Potential Application of Lawsonia inermis L. (Lythraceae) Aqueous Extract as an Objectively Quantifiable Assay for Assessment of Viability of Protoscolices from Hydatid Cysts

Cystic echinococcosis, also known as hydatidosis, is a serious zoonotic disease. Protoscolices (PSCs) in hydatid cysts are the infective form of the tapeworm Echinococcus granulosus senso lato, an intestinal parasite of canines, particularly dogs. The cysts develop in a wide range of domestic and wild ungulates as intermediate hosts and humans as an aberrant host following incidental ingestion of parasite eggs. Canine hosts acquire infection with the adult parasite when they ingest with viscera fertile hydatid cysts containing PSCs. Problems, however, arise on how to assess the degree of this infectivity in the absence of a tangible method for measuring the success or failure of PSCs to develop inside the canine host. Critical evaluation of infectivity is essential to determine the relative importance of different species of intermediate hosts in parasite transmission and epidemiology of the disease. Several studies described staining with chemical reagents for assessment of viability of PSCs (defined as capacity of being alive), a property closely linked to infectivity. Lawsonia inermis L. (Lythraceae), commonly called “Henna”, is a widely spread plant famous for having dyeing properties due to the presence of lawsone, a red-orange pigment extracted from plant leaves. The objective of this study was to examine the potential application of aqueous extract of plant leaves as a natural product for assessment of viability of PSCs using uptake/exclusion of plant pigment as criteria.