Impact of Scyphozoan Venoms on Human Health and Current First Aid Options for Stings
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toxins Review Impact of Scyphozoan Venoms on Human Health and Current First Aid Options for Stings Alessia Remigante 1,2, Roberta Costa 1, Rossana Morabito 2 ID , Giuseppa La Spada 2, Angela Marino 2 ID and Silvia Dossena 1,* ID 1 Institute of Pharmacology and Toxicology, Paracelsus Medical University, Strubergasse 21, A-5020 Salzburg, Austria; [email protected] (A.R.); [email protected] (R.C.) 2 Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Viale F. Stagno D'Alcontres 31, I-98166 Messina, Italy; [email protected] (R.M.); [email protected] (G.L.S.); [email protected] (A.M.) * Correspondence: [email protected]; Tel.: +43-662-2420-80564 Received: 10 February 2018; Accepted: 21 March 2018; Published: 23 March 2018 Abstract: Cnidaria include the most venomous animals of the world. Among Cnidaria, Scyphozoa (true jellyfish) are ubiquitous, abundant, and often come into accidental contact with humans and, therefore, represent a threat for public health and safety. The venom of Scyphozoa is a complex mixture of bioactive substances—including thermolabile enzymes such as phospholipases, metalloproteinases, and, possibly, pore-forming proteins—and is only partially characterized. Scyphozoan stings may lead to local and systemic reactions via toxic and immunological mechanisms; some of these reactions may represent a medical emergency. However, the adoption of safe and efficacious first aid measures for jellyfish stings is hampered by the diffusion of folk remedies, anecdotal reports, and lack of consensus in the scientific literature. Species-specific differences may hinder the identification of treatments that work for all stings. However, rinsing the sting site with vinegar (5% acetic acid) and the application of heat (hot pack/immersion in hot water) or lidocaine appear to be substantiated by evidence. Controlled clinical trials or reliable models of envenomation are warranted to confirm the efficacy and safety of these approaches and identify possible species-specific exceptions. Knowledge of the precise composition of Scyphozoa venom may open the way to molecule-oriented therapies in the future. Keywords: Scyphozoa; nematocysts; toxin; venom; sting; first aid Key Contribution: The adoption of rationale first aid measures for the treatment of Scyphozoa stings is hindered by lack of consensus or evidence in the scientific literature. This review identifies rinsing the sting site with vinegar (5% acetic acid) and the application of heat (hot pack/immersion in hot water) or lidocaine on the sting site as safe and effective. Avoid rinsing the sting site with urine, distilled or plain water and seawater is recommended. 1. Introduction Cnidarians (Hatschek, 1888) are one of the oldest phyla and have existed since at least the Cambrian [1]. These venomous animals are widespread in tropical and temperate oceans and seas, with very few freshwater species [2]. The consensus among taxonomists is that five classes should be included in this phylum: Anthozoa, Cubozoa, Hydrozoa, Scyphozoa, and Staurozoa [3–5]. Anthozoa are represented by sea anemones and corals and are sessile organisms in adult life. Conversely, in the last classes, which constitute the subphylum Medusozoa, the sexual form is generally represented by a free-living medusa, with the exception of Staurozoa, that are regarded as benthonic medusae [6]. Toxins 2018, 10, 133; doi:10.3390/toxins10040133 www.mdpi.com/journal/toxins Toxins 2018, 10, 133 2 of 21 WithToxins 2018 more, 10, thanx FOR P 10,000EER REVIEW existing species, cnidarians are characterized by great biodiversity2 of 21 [7]. However, a characteristic common feature of these animals is the nematocyte, a cell type unique to this phylum.With Nematocytes more than 10,000 contain existing an extrusive species, cnidarians organoid, are the characterized nematocyst by (Figure great1 biodiversity), derived from [7]. the However, a characteristic common feature of these animals is the nematocyte, a cell type unique to Golgi complex [6,8]. this phylum. Nematocytes contain an extrusive organoid, the nematocyst (Figure 1), derived from Nematocysts are used for prey capture, defense, spatial competition, and locomotion and may the Golgi complex [6,8]. differ in sizeNematocysts and shape are betweenused for prey species capture, and defense, also within spatial the competition same species., and locomotion There have and been may 25 to 30 typesdiffer described in size and according shape between to morphological species and also properties within the [9 same,10]. species. Invariably, There they have present been 25 a to common 30 structuretypes consisting described ofaccording a cylindrical to morphological