title: Oral dosing with papaya latex is an effective anthelmintic treatment for sheep infected with Haemonchus contortus.
abstract: BACKGROUND
  The cysteine proteinases in papaya latex have been shown to have potent anthelmintic properties in monogastric hosts such as rodents, pigs and humans, but this has not been demonstrated in ruminants.
  
  
  METHODS
  In two experiments, sheep were infected concurrently with 5,000 infective larvae of Haemonchus contortus and 10,000 infective larvae of Trichostrongylus colubriformis and were then treated with the supernatant from a suspension of papaya latex from day 28 to day 32 post-infection. Faecal egg counts were monitored from a week before treatment until the end of the experiment and worm burdens were assessed on day 35 post-infection.
  
  
  RESULTS
  We found that the soluble fraction of papaya latex had a potent in vivo effect on the abomasal nematode H. contortus, but not on the small intestinal nematode T. colubriformis. This effect was dose-dependent and at tolerated levels of gavage with papaya latex (117 μmol of active papaya latex supernatant for 4 days), the H. contortus worm burdens were reduced by 98%. Repeated treatment, daily for 4 days, was more effective than a single dose, but efficacy was not enhanced by concurrent treatment with the antacid cimetidine.
  
  
  CONCLUSIONS
  Our results provide support for the idea that cysteine proteinases derived from papaya latex may be developed into novel anthelmintics for the treatment of lumenal stages of gastro-intestinal nematode infections in sheep, particularly those parasitizing the abomasum.
authors.affiliation: Department of Infection & Immunity, University of Sheffield Medical School, Sheffield, S10 2RX, UK.
authors.forename: David J
authors.initials: DJ
authors.lastname: Buttle
authors.forename: Jerzy M
authors.initials: JM
authors.lastname: Behnke
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Bartley
authors.forename: Hany M
authors.initials: HM
authors.lastname: Elsheikha
authors.forename: David J
authors.initials: DJ
authors.lastname: Bartley
authors.forename: Martin C
authors.initials: MC
authors.lastname: Garnett
authors.forename: Alison A
authors.initials: AA
authors.lastname: Donnan
authors.forename: Frank
authors.initials: F
authors.lastname: Jackson
authors.forename: Ann
authors.initials: A
authors.lastname: Lowe
authors.forename: Ian R
authors.initials: IR
authors.lastname: Duce
mesh_terms: D000818:Animals; D000871:Anthelmintics / Q000008:administration & dosage* / Q000302:isolation & purification; D029441:Carica / Q000737:chemistry*; D005243:Feces / Q000469:parasitology; D006188:Haemonchiasis / Q000188:drug therapy / Q000662:veterinary*; D006189:Haemonchus / Q000302:isolation & purification; D007840:Latex / Q000008:administration & dosage* / Q000302:isolation & purification; D010270:Parasite Egg Count; D012756:Sheep; D012757:Sheep Diseases / Q000188:drug therapy*; D016896:Treatment Outcome; D014253:Trichostrongylosis / Q000188:drug therapy / Q000662:veterinary*; D014254:Trichostrongylus / Q000302:isolation & purification
chemical_list: D000871:Anthelmintics; D007840:Latex