other scorpions of importance in Latin America and are lower than those calculated for other species of importance such as Tityus discrepans, the most clinically important species in Venezuela, a country that reports an average of 800 accidents/year (Teixeira et al. 2001). Nevertheless, in Colombia no official data exist on the impact of this envenomation on morbidity and mortality in our country.
The systemic clinical abnormalities associated with scorpion envenomation have been observed in experimental studies, reports and case series, and observational studies (Gómez et al. 2002, 2010; Pineda 2002; Barona et al. 2004; Otero et al. 2004) and are related to processes of neurotoxicity, characterized by hyperactivity and intense and persistent depolarization of the autonomic fibers with the consequent massive release of neurotransmitters (Gwee et al. 2002). These elements have been described previously for other species of scorpion of medical importance worldwide, such as Leiurus quinquestriatus, Androctonus australis, T. serrulatus, T. discrepans, and Centruroides exilicauda, among others (Rodríguez 2008).
The findings reported by Rodríguez (2008) are consistent with the exposure of the different individuals to venom with a low histotoxic and necrotizing power, which produces mainly neurohormonal changes that lead to the onset of hemodynamic disturbances such as increased mean arterial pressure and pulmonary arterial pressure, decreased cardiac output, and progressive increase in myocardial oxygen consumption, and are compatible with the clinical presentation of commitment diastolic compromise, left ventricular dysfunction, cardiovascular collapse, and increased frequency of sudden death associated with ventricular arrhythmias observed in case reports and described in other genera and species of the family Buthidae (Murthy 2000; Gómez et al. 2010).
In addition several alterations associated with the presentation of lung injury and how congestion, edema, and alveolar hemorrhage are viewed in the histopathological analysis that are important components of the acute respiratory distress syndrome observed in case reports have been reported (Yugandhar et al. 1999; Murthy 2000; Rodríguez 2008; Izquierdo and Rodríguez 2012).
Other events such as the activation of the renin-angiotensin-aldosterone system by stimulation of the sympathetic system may be related to the reduction of effective blood flow due to the passage of intravascular fluid into the interstitium driving the emergence of peripheral circulatory failure that can be seen in the experimental and clinical descriptions of congestion of organs such as the lung, liver, spleen, and kidney (Yugandhar et al. 1999; Rodríguez 2008; Izquierdo and Rodríguez 2012).
Finally, it is possible to find deterioration of liver function, brought on by the processes of congestion and hypoxia, secondary to cardiocirculatory and respiratory dysfunction, which together with other processes such as the increase in the flow of intracellular Ca2+ contribute to the presentation of events such as vacuolar degeneration. The combination of all these circumstances may also contribute to the establishment of cellular anaerobic metabolism leading to multiple organ damage (Rodríguez 2008).
All these changes are clinically compatible with the onset of multisystem organ dysfunction syndrome, in which changes such as increased respiratory rate and dyspnea can be seen, encountered within the clinical framework, and observed within the clinical framework of a variety of victims of moderate and severe envenomations with T. pachyurus, T. asthenes, and T. furhmanni that may be accompanied by other neurological disorders such as hypoactivity, drowsiness, spastic movements, twitches, muscle weakness, lacrimation, salivation, priapism, and even ejaculation and central neurological disorders such as ataxia, motor incoordination, as well as convulsions (Gómez et al. 2002, 2010; Otero et al. 2004; Izquierdo and Rodríguez 2012).
Clinical Characteristics of the Scorpion Accident in Colombia
Scorpion accidents often occur in the evening or at night, and their occurrence has been associated in some descriptions – such as that carried out on the hillsides of El Volador in Medellin (Antioquia) – with the discovery of these animals in areas of clutter featuring items of everyday use in different places inside and outside the home such as on floors, among utensils, in clothes, in shoes, on walls, or in gardens under logs or leaf litter (Gómez et al. 2002).
Regarding the frequency of accidents according to the body area affected, there was a preponderance of stings on the feet and lower limbs, followed by thr upper limbs, abdomen, thorax, and head (Gómez et al. 2002, 2010; Barona et al. 2004; Otero et al. 2004). This type of accidents occurs most frequently in the productive ages (between 15 and 45 years), followed by accidents in children under 15 years, in whom a higher morbidity and mortality are a characteristic, especially in children under 6 years (Otero et al. 2004).
