Use of Medicinal Plants Against Parasitic Infections

Abstract

Many of medicinal plants are called "ethnobotanicals" used in traditional homemade remedies that have been used for centuries in various regions. Some of the chemicals in plant extracts are well known and characterized (e.g. azadirachtin, citronella, nicotine, etc.) and can be considered as "natural" active ingredients. Some of these active ingredients have genuine insecticidal or anthelmintic properties (i.e. they actually kill some parasites). They are also known as biopesticides. Many of them act as repellent whereas some of them act as insecticide. Herb mixtures (dried, powdered, pelleted, etc.) are commercially available for preparing infusions or for direct feeding to livestock or pets, with various claims against external or internal parasites. Industrially produced plant extracts (e.g. citronella oil and neem oil) are usually well characterized and standardized (Benavides et al., 2001; Ismail et al., 2002 and John et al. 2009). A common feature of most of these natural products is that they are not persistent. They are easily degradable (e.g. by sunlight) and/or rather volatile, or quickly metabolized and excreted, which are rather positive features regarding safety. For parasiticidal effect treatment has to be repeated frequently for constant protection of animals against parasites. Use of these herbal products against parasitic infections becomes mandatory owing to development of resistance against commonly used chemical anti-parasitic compounds. As the anti-parasitic resistance is the genetic ability of parasites to survive treatment with an anti-parasitic drug that was generally effective against those parasites in the past. After treatment with an anti-parasitic drug, the susceptible parasites die and the resistant parasites survive to pass on resistance genes to their offspring.