Genetic diversity of an avian nasal schistosome causing cercarial dermatitis in the Black Sea-Mediterranean migratory route.

This study is part of an effort to document the diversity of avian schistosomes in ducks and snails in Northern Iran, a major flyway (Black Sea/Mediterranean) for migratory birds and where cercarial dermatitis (CD) is prevalent in rice growing areas. CD is an allergic skin reaction from schistosome trematodes that emerge from aquatic snails. Most CD cases are reported from recreational swimmers or aquaculture farmers. Much of the work on the epidemiology of CD has focused in recreational waters in the Americas and Europe, with fewer studies in aquaculture, particularly in Iran. The artificial environment at aquaculture sites support dense populations of snails that are hosts to schistosomes, as well as domestic ducks. Thus, are domestic ducks reservoir hosts of species of Trichobilharzia, one of the main etiological agents of CD in Northern Iran? This study focused on a survey of domestic ducks for the presence of the nasal schistosome, T. regenti, that has been reported widely in Europe. Trichobilharzia regenti were found in domestic ducks in the Guilan Province of Iran based on morphological and molecular analyses. The presence of this species in Northern Iran indicates that the domestic duck can serve as a reservoir host for this species and that one of the local snail species is likely the intermediate host. The continued study and surveillance of this species is important because it is a neuropathic schistosome that can use a diversity of bird definitive hosts and Radix snails that are widespread across Eurasia.