The search for new deworming agents in the face of growing chemical resistance has researchers looking to the supermarket produce aisle: A preliminary study from England suggests that fruits such as pineapple, papaya and figs may be useful in controlling internal parasites in horses.

Building on the knowledge that enzymes in these fruits called cysteine proteinases can digest adult worms, researchers at the University of Liverpool exposed parasites at various stages of development to papaya extract. They discovered that—in a laboratory setting, at least—exposure to the extract inhibited the hatching of parasite eggs and the movement of infective larval stages in small red worms (cyathostomins).

The researchers note that while the inhibited hatching appeared directly related to cysteine proteinases, the inhibition of larval stages may be the function of a secondary compound present in the extract.

They call for further studies to evaluate the efficacy of these fruits and their enzymes against various stages of parasite development, in both the laboratory and a real-world setting.

Reference: “Papaya latex supernatant has a potent effect on the free-living stages of equid cyathostomins in vitro,” Veterinary Parasitology, September 2016