View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Bern Open Repository and Information System (BORIS) Original article | Published 4 September 2013, doi:10.4414/smw.2013.13877 Cite this as: Swiss Med Wkly. 2013;143:w13877 Swiss prospective study on spider bites Markus Gnädingera, Wolfgang Nentwigb, Joan Fuchsc, Alessandro Ceschic,d a Department of General Practice, University Hospital, Zurich, Switzerland b Institute of Ecology and Evolution, University of Bern, Switzerland c Swiss Toxicological Information Centre, Associated Institute of the University of Zurich, Switzerland d Department of Clinical Pharmacology and Toxicology, University Hospital Zurich, Switzerland Summary per year for acute spider bites, with a peak in the summer season with approximately 5–6 enquiries per month. This Knowledge of spider bites in Central Europe derives compares to about 90 annual enquiries for hymenopteran mainly from anecdotal case presentations; therefore we stings. aimed to collect cases systematically. From June 2011 to The few and only anecdotal publications about spider bites November 2012 we prospectively collected 17 cases of al- in Europe have been reviewed by Maretic & Lebez (1979) leged spider bites, and together with two spontaneous no- [2]. Since then only scattered information on spider bites tifications later on, our database totaled 19 cases. Among has appeared [3, 4] so this situation prompted us to collect them, eight cases could be verified. The causative species cases systematically for Switzerland. were: Cheiracanthium punctorium (3), Zoropsis spinimana (2), Amaurobius ferox, Tegenaria atrica and Malthonica Aim of the study ferruginea (1 each). Clinical presentation was generally mild, with the exception of Cheiracanthium punctorium, Main objective: To systematically document the clinical and patients recovered fully without sequelae. course of spider bites in Switzerland. In Switzerland, spider bites generally have a benign clinical Secondary objectives: To collect information on causative course, which is characterised by minor effects, with rapid species, time of day, seasonal distribution, and circum- and complete recovery. Since only verified spider bites can stances. be regarded as spider bites, in the case of clinically import- ant arachnidism, the spider should be sent to an expert for Methods identification. Our study may help to diminish spider fear and reassure people who have experienced a bite. In a prospective, observational study, patients were in- The study was registered at ClinicalTrials.gov cluded who had suspected spider bites and consulted a (NCT01355744). Swiss physician. The study was planned to take place between 1 June and 30 November 2011, but was then pro- Key words: insect bites; spider bites; humans; longed until 30 November 2012 to include more cases in Switzerland; Middle Europe; case reports our study set. In order to inform both Swiss physicians and | downloaded: 13.3.2017 the Swiss population, the study kick-off was accompanied Introduction by a media campaign. The reporting forms were sent by fax to the Swiss Toxic- In Switzerland, the number of spider species theoretically ological Information Centre and the following items were able to bite humans amounts to a few dozen among the registered about the people who had allegedly been bitten: nearly 1,000 species found in this country [1]. Despite year of birth, gender and health situation, time, place (in- mostly minor clinical symptoms, the general population cluding altitude) and circumstances of the bite, the body may frequently overestimate the danger of spider bites. Ad- part involved, symptoms, signs, clinical course (incl. photo ditionally, primary care physicians’ knowledge of spider documentation) and treatment. The spider had to be caught bites is limited, because cases of spider bite consultations and sent to the Institute of Ecology and Evolution at the are quite rare. There are no useful data for estimating the University of Bern for identification by an expert arachno- incidence of spider bites in Switzerland or for providing logist (WN). The specimens had to be sent alive or in 70% helpful information about their clinical course. This in- ethanol vials. In case of ambiguity or incomplete record- formation is also lacking for other central European coun- http://boris.unibe.ch/47906/ ings, MG contacted the reporting physician. Every physi- tries. cian who participated received CHF 100.