Potential Application of Hibiscus sabdariffa L. (Malvaceae) Aqueous Extract for Assessment of Viability of Protoscolices from Hydatid Cysts

Cystic echinococcosis (hydatidosis) is a serious zoonotic parasitic disease of global public health and economic importance. It is caused by infection with hydatid cysts, the larva of a tapeworm of canines, particularly dogs. The canine hosts become infected with the adult parasite when they ingest with viscera fertile hydatid cysts containing protoscolices (PSCs). Generally, the mere presence of PSCs in a hydatid cyst has been considered an indication of infectivity to the host. There is no tangible measure, however, to assess the degree of this infectivity apart from feeding experimentally to the host (dogs) a known number of PSCs and counting at necropsy the number of adult worms that develop in the intestine. This approach, however, though technically feasible, has several limitations not least among which is the potential error in finding such very small worms in the intestine and the health hazard from exposure to infective eggs released by patent worms. To avoid such risks, a number of commercial stains have been used in in vitro tests to assess the viability of PSCs (defined as the capacity of being alive), a property closely linked to infectivity. Hibiscus sabdariffa is a flowering plant widely cultivated in Sudan. Aqueous extracts from plant calyces have characteristic brilliant red coloration due to the presence of anthocyanins, an important group of water-soluble plant pigments. The present study examines the potential application of aqueous extract of plant calyces for assessment of viability of PSCs taking uptake/exclusion of plant pigment as criteria. It is proposed that the application of extract can be used effectively as an objectively quantifiable low-cost assay for assessment of viability of PSCs from hydatid cysts. Performance of extract is comparable to eosin.