Short Communication Wien Klin Wochenschr (2006) 118 [Suppl 3]: 77–80 DOI 10.1007/s00508-006-0674-2 © Springer-Verlag 2006
WIENER KLINISCHE WOCHENSCHRIFT The Middle European Journal of Medicine Printed in Austria
Cercarial dermatitis in Austria: Questionnaires as useful tools to estimate risk factors? Christoph Hörweg1, Helmut Sattmann1, and Herbert Auer2 Natural History Museum Vienna, Department of Invertebrate Zoology, Vienna, Austria Institute of Hygiene and Medical Microbiology, Department of Medical Parasitology, Medical University of Vienna, Vienna, Austria 1
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Zerkariendermatitis in Österreich: Sind Erhebungsbögen zur Abschätzung von Risikofaktoren hilfreich? Zusammenfassung. Die Zerkariendermatitis ist eine durch Larvenstadien von Saugwürmern der Familie Schistosomatidae hervorgerufene und durch juckende Papeln charakterisierte Hautirritation. In den Tropen und Subtropen kommen auch humanspezifische Arten vor (Schistosoma), die außer der Dermatitis ernste Erkrankungen hervorrufen können, nämlich die Blasen- und die Darmbilharziose. In Europa parasitieren die meisten Arten der Schistosomatidae in Vögeln (Trichobilharzia, Bilharziella), sie werden auch als Vogelbilharzien bezeichnet. Wasserlungenschnecken dienen als Zwischenwirte. Der Mensch wird zufällig befallen, indem die aus den Schnecken schlüpfenden Larven (Zerkarien) in die Haut von im Wasser Befindlichen eindringen. Diese Larven entwickeln sich im Fehlwirt Mensch nicht weiter, sondern sterben bald nach dem Eindringen ab. Die Zerkariendermatitis ist in Österreich seit dem Jahre 1969 bekannt. Seither konnten immer wieder Krankheitsfälle beobachtet und registriert werden. Im Frühsommer 2003 wurde eine Homepage erstellt, um betroffenen Patienten einerseits Wissenswertes über die Biologie und Ökologie der Erreger der Zerkariendermatitis zur Verfügung zu stellen, und andererseits, um über einen Fragebogen Daten über Häufigkeit und Verbreitung dieser Parasitose in Österreich zu erheben. Mittels dieses Erhebungsbogens baten wir Betroffene um persönliche Daten, Angaben zum Gewässer, Angaben zum Aufenthalt im Wasser sowie zur Symptomatik der Dermatitis. Es konnten insgesamt 34 Erhebungsbögen ausgewertet werden. Die oft nicht ganz einfach zu interpretierenden Ergebnisse werden hinsichtlich etwaiger Risikofaktoren diskutiert. Demographische Faktoren scheinen keine Rolle zu spielen, sondern vielmehr entscheidet die Interaktion mit dem Wasser über die Häufigkeit des Auftretens von Zerkariendermatitis. Benützer von Garten-Schwimmteichen konnten als bis jetzt noch nicht in Erscheinung getretene Risikogruppe ausgemacht werden.
Summary. Cercarial dermatitis is a worldwide occurring skin disease characterized by itching and skin papulation. It is caused by cercariae of the fluke family Schistosomatidae. In the tropics and subtropics species of the genus Schistosoma can cause severe diseases of man. However, several genera (e.g. Trichobilharzia, Bilharziella) of medical significance are prevalent in Europe as well; they are also known as “bird schistosomes”, because waterfowl is the final host. Pulmonate snails act as intermediate hosts. Humans are accidental hosts; they get infested by penetration of the cercariae into the skin of swimmers/bathers in ponds and lakes. They can not mature in humans, but die shortly after penetration. Cercarial dermatitis is known in Austria since 1969, with regularly occurrences nearly every summer. In early 2003 we created a homepage to provide information about the causative agents for the public/patients, to document the occurrences and to get data about the distribution of this parasitic disease. We therefore created a questionnaire and asked people for the following parameters: personal data, information about the waters, activity in the water and details about the dermatitis itself. A total of 34 questionnaires were returned. The results will be discussed according to their relevance as risk factors. The way how people interact with the water seems to be essential, but not demographic features. In addition, this approach revealed a new segment of the public that is at risk – owners/users of swimming ponds. Key words: Cercarial dermatitis, questionnaire, risk factors, Austria.
