Natural plant cysteine proteinases as anthelmintics?

Infections with gastrointestinal nematodes have severe consequences for the health of millions of people worldwide, and cause serious economic losses in livestock farming. Current control relies heavily on anthelmintic drugs, to which resistance is now developing rapidly. Plant cysteine proteinases, from the fruits or latex of plants such as papaya, pineapple and fig, have high proteolytic activities that are known to digest nematode cuticles, have low toxicity and have been used in traditional medicines against gastrointestinal nematodes for decades. These proteinases constitute strong candidates for a much needed alternative strategy for the treatment of gastrointestinal nematode infections of both humans and animals.