title: New scope on the relationship between rotifers and Biomphalaria alexandrina snails.
abstract: OBJECTIVE
  To investigate the effect of rotifer internalization into snail tissue on the development of schistosomes.
  
  
  METHODS
  Susceptible laboratory-bred Biomphalaria alexandrina (B. alexandrina) snails were exposed to lab-maintained rotifers; Philodina spp., two weeks before and after being infected with Schistosoma mansoni (S. mansoni) miracidia. The consequent histopathological impact on snail tissues and cercarial biology were investigated before and after emergence from snails.
  
  
  RESULTS
  Contamination of B. alexandrina snails with philodina, two weeks before miracidial exposure, was found to hinder the preliminary development of S. mansoni cercariae inside the snail tissues. Furthermore, when snails were contaminated with rotifers two weeks post miracidial exposure; growth of already established cercariae was found to be retarded. The consequent influence of internalized rotifers within the snail tissue was clearly reflected on cercarial emergence, activity and infectivity along the four weeks duration of shedding. In the present study, comparison of snail histopathological findings and altered cercarial biology observed between the experimental and control groups indicated that the rotifers may have affected the levels of snail's energy reservoirs, which eventually was found to have had an adverse impact on reproduction, growth and survival of the parasite within the snail host, coupled with its performance outside the snail.
  
  
  CONCLUSIONS
  In future biological control strategies of schistosomiasis, ritifers should be considered as a parasitic scourge of humanity.
authors.affiliation: Medical Parasitology Department, Faculty of Medicine, Alexandria University, Egypt. mossallamsh@hotmail.com
authors.forename: Shereen Farouk
authors.initials: SF
authors.lastname: Mossallam
authors.forename: Eglal Ibrahim
authors.initials: EI
authors.lastname: Amer
authors.forename: Iman Fathy
authors.initials: IF
authors.lastname: Abou-El-Naga
mesh_terms: D000818:Animals; D001700:Biomphalaria / Q000469:parasitology* / Q000502:physiology*; D058487:Cercaria / Q000254:growth & development / Q000502:physiology; D006790:Host-Parasite Interactions; D059208:Parasite Load; D012403:Rotifera / Q000502:physiology*; D012550:Schistosoma mansoni / Q000254:growth & development / Q000502:physiology*; D013559:Symbiosis
keywords: Biomphalaria alexandrina; Cercarial biology; Rotifers; Schistosoma mansoni; Snail histopathology
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