In vitro antiprotozoal activity of organic waste materials against Cryptosporidium parvum

Abstract

Plant residues and by-products from pharmaceutical or food production may be cost-efficient sources of functional feed ingredients in animal nutrition. In the course of the EU-funded project SAFEWASTES numerous materials that usually are treated as wastes are evaluated for their potential for further usage. The present study investigated in vitro antiprotozoal effects against Cryptosporidium parvum, an intestinal parasite (Apicomplexa) that infects a wide range of hosts including humans. Especially young or immunocompromised animals are susceptible to infection and mass propagation of the parasite which is often accompanied by loss of weight and water, retarded development and increased susceptibility to other diseases. Among several methods a cell culture assay with HCT-8 host cells was chosen for determination of anti-cryptosporidial effects of test substances. Intracellular parasite development was evaluated microscopically after labelling by indirect fluorescent antibody technique (IFAT). Cell vitality assays were conducted simultaneously to assess eventual deleterious effects on the host cells, since it is important to discriminate unspecific cytotoxic effects from direct effects against the parasites. 53 extracts prepared from 18 different organic waste materials were screened in this assay. An ethanol extract from olive press-cake effectively inhibited C. parvum development while being tolerated by the host cells in the applied concentrations. Monensin as a positive control inhibited parasite development in a highly reproducible way. Bioassay-guided fractionation was done to identify the active principles of the materials.