There are 2433 known scorpion species worldwide. The occurrence of envenomation is uncommon from venomous species, with over 1 million envenomations per year, and the World Health Organization have classified scorpion envenomations as a neglected health problem1.
There are approximately 160 recorded species in the Brazilian territory, where Tityus serrulatus, T. stigmurus, T. bahiensis, and T. obscurus are associated with higher clinical importance2,3. T. serrulatus is associated with envenomations in the South, Southeast, Midwest, and Northeast regions. This species is absent in the northern region2, where envenomation by T. obscurus, T. metuendes, and T. silvestris prevails4,5.
T. serrulatus is ranked among the 30 most dangerous scorpion species in the world and is of utmost clinical importance in South America. This species is 55-65 cm in length, is dark or light yellow in color, and is known to have three and five spinoid granules on its III and IV metasomas. Its telson has an elliptic vesicle where the aculeus and a prominent subaculear tubercle can be found6.
This article describes the first case of envenomation by T. serrulatus, a species non-native to the northern region of the Brazilian Amazon and more specifically in the city of Belém, in the Pará State.
A 27-year-old male sales person was stung by a scorpion on the left gluteal region at 2 a.m. on 5th February 2019. This occurred while the patient was unloading bunches of bananas transported from Bahia by truck at the Supply Centre of Belém, Pará – CEASA/PA (coordinates: 01º 27′ 21″ S, 48º 30′ 16″ W) (Figure 1). The patient presented with moderate pain, erythema, and light edema at the sting site. He was referred to clinical care at HPSM Mário Pinotti three hours after the envenomation, bringing the specimen with him for identification. Two ampoules of anti-arachnid serum were administered, and the Belém Toxicological Information Centre was contacted for guidance and species identification. The incident was classified as low-risk; the patient was managed with symptomatic treatment, life support, and active observation for 6 hours. He was discharged after clinical improvement and the scorpion was identified as T. serrulatus (Figure 2).
The ethics committee at the University Hospital João de Barros Barreto, Belém, PA approved this case study under certificate number 09257319.5.0000.0017. The scorpion was given to the care of the Laboratory of Entomology and Venomous Animals, which is a part of the Nucleus of Tropical Medicine at the Federal University of Pará (UFPA).
The Tityus genus is associated with most cases of scorpionism in Brazil. Cases are primarily associated with the species T. serrulatus and T. bahiensis in the East, South, and Midwest regions7. T. stigmurus and T. obscurus are the major causes of stinging incidents in the Northeast and North regions, respectively4,8.
Four scorpion families, 12 genera, and 44 species are commonly found in the North region, but T. serrulatus is not among them6. T. serrulatus has parthenogenetic reproduction2, which is the ability to reproduce without fertilization and without a co-parent. This implies that a single specimen transported to a new location could reproduce and develop a colony. Road networks, which are the main logistics route in Brazil, are presumably enabling the spread of this species. Lourenço and Eicksteadt9 described the species in the state of Rondônia but did not associate it with any clinical cases. This article describes a scorpion-related envenomation caused by a specimen that was carried in fruit cargo. Torres et al.10 reported a similar case where a fruit distributor was stung by T. serrulatus while handling green peppers that originated in the state of São Paulo.
Pain after a scorpion sting is quite common, and is a hallmark of almost all cases4,7,8. Findings of localized pain, edema, and erythema at the sting site classify the envenomation as low-risk11. Common anatomical sites associated with scorpionism are the hands and feet3. T. serrulatus is the species most associated with high-risk envenomations and lethal cases in Brazil7. According to Silva et al.12, the low-risk envenomation described here may be due to a regional variation of this species found in the state of Bahia, which is known to have less toxins than other T. serrulatus species.
Antitoxin treatment is based on the risk stratification of the envenomation. It is administered in moderate and high-risk cases, while symptomatic medication and clinical observation are advised in low-risk cases11. This advice was provided to the healthcare team by the Toxicological Information Centre, but the victim had already received the antitoxin dose in the emergency department. This behavior shows the need for increased training of health professionals, so that envenomations caused by venomous animals can be handled according to standardized protocols. It also highlights the importance of toxicological information centers in guiding treatment of such cases.
This is the first described case of scorpionism caused by T. serrulatus as described by Lutz & Mello, 1922 (Scorpiones, Buthidae). It is a species non-native to the state of Pará (North region), Amazonian region. The species originated in the state of Bahia (Northeast) and was transported by truck (amongst fruit) and was responsible for a low-risk scorpionism incident. If the species were to be introduced in the northern region, it could cause ecological disruption and may pose a threat to the local homeostasis and public health. Hence, close surveillance of invading species of the Amazonian Scorpio fauna is important, as is the need for public health projects to improve the management of envenomation and prevent future accidents.