Migration, development, and condition of Trichobilharzia ocellata (Trematoda: Schistosomatidae) in homologous challenge infections

Abstract

Migration, development, and condition ofTrichobilharzia ocel!ata (Trematoda: Schistosomatidae) in homologous challenge infections. Can. J. Zool. 53: 1803-181 1. Ducks previously infected with Trichohilhar& rrceZ1ara were challenged by exposum to conspecific cercariae. Comparisons were made among worms recowred from teased or squashed tissue or locared in sections, after first, second, or multiple challenges. Contrasting with 24 h clearance in initial infections. schisrosomuIa were retained in the skins of challenged birds, mainly in the stratum corneum, for up to 7 days. Pdrasites reached the lungs as early as day 1 in first and second c hallenges but more than 50% bf these were adhering to brc~nchial wall? in mucoid material. After thlrd challenpe. wormswere seen in the l u n a~n davs 3-7 b u~ 35-H3%of these were coated with lymphoid ce~s.-Schistosomula were found in ;fie liver5 of 16/19. 411 5 , and 2120 birds examined aner firql, second, and multiple challenges respectively, most being in sinusoids surrounded by lymphocytes. No worm\ assignxble to challenge infecl~ons were found in the hosts' inlestinal veins. Parasites which survived 7 days in challenge infections reached lengths of about 300 pm. shout I k 1 5 % of the normal value. Those from 16\19 birds retained cercarial features such as tegumental spines, eyespots, and head organs.

The severity of mouse pathologies caused by the bird schistosome Trichobilharzia regenti in relation to host immune status

“…H&E, bar 75 lm which only led to an increase in the number of schistosomula trapped in the skin, the complete elimination of all the parasites in the skin was observed only in animals challenged ten times. Similar results were reported by Von Lichtenberg and Ritchie (1961) and Ellis et al (1975) who studied the efficacy compatible host immune response during primary and challenge infections with Schistosoma mansoni and T. ocellata infections, respectively. It seems, therefore, that effective killing of the schistosome larvae in the skin represents a common effect during host reinfection with cercariae.…”

Snails, waterfowl and cercarial dermatitis

“…Modes of migration of visceral and nasal schistosomes differ, and therefore, different organs/tissues can be impaired. Severity of infection depends on parasite behaviour, worm load and host immune status (Bourns, Ellis & Rau, 1973; Ellis, Bourns & Rau, 1975; Rau, Bourns & Ellis, 1975; Pennycott, 1998; Horák et al. , 2002; Van Bolhuis et al.…”

“…szidati revealed that schistosomula leave blood vessels and break into the air spaces (Bourns et al. , 1973; Ellis et al. , 1975; Chanová, Vuong & Horák, 2007).…”

The occurrence of the avian schistosome Allobilharzia visceralis Kolářová, Rudolfová, Hampl et Skírnisson, 2006 (Schistosomatidae) in the tundra swan, Cygnus columbianus (Anatidae), from North America

“…Therefore, by breeding age these swans may have been infected for a minimum of three years. It is not known at this time if adults have acquired immunity and can become infected as adults (Ellis et al 1975).…”