Treatment development for systemic Tetrahymena sp. infection in guppies, Poecilia reticulata Peters

M. Pimenta Leibowitz, J. Kumar Chettri, R. Ofir, D. Zilberg

Research output: Contribution to journalArticlepeer-review

8 Scopus citations


Antibacterial and antiparasitic agents and a cysteine protease inhibitor (E-64) were tested against Tetrahymena infection, a serious problem in guppy production worldwide. Chemicals were tested in vitro by a colorimetric assay for Tetrahymena survival. The most effective were niclosamide, albendazole and chloroquine, with 23%, 35% and 60% survival, respectively, following 2-h exposure to 100 ppm. Longer incubation periods resulted in greater reductions in survival. Niclosamide was further studied in vivo at different dosages, administered orally to Tetrahymena-infected guppies. Mortality rates were significantly lower in all treatment groups; in trial I, 30% and 33% mortality in 5 and 40 mg kg-1 niclosamide-fed fish vs. 59% mortality in controls; in trial II, 35%, 13% and 10% in 50, 100 and 200 mg kg-1 niclosamide-fed fish vs. 64% in controls. The effect of the cysteine protease inhibitor E64 was tested in tissue culture, by measuring histolytic activity of the parasite (Tet-NI) on a guppy-fin cell line, based on cell depletion. Tet-NI feeding activity was significantly reduced following pretreatment with E-64 relative to non-treated Tet-NI. E-64-pretreated Tet-NI was injected i.p. into guppies: recorded mortality rates were significantly lower (35%) than that in non-treated Tet-NI (60%), suggesting inhibition of the parasite's cysteine protease as a possible therapeutic approach.

Original languageEnglish
Pages (from-to)473-480
Number of pages8
JournalJournal of Fish Diseases
Issue number6
StatePublished - 1 Jun 2010


  • Cysteine protease
  • Fish
  • Guppy
  • Infection
  • Tetrahymena
  • Treatment

ASJC Scopus subject areas

  • Aquatic Science
  • Veterinary (miscellaneous)


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