Swimmer's Itch in Belgium: First Recorded Outbreaks, Molecular Identification of the Parasite Species and Intermediate Hosts

Abstract

Background: Cercarial dermatitis or swimmer's itch is a skin condition in humans due to the larval forms of bird schistosomes of some species of the genus Trichobilharzia. The life cycle of these schistosomes requires freshwater snails (intermediate host) and waterfowl (definitive host). Repeated exposures to cercariae can lead to skin sensitization with the induction of pruritic skin lesions. Methods: We describe, in this study, two outbreaks of human cercarial dermatitis at the Eau d'Heure Lakes, Belgium. In July and August 2012, a total of, respectively, 78 and 10 people reported a sudden skin rash accompanied by pruritus following recreational activities in the Plate Taille Lake. However, no ocellate furcocercariae were detected following light exposure of the snails collected between September 2012 and September 2013 (n = 402). No outbreaks were recorded in 2013 and 2014. In August 2015, about 30 new cases were recorded. Snails were collected (n = 270) in different locations around the lake. PCR was used to identify accurately the intermediate hosts and the parasite species involved. Results: After light exposure, seven Radix spp. (2.6%) shed ocellate furcocercariae. Molecular identification based on the rDNA internal transcribed spacer 2 sequence ascribed the infected snails to R. balthica ( = R. peregra = R. ovata) (6/7) and R. auricularia (1/7). Based on the amplification of the D2 domain of the 28S rDNA, the cercariae were shown to belong to two different haplotypes of Trichobilharzia franki. Conclusions: This is the first record in Belgium of T. franki and associated skin condition.

Outbreak of swimmer's itch in Central Italy: Description, causative agent and preventive measures

“…The minimum infectious rate in snails observed in the present study (2.1%) is in the range of values reported in literature (Caron et al, ; Horák & Kolářová, ; Horák et al, ), but lower to the prevalence of 9.6% observed in R. auricularia from Vico Lake. Higher values are seldom reported in eutrophic environments (Soldánová, Faltýnková, Scholz, & Kostadinova, ).…”

“…Swimmer's itch, or cercarial dermatitis, is a pathological condition caused by the penetration of free‐swimming larvae (cercariae) of trematodes of the family Schistosomatidae in human skin, provoking an allergic inflammatory response normally limited at outer dermal layers (Soldánová, Selbach, Kalbe, Kostadinova, & Sures, ). Due to its allergic component, cercarial dermatitis usually develops after repeated contacts with the parasite and consequent host sensitization (Caron, Cabaraux, Marechal, & Losson, ). Following increasing reports from many European countries, swimmer's itch is nowadays considered an emerging disease in the continent (Soldánová et al, ).…”

“…At present, in Europe, foci of swimmer's itch have been reported from Czech Republic (Kolářová, Horák, & Sitko, ), Switzerland (Chamot, Toscani, & Rougemont, ), Poland (Zbikowska, ), France (Jouet et al, ), the Netherlands (Schets, Lodder, Duynhoven, & Roda Husman, ), England (Lawton et al, ), Germany (Selbach et al, ) and Belgium (Caron et al, ). In Italy, it was first reported in the lake of Garda (northern Italy) in 1998 (Golo et al, ) and, more recently, in central Italy in the lake of Vico, where Cipriani et al () identified the species T. franki as the causative agent of the dermatitis and R. auricularia as its intermediate host.…”

Agents of swimmer’s itch—dangerous minority in the Digenea invasion of Lymnaeidae in water bodies and the first report of Trichobilharzia regenti in Poland

“…Many digenetic trematodes pose threat to animal and human health (Cheng 1986 ). These parasites include bird schistosomes, whose invasion on humans has been recently reported in many countries (Rao et al 2007 ; Valdovinos and Balboa 2008 ; Gohardehi et al 2013 ; Marie et al 2015 ; Marszewska et al 2016 ; Caron et al 2017 ). The disease caused by cercariae of these trematodes occurs globally and is considered to be re-emerging (Kolářová et al 2010 ).…”

Swimmer’s itch in Canada: a look at the past and a survey of the present to plan for the future

“…Other reports from the literature tend to find higher prevalence of schistosomes among snails, although in general less snails are collected and examined, and reports are from a single time point (e.g. 1.24–1.8% in Poland, 3456 and 299 snails examined, respectively [ 40 , 41 ]; 0.9–1.3% in Argentina, 402 snails examined [ 28 ]; 2.6% in Belgium, 270 snails examined [ 42 ]). Nevertheless, if the rate of prevalence for schistosomes in snails uncovered through this study is indicative of that for lakes across Alberta, or elsewhere, this holds significance for control measures.…”