capsule closed properties by an operculum[9,10]. Invariably and containing, they present an inverteda common tubule immersedstructure in anconsisting aqueous of solution a cylindrical with capsule a complex closed mixture by an ofop toxins.erculum Following and containing mechanical–chemical an inverted stimulation,tubule immersed the tubule in an is quicklyaqueous everted,solution with thus a injecting complex intomixture the of teguments toxins. Following of the preymechanical or predator– the venomouschemical stimulation, substances. the This tubule event is quickly is called everted, discharge thus andinjecting is known into the as teguments one of the of fastest the prey processes or in thepredator animal the kingdom venomous [8,11 sub,12stances.]. Recent This studies event is reveal called discharge that a novel and elastic is known protein, as one similarof the fastest to that of processes in the animal kingdom [8,11,12]. Recent studies reveal that a novel elastic protein, similar spider silk, may be the molecular determinant of kinetic energy storage and release during nematocyst to that of spider silk, may be the molecular determinant of kinetic energy storage and release during discharge [13]. nematocyst discharge [13]. 25 µm 25 µm (a) (b) FigureFigure 1. 1. PhasePhase contrastcontrast microphotographsmicrophotographs of of(a () a)undischarged undischarged and and (b) (bdischarged) discharged holotrichous-isorhizaholotrichous-isorhiza nematocysts nematocysts isolated isolated from from PelagiaPelagia noctiluca (Cnidaria:(Cnidaria: Scyphozoa) Scyphozoa) oraloral arms. arms. Being present in both coastal and open waters at different depths, cnidarians often come into Beingaccidental present contact in with both humans coastal, andinterfer opening with waters human at different activities depths,and consequently cnidarians hav oftening a come into accidentalconsiderable contact impact on with public humans, safety, interferinghealth, and economy. with human People activities engaged andin recrea consequentlytional aquatic having a considerableactivities, such impact as swimmers, on public surfers safety, and health, divers, and might economy. be exposed People to cnidarian engaged stings. in recreational With specific aquatic activities,regard such to Scyphozoa, as swimmers, abundant surfers blooming and divers, of some might species be exposed observed to cnidarianin the last stings. decade With in the specific regardNortheast to Scyphozoa, Atlantic abundant and the Mediterranean blooming of someand in speciesthe coastal observed areas of in Korea, the last China decade, and in Japan the Northeasthave Atlanticdiscouraged and the Mediterraneantourists and markedly and in interfered the coastal with areas fishing of and Korea, aquaculture, China, and thus Japan causing have substantial discouraged touristseconomic and markedly burden to interferedcoastal economies with fishing [14–22]. and aquaculture, thus causing substantial economic Concerning the impact of cnidarians on human health, the potentially lethal Chironex fleckeri burden to coastal economies [14–22]. (Cnidaria: Cubozoa), Carukia barnesi (Cnidaria: Cubozoa), and Physalia species (Cnidaria: Hydrozoa) Concerning the impact of cnidarians on human health, the potentially lethal Chironex fleckeri are considered to be the most venomous among the Medusozoa [23–25]. Although the Scyphozoa (Cnidaria:are generally Cubozoa), consideredCarukia barnesiless dangerous,(Cnidaria: they Cubozoa), are responsible and Physalia for speciesthe majority (Cnidaria: of jellyfish Hydrozoa) are consideredenvenomations to be throughout the most venomous the world and among life-threatening the Medusozoa complications [23–25]. Althoughfollowing this the occurrence Scyphozoa are generallyare possible considered [26]. The less lay dangerous, press, anecdotal they are reports responsible, and various for the information majority of accessible jellyfish through envenomations the throughoutweb concerning the world first and aid life-threatening measures for jellyfish complications stings are followingoften confusing this occurrence and contradictory. are possible This [26]. The laymay press, lead to anecdotal the adoption reports, of remedies and various that are information ineffective accessibleor harmful throughand may thedelay web or concerningimpede the first aid measuresapplication for of jellyfish more rationale stings measures are often of confusing intervention. and In contradictory. addition, there This is no may consensus lead to among the adoption the of remediesscientific that reports are ineffectiveon this subject, orharmful which is anda matter may of delay intense or debate impede [27 the–31]. application Therefore, the of moreaim of rationale the present work is to give an overview of the first aid