Toxicon 189 (2021) 1–6 Contents lists available at ScienceDirect Toxicon journal homepage: http://www.elsevier.com/locate/toxicon Case report Envenomation by opisthoglyphous snake Thamnodynastes hypoconia (Cope, 1860) (Dipsadinae: Tachymenini) in southern Brazil Marluci Müller Rebelato a,*, Vinícius Yuri Kingeski Ferri a, Diego Anderson Dalmolin b, Alexandro Marques Tozetti c, Laura Verrastro d a Programa de Pos-graduaç´ ao~ em Biologia Animal, Laboratorio´ de Herpetologia, Departamento de Zoologia, Instituto de Bioci^encias, Universidade Federal do Rio Grande do Sul, Avenida Bento Gonçalves 9500, Agronomia, 91501-970, Porto Alegre, RS, Brazil b Programa de Pos-graduaç´ ao~ em Biologia Animal, Laboratorio´ de Evoluçao,~ Sistematica´ e Ecologia de Aves e Mamíferos, Departamento de Zoologia, Instituto de Bioci^encias, Universidade Federal do Rio Grande do Sul, Avenida Bento Gonçalves 9500, Agronomia, 91501-970, Porto Alegre, RS, Brazil c Laboratorio´ de Ecologia de Vertebrados Terrestres, Universidade do Vale do Rio dos Sinos, Avenida Unisinos 950, 93022-000, Sao~ Leopoldo, RS, Brazil d Laboratorio´ de Herpetologia, Departamento de Zoologia, Instituto de Bioci^encias, Universidade Federal do Rio Grande do Sul, Avenida Bento Gonçalves 9500, Agronomia, 91501-970, Porto Alegre, RS, Brazil ARTICLE INFO ABSTRACT Keywords: We report here a case of human envenoming by Thamnodynastes hypoconia, a common and abundant non-front- Colubroid snakes fanged snake belonging to the subfamily Dipsadinae. The case was registered in the municipality of Tapes, Rio Non-front-fanged Grande do Sul state, Brazil, in a 27-year-old female. The snakebite was on the wrist of the left arm while handling Non-venomous snake the snake in a field outing. No pain sensation was noted during the bite, and after 20 minutes edema developed Snakebite along the hand and forearm with a slight sensation of numbness and mild pain when moving the fingers.After 15 Thamnodynastes hours, the victim began to develop erythema, paraesthesia, and a sensation of warmth at the bite site. After 30 hours, ecchymosis occurred on the fingers and forearms, and the edema began to decrease. After 70 hours from the time of the bite, ecchymosis along with pruritus and mild pain were still evident. The patient was treated with prescribed medications, and after 7 days no further symptoms were observed. This is the first reported case of envenoming by T. hypoconia. 1. Introduction has aglyphous or opisthoglyphous dentition and are considered harm­ less due to their inefficientvenom injection in humans (Gans and Elliott, The annual number of people bitten by snakes in Brazil can reach 1968; Weinstein and Kardong, 1994). However, Dipsadinae, called close to 30,000. In 2017, out of a total 28,000 cases, 23,000 (~81%) “non-venomous”, have the Duvernoy’s gland which is a homologous were caused by venomous snakes (Viperidae and Elapidae; front-fanged structure to the venom gland of viperids and elapids (Jackson et al., snakes, FFS), 1890 (~7%) by non-venomous snakes and 3245 by un­ 2017). The Duvernoy’s gland produces toxins used to subdue prey identified snakes (~12%) (SINAN, 2019). However, the number of ac­ (Kardong, 2002), but very little is known about these toxins and their cidents with non-venomous and non-front-fanged snakes (NFFS) snakes actions on living tissues (Ching et al, 2006, 2012; Fry et al., 2003; Pei­ in Brazil is likely underestimated since many bite victims do not seek choto et al, 2011, 2012). In general, the symptoms of accidents caused medical attention in a healthcare center, and as such are unreported. In by these non-venomous snakes are local pain, edema, and ecchymosis Brazil, accidents with non-venomous snakes are caused mainly by spe­ (Prado-Franceschi and Hyslop, 2002). cies of the family Colubridae and subfamilies Colubrinae and Dipsadi­ In Brazil, most accidents with Dipsadinae species occur with the nae, which are rear-fanged snakes (RFS) orNFFS (Junqueira-de-Azevedo genera Clelia, Erythrolamprus (former Liophis), Helicops, Philodryas, et al., 2016; Salomao~ et al., 2003; Weinstein et al., 2011). Oxyrhopus, Sibynomorphus, Thamnodynastes and Xenodon (former Unlike snakes of the Viperidae and Elapidae families, which have Lystrophis) (Araújo et al., 2018; Barbosa et al., 2020; Prado-Franceschi solenoglyphous and proteroglyphous dentition, respectively, Dipsadinae and Hyslop, 2002; Quintela, 2010; Salomao~ et al., 2003; Silveira and * Corresponding author. E-mail addresses: [email protected], [email protected] (M.M. Rebelato), [email protected] (V.Y.K. Ferri), [email protected] (D.A. Dalmolin), [email protected] (A.M. Tozetti), [email protected] (L. Verrastro). https://doi.org/10.1016/j.toxicon.2020.10.022 Received 22 June 2020; Received in revised form 19 October 2020; Accepted 27 October 2020 Available online 2 November 2020 0041-0101/© 2020 Elsevier Ltd. All rights reserved. M.M. Rebelato et al. Toxicon 