Snails, waterfowl and cercarial dermatitis

Abstract

1. Birds and snails are suitable hosts for many parasites, including helminths in general and trematodes in particular. Among trematodes, members of the family Schistosomatidae with two-host life cycles (snails as intermediate hosts and birds as definitive hosts) are successful and abundant pathogens. Their transmission between birds and snails in nature can be influenced by many abiotic and biotic factors. 2. In snails, the prevalence of schistosome infections and production of cercariae can be influenced by host immunological susceptibility ⁄ physiological suitability, snail age ⁄ size, interspecific competition of trematode larvae, etc. Schistosomes are able to survive in overwintering snails, serving as a source of infection in spring. 3. Birds may also differ in susceptibility to and prevalence rates of schistosome infections. They are long-range vectors of schistosomes. 4. Climate changes influence behaviour of migratory birds, lead to shifts in season-or temperature-dependent processes in snails and schistosomes, and influence the frequency of schistosome transmission and intensity of infection. Also, eutrophication can increase the growth of snail populations and transmission of bird schistosomes. 5. Dispersal of bird schistosomes to new regions and an increased availability (local abundance) of the snail hosts, together with the use of new water reservoirs (e.g., in higher latitudes) for recreational purposes, may contribute to a higher number of outbreaks of cercarial dermatitis.

Avian Schistosomes and Outbreaks of Cercarial Dermatitis

“…from Radix peregra (275). In addition, a link has been suggested between the rise of 0.8°C within the last century and the increased frequency of cercarial dermatitis and Trichobilharzia prevalence at higher latitudes in Europe (9,276). What does not change is the life span of cercariae, which is limited to the restricted source of reserve glycogen (cercariae do not take up any food).…”

“…Older reports refer to 75% or more of the population experiencing the characteristic symptoms of "koganbyo" in the areas of Japan where the disease is most highly endemic (5). Recent reviews (6)(7)(8)(9) agree that in some regions cercarial dermatitis has appeared as a new problem, either because the dermatitis was previously unknown (e.g., the U.S. Southwest and Chile) or because the number of reports of outbreaks increased (8,10,11). Consequently, cercarial dermatitis is now regarded as an emerging disease.…”

Radix spp.: Identification of trematode intermediate hosts in the Czech Republic

“…Cercarial dermatitis is considered to be a re-emerging disease, causing severe problems in recreational areas in all around the world (Horák and Kolářová 2011). Fascioloides magna (Bassi, 1875) was originally distributed in North America, but recently has spread in Europe and its veterinary importance is growing also in the Czech Republic (Novobilský et al 2007).…”

Larval trematodes in freshwater gastropods from Mato Grosso, Brazil: diversity and host-parasites relationships

“…13,no. 4 Discussion Among the infected snails B. amazonica, D. lucidum and P. maculata should be detached because harbored Brevifurcate apharyngeate cercaria that can cause human dermatitis (Horák & Kolárová 2011, Bosnia et al 1990, Hanning & Leedom 1978. Cases of human dermatitis in Brazil may be underestimated because some species of trematodes have been found in birds and intermediate hosts widely distributed throughout the country (Pinto et al 2012).…”