–. Between 2000 and 2010, the Swiss Toxicological Inform- ation Centre (STIC) received approximately 30 enquiries source: Swiss Medical Weekly · PDF of the online version · www.smw.ch Page 1 of 12 Original article Swiss Med Wkly. 2013;143:w13877 According to international standards [5] spider bites can Results only be classified as verified when three circumstances have been fulfilled: (1) The spider bite has been observed, During the study period, seventeen cases of alleged spider (2) the spider is caught during or immediately after the bite bites were reported. Together with two cases fulfilling the and sent for identification, and (3) the case presentation inclusion criteria, which occurred shortly after the end of matches the clinical course of a bite by a spider through the study period and which were spontaneously reported by symptoms such as pain or discomfort. a physician and therefore included in the study, we received Data were entered into a standardised Excel spreadsheet 19 notifications. Only eight cases fulfilled the criteria men- (Microsoft Corporation, Redmond, WA) and descriptive tioned above to be regarded as verified spider bites, and are statistics were calculated. If not stated otherwise, data are therefore described in detail in this publication. Detailed presented as median (interquartile range, IQR). data on the other 11 cases of assumed spider bites can be Written informed consent was obtained. requested from MG. All ethics committees of Switzerland and the Principality Demographic data of the patients and a general description of Liechtenstein approved the study. of their clinical course are summarised in table 1. Figure 1 shows the leg of case one shortly after the bite, notably the reddening and the central haemorrhage. Six cases were allocated to the study by calls to the Swiss Toxicological Information Centre (cases 1, 6, 9, 11, 14 and 17); the victims in two cases (7, 19) contacted our study board on their own. The initial physician contacts were a family physician (1), a duty physician (1), and hospital (3) or other (2) physicians (one case had missing information); study notifications were sent to us from a family physician (1), hospital physicians (4) or others (3). Five patients re- ported that they had seen the spider while being bitten. In- terestingly, no tropical spider owners were included in this study. Two patients reported previous knowledge about the possibility of spider bites in Switzerland, while five did not (one answer is missing). All patients said that it was the first time they had been bitten by a spider. Two of them re- cognised spider cocoons at the place where they had been bitten, while five did not (one missing answer). One out of eight suffered from systemic symptoms. This concerned a female patient who had to undergo hospital surveillance for approximately 12 hours (case 6). The re- ported systemic symptoms were hypotension, vomiting, and generalised itching. The patient was treated with ibuprofen, acetaminophen, tramadol, morphine, and meto- clopramide. Figure 1 Pain quality reports were burning (4), piercing (2), itching Leg of patient 1, two hours after bite by Amaurobius ferox. (1) or dull (1). No necrosis at the bite site was reported. One case of a small (3 mm) haemorrhage at the site of the Table 1: Characteristics of patients and their clinical presentation. bite was registered. Bite marks were observed in three out Numbers denote median value (interquartile range) or frequencies. of seven patients (one missing report). As treatment meas- Gender (female/male) 5/3 Age (years) 41 (32) Area of spider bite – upper extremity 6 – lower extremity 1 – torso 1 Diameter (mm) of maximum – swelling 20 (56) – reddening 20 (30) Pain – severity (0 to 10) 4 (7) – time until maximum (minutes) 0 (1) – duration (hours) 1 (7) – comparison with bee sting (less / equal / more 4 / 1 / 2 / 1 / missing) Time until – first consultation (hours) 2 (1) Figure 2 – complete healing (days) 3 (5) Amaurobius ferox, male (source: Fritz Geller-Grimm, Wikimedia Presence of systemic symptoms (no / yes / 6 / 1 / 1 Commons). missing) Swiss Medical Weekly · PDF of the online version · www.smw.ch Page 2 of 12 Original article Swiss Med Wkly. 2013;143:w13877 ures, we registered analgesics (1), a tetanus vaccine (1), Discussion and other symptomatic measures (3). Two of the patients stated that they would have contacted a The outdoor bites occurred mainly in the summertime; physician because of the severity of their complaints even bites by adult Zoropsis spinimana occurred also in Novem- without the study, while for five this was not the case (one ber and December. There are no obvious detectable pat- missing report). terns with respect to the time of the day, part of the country, Table 2 shows the temporal and geographical distribution or elevation, i.e., spider bites can occur everywhere. The of the bites. Table 3 lists the causative spider species. Fig- spider bites described in our study were, however, restric- ures 2 to 6 depict spider species caught in our study. ted to buildings and their surroundings, where people get To approach the question whether bites by Cheiracanthium into unintentional contact with spiders during all kind of punctorium display a more severe course, we compared activities such as sleeping, working or leisure. In our study, these three cases with the other five: average pain severity transportation of the spider in the hand was the reason for 9 vs 3 points (on a scale from 0 to 10), swelling 30 mm vs 6 three bites, in two occasions putting on clothes in which mm, reddening 30 mm vs 10 mm, healing duration 4 days vs 1 day.