189 (2021) 1–6 Nishioka, 1992). Thamnodynastes spp. are neotropical in nature and It is important to highlight that based on the general aspects of the belong to the Tachymenini tribe (Zaher et al., 2009). Thamnodynastes hand and general symptoms, the medical team believed that it was a hypoconia (Cope, 1860) (Fig. 1) occurs in the northeast, midwest, venomous snakebite from the Bothrops genus. They recommended that southeast, and south of Brazil, Paraguay, Uruguay, and Argentina the victim be transferred to another hospital at Porto Alegre city (the (Franco, 1999; Giraudo, 2001). It is a small opisthoglyphous snake, state capital) situated 130 km from the medical center where the bite reaching approximately 70 cm in total length and displays a very was initially evaluated. The professionals reported that Porto Alegre was aggressive behavior when threatened (Giraudo, 2001). It is a viviparous, the closest urban center with the availability of antivenom for Bothrops nocturnal species, which feeds primarily on frogs (Bellini et al, 2013, bite. The victim, a professional herpetologist, declared that the snake 2014; Rebelato et al., 2016, 2020). We report a case of symptoms was not a Bothrops but Thamnodynastes hypoconia. The hospital team following the bite to a researcher during manipulation of the snake contacted the Toxicological Information Center of Rio Grande do Sul T. hypoconia in the field in southern Brazil. (Centro de Informaçao~ Toxicologica´ - CIT), and mentioned the species involved in the accident. The CIT, which advises and guides the occur­ 2. Case report rence of toxic accidents in the state, confirmed that bites from T. hypoconia had no known medical risk and the patient could leave the On Feb 15th, 2016, a 27-year-old female, 68 kg body weight, 183 cm hospital. Before being discharged, the patient had the bite site cleaned tall, was bitten while handling a T. hypoconia (32.4 cm snout-vent with iodine and covered with a bandage (Fig. 3E). Paracetamol 500 mg length; 11 cm tail length and 10.30 g body weight) to take body mea­ and Ibuprofen 400 mg were also prescribed as analgesic and anti- surements when the snake attached its jaws to the left hand wrist inflammatory every 6 h, but the patient used only Ibuprofen. (Fig. 3A). The accident happened around 8:45 p.m. during a fieldouting On the second day, 15 hours after the accident, the hand and forearm in a wetland area on the shore of the Patos Lagoon, in the municipality of showed edema, erythema, paraesthesia, and a sense of warmth at the Tapes, Rio Grande do Sul state, Brazil (Fig. 2). bite site with mild pain (Fig. 4A). After 20 hours, body temperature ◦ The snake held its bite for approximately 60 seconds before being (37.4 C), blood pressure (130/80 mm), and heart rate (97 bpm) were manually removed, forcing the opening of the mandible by raising the measured again. On the third day, after 30 hours, all fingers and inner maxilla. The bite caused minimal immediate pain due to perforation by part of the forearm presented ecchymosis and moderate pain when the snake’s teeth, and after the snake is removed from the left wrist, two performing any muscular effort (Fig. 4B and C), however, the edema perforations were observed due to puncture by the opisthoglyphus began to decrease. On the fourth day, 70 hours after the bite, the hand dentition with slight bleeding surrounded by mild local edema (Fig. 3B). and forearm no longer showed edema and the ecchymosis changed from After 20 minutes, the edema spread over the hand and forearm, with a a purple color to a yellowish-green color, followed by pruritus, mild slight sensation of numbness and pain during fingermovement (Fig. 3C). pain, and itching (Fig. 4D and E). On the fifth day, the yellowish-green Three hours after the incident, the left hand was quite swollen in relation color was practically imperceptible and there was no more pain when to the right hand (Fig. 3D). performing any physical effort. Finally, on the seventh day no symptoms Following 4 hours of the accident, the victim was taken to the Basic were visible. It is important to remember that these symptoms happened Health Unit at Arambar´e city. The following vital signs were recorded: in a healthy woman who had no medical history of allergies, chronic or ◦ body temperature: 36.7 C, blood pressure: 110/60 mm, and heart rate: autoimmune diseases, nor use of any prescribed or other medications. 85 bpm. The medication Celestamine® (dexchlorpheniramine maleate - The victim had a history of prior bites by T. hypoconia during field ac­ 2 mg + betamethasone - 0.25 mg) was prescribed, with posology of one tivities without symptoms observed. However, this was the firsttime the tablet every 8 hours for 5 days. During the attendance, the health pro­ snake bit and held on for longer, managing to insert the opisthoglyph fessional requested the patient go to Nossa Senhora Aperecida Hospital fangs.