Among systemic clinical changes observed in case series and observational and experimental studies, tachycardia, vomiting, diaphoresis, abdominal pain, tachypnea, salivation and dysphagia, cyanosis, dehydration, hypertension, and bradycardia can be mentioned (Gómez et al. 2002, 2010; Rodríguez 2008). Clinical frameworks accompanied by hyperglycemia, urinary retention, hyperkalemia, hyperamylasemia, hypocalcemia, and hyponatremia have also been described (Gómez et al. 2002; Izquierdo and Rodríguez 2012).
In an effort to understand and classify better scorpionism at the global level, in January 2007, a group of 16 experts from four continents (America, Africa, Asia, and Europe) was formed. More details of their work methods and results obtained can be consulted in the work of Khattabi et al. (2011). This meeting of experts proposed classifying scorpionism in three categories: class I shows only local manifestations, class II are generally lesser systemic manifestations that do not put life at risk, and class III correspond to systemic manifestations that suggest risk to the life of the patient.
Clinical classification of the scorpionism accident for Colombia
Mild systemic manifestations
Moderate systemic manifestations
Severe systemic manifestations
Local ecchymosis (variable)
Isolated emesis Rhinorrhea
Shortness of breath
Gastrointestinal bleeding pancreatitis
Neurological compromise (coma)
Bullous rash (rare)
Degree of toxicity of venom injected.
Species and size: the genera Centruroides and Tityus are most often related to the occurrence of systemic effects and even death. In some cases, the size of the scorpion causing the sting is related to a greater amount of venom injected and therefore to the effects produced in the victim (Barona et al. 2004).
Time between accident and access to hospital care. A stronger possibility of deleterious effects was found to be associated with an increase in the delay in obtaining assistance (Pineda 2002; Otero et al. 2004).
Onset of symptoms such as vomiting. It appears that the onset of vomiting and its intensity in the first 2 h can point to the gravity of the envenomation (Otero et al. 2004).
Lethality of poison: there are differences between the potency and lethality of different scorpion venoms even within the same genus, according to the LD50 reports available, among which are T. fuhrmanni (3.9 μg/g) (Gómez et al. 2002), T. asthenes (6.1 μg/g mouse) (Gómez et al. 2010), T. pachyurus (4.8 μg/g in 2004 and 6.5 μg/g in 2008) (Barona et al. 2004; Rodríguez 2008), and C. margaritatus (42.83 μg/g) (Guerrero-Vargas et al. 2007).
In one case report by Izquierdo and Rodríguez (2012) relating to a presentation of severe scorpionism, cardiovascular compromise and cardiac arrest, secondary to pulseless ventricular tachycardia, were observed in a patient of 12 years old in the town of Tolemaida, 2 h from Bogota. In this case, it was possible to observe the presence of an intense stimulant effect on the sympathetic nervous system with cardiovascular impact expressed in ventricular relaxation disorder, ischemic compromise, and secondary ventricular dysfunction which predominated in the echocardiographic controls following the accident.
Suggested Medical Treatment
The management of scorpion accidents is generally oriented toward stabilizing the victim and controlling the symptoms of the envenomation while neutralizing the poison; it is important to note that moderate accidents require the continuous monitoring of the patient and severe accidents require hospitalization at the third level of complexity where the patient can be treated in intensive care. Measures used most often as part of the general support of the patient with scorpion envenomation include the following. Is necessary to mention that the patient showed a marked reduction in the values of ionized calcium during their stay in the intensive care unit.
Treatment of pain: in common with the rest of the countries around the world, the emphasis in Colombia has been on pain management with the use of nonsteroidal anti-inflammatory drugs (NSAIDs) and the use of local anesthetics and non-opioid analgesics (Pineda 2002; Otero et al. 2004). Regarding corticosteroids on the other hand, since there is no conclusive clinical evidence that either supports or restricts their use, this intervention has not been included in the recommendations for the clinical care of patients.
Hemodynamic support: this is required in cases in which the patient may present with changes suggestive of distributive shock resistant to hydration management, or heart failure, and includes the treatment of the hypertensive crisis, in which a number of alternatives have been used that include the α1 blockers such as prazosin to control the hypertensive crises and the use of inotropes such as dopamine, increase: and calcium gluconate in the treatment of myocardial dysfunction, increase: and hypocalcemia if it occurs (Pineda 2002; Izquierdo and Rodríguez 2012).