Introduction Cercarial dermatitis is a worldwide occurring and often neglected skin disease characterized by itching and skin papulation. It is caused by larval stages (cercariae) of the fluke family Schistosomatidae. In the tropics and subtropics species of the genus Schistosoma can cause – in addition to the dermatitis – severe diseases of man, i. e. intestinal and urinary bilharziosis. However, five genera (Orientobilharzia, Dendritobilharzia, Bilharziella, Tricho
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bilharzia, Gigantobilharzia) of medical significance are prevalent in Europe as well [1, 2]; they are also known as “bird schistosomes”, because waterfowl is the final host. Pulmonate snails act as intermediate hosts. Humans are accidental hosts; they get infested by penetration of the cercariae into the skin of swimmers/bathers in ponds and lakes. Cercarial dermatitis has been known in Austria since 1969 [3, 4]. In nearly all provinces cases of this helminthic disease could be observed in increasing numbers during the last years [5–9]. Thus, cercarial dermatitis has to be considered an emerging disease in Central Europe nowadays [10, 11]. In Austria only Trichobilharzia szidati (from Lym naea stagnalis) and Bilharziella polonica (from Planor barius corneus) are proof records [7]. Furthermore, Trichobilharzia sp. had been recorded from Lymnaea stagnalis, Stagnicola turricola, Stagnicola sp., Radix auri cularia and Radix ovata. Schistosomatid cercariae were also recorded from Aplexa hypnorum (snails of the family Physidae) and Gyraulus parvus (Planorbidae) [9]. Due to the fact that our knowledge about human incidence and risk factors is rather limited in Central Europe [12] and even in the world [13–15], a website [16] was created in spring 2003 with information for persons concerned, combined with the option to download a questionnaire to provide us with first-hand information. Thus, we expected to gain not only information on prevalence, incidence and distribution of cercarial dermatitis in Austria to get an idea about possible risk factors, but also to have a chance to proof evidence of the causative agents and snail hosts involved. As cercarial dermatitis is not notifiable and no networks between dermatologists and/or family doctors exist, questionnaires seemed to be a promising method.
Materials and methods Via a questionnaire located at www.helminths.at/zd/ badederm.html data were collected, including contact details, information about the waters, information about the duration of stay in water plus preventive actions and details about the dermatitis itself. For the detailed parameters see Fig. 1.
Results In total, 34 questionnaires were returned. For the detailed investigated data including results see Fig. 1. The age distribution ranged from 6 to 75 years, with most people aged between 30 and 50. The male to female ratio was 18 to 16. Most questionnaires were returned from Austria, some from Germany and one from Switzerland. The Austrian ones were all from the Eastern part, mainly from Lower Austria. Records from natural waters, quarry ponds, swimming ponds and bayous were involved. In most cases the presence of water plants was recorded, in all cases waterfowl was observed and a third of the clients noticed water snails. Cases of swimmer’s itch were recorded from May to August. The time of day people mostly frequented the water was the afternoon. The estimated or recorded air-temperature ranged from 24 °C up to 40 °C and the water-temperature from
19 °C up to 28 °C. The time people have spent in the water ranged from 5 minutes up to 4 hours. The activities included swimming, playing and working. 5 persons applied lotion before entering the water and 21 persons rubbed their bodies dry after their stay in water. The most affected body parts were torso, arms and legs. In most cases a severe itching occurred. In four cases other symptoms have been reported: big red spots, swelling of the lymph nodes, general disturbance and severe depression. The duration of the dermatitis ranged from one day up to three weeks with a variable course. People, who sought consultation, went to family doctors, pharmacies, dermatologists and a hospital.
Discussion Questionnaires are tools easy to provide but difficult to interpret because researchers must rely on the data transmitted. But they are a promising inexpensive tool to get as much information as possible from a broad range of people within a relatively short period of time. As one important point, this study found owners/users of swimming ponds to be a “new” (i.e. currently unknown or at least underestimated) risk group. Because of the nearnatural habitat, many swimming ponds have abundant water plants and water snails. As waterfowl (in most cases ducks were reported) rest – even if only briefly – at such small water bodies, the life cycle of bird schistosomes can be fulfilled. Furthermore, people use their swimming pond not only for swimming, but they also take care of their pond, for example by “gardening” activities. According to Verbrugge [14], bathers should avoid using shallow water. In many cases, people used sandy, muddy, but in almost all cases flat shores to enter the water. If they do choose such places, the less often, the better. Despite our small sample size, we can summarize – again in accordance with Verbrugge [15] – that the onset and severity of swimmer’s itch are affected by how people interact with the lake, not by their demographic features. Thus, there were no significant differences between age groups or gender. Waterfowl and water snails are essential for the lifecycle. Therefore it can be recommended to hold off water birds and to reduce water plants to pejorate the life conditions of the intermediate snail hosts. Occurrences of cercarial dermatitis started in May and went through till August with most cases reported in August. This is not uncommon and confirms existing data. The most entries into the water happened in the afternoon which can be a result of “after-work bathing” people. Furthermore, the air- and water-temperatures in the afternoon might be more convenient for bathers, thus being the “prime-time”. The duration of stay in water and the kind of activity are not significant, but it can be assumed, that longer stays in shallow water increases the probability of infection. It is often recommended to use (sun-)lotions before exposure and to rub oneself dry after exposure, with no conspicuous effect. But there is a bright spot: German scientists created a sun lotion containing an antihelminthic drug which might be available at German pharmacies [17].
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Fig. 1. Cercarial Dermatitis Questionnaire – investigated data including evaluable factors and results (n = 34)
More studies of cercarial dermatitis in Austria are needed. Study designs that combine epidemiologic and biological data will simultaneously inform public health authorities and help to solve open questions concerning the species spectrum involved.
Acknowledgements First of all, we would like to thank those persons who provided us with the questionnaires. Furthermore, we thank Dr. Robert Konecny (Umweltbundesamt, Vienna) for the discussions and the useful hints he gave and an anonymous reviewer for valuable instructions.
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[email protected]
