Oral dosing with papaya latex is an effective anthelmintic treatment for sheep infected with Haemonchus contortus

David J Buttle,Martin C Garnett,Jerzy M Behnke,Frank Jackson,David J Bartley,Alison A Donnan,Ian R Duce,Hany M Elsheikha,Yvonne Bartley,Ann Lowe

doi:10.1186/1756-3305-4-36

Abstract

BackgroundThe 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.MethodsIn 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.ResultsWe 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.ConclusionsOur 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.

Highlights

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
Experiment 1 - Dose-response effects of papaya latex supernatant on H. contortus and T. colubriformis In the control group treated with water, mean undifferentiated faecal egg counts (FEC) values (Figure 1) were fairly steady throughout the period of observation, with arithmetic means varying from 6349 (±1182; standard error of the mean) on day 21 p.i. to 12010 (±2247) on day 35 p.i. with a peak count of 14143 (±2875) on day 31 p.i
In relation to day 28, just prior to treatment, and based on arithmetic means, FEC rose in the control group on day 35 by 12.0%, fell in Group 2 (47 μmol of papaya latex supernatant (PLS)) by 66.4%

Summary

Introduction

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. Natural plant-derived products have been known for many decades to possess anthelmintic properties [5,6] and yet generally these have been inadequately researched and none have been taken to the market stage. One such group of potential anthelmintics is the cysteine proteinases found in fruits such as papaya, figs, kiwi fruits and pineapples. Fig and papaya extracts have been shown to reduce intestinal helminth infections in humans and in other monogastric animals including pigs [12,13]

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Conclusion