Ventilatory support: used in severe cases of neurological compromise, status epilepticus (SE) with respiratory compromise, or presentation of pulmonary edema (Pineda 2002).
Maintenance of normoglycemia: because in Colombia there are very few case reports of scorpion accidents occurring with critical elevations of blood glucose levels, treatment has been directed mainly to the maintenance of normal levels with measures such as the administration of isotonic fluids and continuous monitoring (Otero et al. 2004; Izquierdo and Rodríguez 2012).
Use of Antivenoms
It is important to note that treatment of scorpion accident globally has been the subject of a range of controversies and their effectiveness can vary from report to report.
In Colombia, it has not been possible to establish clearly the conditions under which specific serum therapy ought to be used, and there is no domestic production of antivenom. However, currently, the use is being made of specific fabotherapeutic antivenom imported from Mexico.
Although this antivenom is produced from scorpion species of the genus Centruroides present in Mexico, some authors reported cross-reactivity for venoms of scorpions of other genera, and in experimental testing evidence, a reduction was observed on the lethal effect of T. pachyurus venom in mice (Otero et al. 2004; Izquierdo and Rodríguez 2012).
Recommended use of antivenoms (Adapted from Ayerbe and Rodríguez 2008)
Severity of scorpionism
Observation for 6 h
Observation for 12 h
Two vials intravenously, observation for 12 h
Four vials intravenously, 24 h minimum observation
Among the major complications, we find the onset of hypertensive emergency, heart failure, and cardiac arrest by malignant ventricular arrhythmias (Izquierdo and Rodríguez 2012), acute pulmonary edema and respiratory distress syndrome in adults (Izquierdo and Rodríguez 2012), acute pancreatitis (describe in a case of a child stung by T. asthenes) (Otero et al. 2004), bowel bleeding (Gómez et al. 2010), and kidney failure (Rodríguez 2008; Izquierdo and Rodríguez 2012).
In some areas of the country (e.g., in the municipality of El Patia, Cauca Department), the development of diabetes mellitus has been observed in Black individuals with no family history or other risk factors, in whom only a previous event of an scorpion accident serves as a nexus. However, studies are needed to corroborate these observations.
Finally, it is important to increase interdisciplinary efforts in Colombia that establish mandatory surveillance of all accidents by venomous animals, including scorpion accidents, in order to establish their actual impact on the health of the Colombian population, develop prevention strategies and appropriate treatment, and form networks of information and cooperation to facilitate access to the antivenoms in cases that warrant it.
Conclusion and Future Directions
The study of venomous animals and their venoms is a complex theme that ideally should be carried out within the field of toxinology, a transdisciplinary science.
Toxinology sciences are in the early stages of development in Colombia and require serious investment by the state organizations for science and technology in order to advance to a respectable world positioning.
Looking beyond the fine efforts of Khattabi et al. (2011) to unify the indications and symptoms of scorpionism, a new global consensus is still lacking. For this reason, a system of classification of scorpionism for Colombia is proposed here, comprising four different degrees – local manifestations, mild systemic manifestations, moderate systemic manifestations, and severe systemic manifestations.
Severe scorpionism in Colombia is caused not only by T. pachyurus, as has been reported (Chippaux and Goyffon 2008). Following exhaustive review, it was shown that severe scorpionism is caused by seven species: two from the genus Centruroides (C. edwardsii and C. margaritatus) and five from the genus Tityus (T. asthenes, T. forcipula, T. fuhrmanni, T. pachyurus, and T. n. sp. aff. metuendus).
The species T. columbianus does not cause severe scorpionism. Events recorded are rather of moderate scorpionism but with a high incidence, principally in Bogota D.C. As such, it is ranked as a dangerous species.
Scorpionism and species scorpions have an important, wide altitudinal and latitudinal distribution in Colombia – from 0 to 2,800 masl and all cardinal points, respectively.
Colombia currently has to import its scorpion antivenom from Brazil and México. It is recommended that government health authorities promote the manufacture of polyvalent antivenom, produced from pools of venoms of the country’s most dangerous scorpions.
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