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BackgroundPlants have traditionally been used for treatment of human and livestock ailments in Ethiopia by different ethnic and social groups. However, this valuable source of knowledge is not adequately documented, which impedes their widespread use, evaluation and validation. Here, we recorded indigenous knowledge and standard practices for human and livestock disease control, of three ethnic groups (Aari, Maale and Bena-Tsemay) in South Omo Zone of Southern Nations, Nationalities and Peoples Regional State, Ethiopia.MethodsA cross-sectional study was carried out using a semi-structured questionnaire to document knowledge of 50 traditional healers (40 male and 10 female) in medicinal plant use for treatment of human and livestock ailments. Descriptive statistics were used to analyze and summarize the ethno-botanical data.ResultsNinety-one plants, with claimed medicinal properties against a total of 34 human and livestock ailments, were reported and botanically identified as belonging to 57 genera and 33 plant families. Most of the plant species reported belonged to one of seven major families: Lamiaceae, Solanaceae, Menispermiaceae, Fabaceae, Asteraceae, Plumbaginaceae and Geraniaceae. Woody plants (shrubs 21% and trees 29%) were the major growth form used, whilst roots (40%) and leaves (35%) were the major plant parts used in the study areas. Healers mostly practice oral administration of plant preparations (65%). Multiple medicinal plants were cited against particular ailments, and mixing of two or more different medicinal plants (14.3%) against a single ailment was also commonly reported.ConclusionThis study showed that traditional medicine, mainly involving the use of medicinal plants, is playing a significant role in meeting the primary healthcare needs of the three ethnic groups. Acceptance of traditional medicine and limited access to modern healthcare facilities could be considered as the main factors for the continuation of the practice. Documented knowledge of the traditional healers can be used to support the country’s human and livestock health care system and improve lives and livelihoods. Information generated will be used in future studies to validate bioactivity of selected medicinal plants used by traditional healers, so to increase their acceptability in health care systems both nationally and internationally.

The use of medicinal plants for the prevention and treatment of gastro-intestinal parasitism has its origin in ethnoveterinary medicine. Although until recently the majority of the evidence on the antiparasitic activity of medicinal plants was anecdotal and lacked scientific validity, there is currently an increasing number of controlled experimental studies that aim to verify and quantify such plant activity. There are indeed a large number of plants whose anthelmintic activity has been demonstrated under controlled experimentation, either through feeding the whole plant or administering plant extracts to parasitised hosts. However, contrary to traditional expectation, there are also a great number of plants with purported antiparasitic properties, which have not been reproduced under experimental conditions. In this paper, we discuss the source of such inconsistencies between ethnoveterinary wisdom and scientific experimentation. We focus on the strengths and weaknesses of the existing methodologies used in the controlled studies to determine the activity of antiparasitic plants. We discuss issues like the seasonal and environmental variability of the plant composition, and how this can affect their antiparasitic properties and highlight the importance of identifying the mechanisms of action of such plants and the target parasite species. In addition to their antiparasitic properties, medicinal plants may also have anti-nutritional properties, which can affect animal performance and behaviour. For this reason, we emphasise the need for considering additional dimensions when evaluating medicinal plants. We also question whether using similar criteria as those used for the evaluation of anthelmintics is the way forward. We propose that a holistic approach is required to evaluate the potential of medicinal plants in parasite control and maximise their benefits on parasitised hosts. Keywords: bioactive plants, ethnoveterinary medicine, medicinal plants, parasites, ruminants IntroductionFor centuries, medicinal plants have been used to combat parasitism, and in many parts of the world are still used for this purpose. In ethnoveterinary medicine, which draws inspiration from traditional practice, there seems to be a range of plant/s or plant extract suitable for treating almost every parasitic disease of livestock (International Institute of Rural Reconstruction (IIRR), 1994). For example, seeds of garlic, onion and mint have been used to treat animals that suffer from gastro-intestinal parasitism, whereas extracts of the tobacco plant have been used to treat the skin of livestock afflicted with external parasites (Guarrera, 1999). Leaves, dried flowers and oil from Chenopodium ambrosioides, a shrub that originated from Central America and has been distributed around the world, have all been used as anthelmintics since the early 1900s (Guarrera, 1999).Reports from around the world include exhaustive lists of plants that have been reported to have medicinal properties (Hammond et al., 1997;Akhtar et al., 2000;Waller ...

The purported antiparasitic properties of plant secondary metabolites (PSM) have been the cause of controversy amongst the scientific community. Despite long-standing knowledge of the prophylactic and therapeutic properties of PSM-rich extracts, which comes mainly from ethnoveterinary sources, the scientific evidence of the antiparasitic effects of PSM is inconsistent. In the first part of the present paper the causes of this controversy are addressed, and the evidence available on the antiparasitic effects of PSM is critically examined. The focus is on examples of the antiparasitic activity of PSM against helminth nematodes. The conclusion is that PSM can have antiparasitic properties, which depend on their structure, level of ingestion and availability within the gastrointestinal tract of the animal. The second part is an appraisal of the potential role of PSM for parasite control in ruminant production systems. Despite their antiparasitic properties, PSM consumption does not necessarily have positive consequences in parasitised herbivores, as excessive consumption of PSM can adversely affect herbivore fitness and survival, through their anti-nutritional properties. For this reason it is suggested that the antiparasitic properties of PSM should be assessed at the same time as their anti-nutritional effects. The same measure, e.g. the performance of parasitised hosts, should be used when assessing these properties. The assessment of the costs and benefits suggests that parasitised herbivores can benefit from the long-term consumption of PSM only if the antiparasitic benefits outweigh the anti-nutritional costs of PSM. In addition, it is proposed that parasitised animals might be able to benefit from PSM consumption even if their performance is impaired, as long as the latter is a short-term compromise that leads to long-term benefits.

Host-parasite interactions are often seen as an arms race, with parasites attempting to overcome host resistance to infection. Herbivory is a common route of transmission of parasites that represents the most pervasive challenge to mammalian growth and reproduction. The present paper reviews the foraging skills of mammalian herbivores in relation to their ability to exploit plant properties to combat parasites. The starting point is that foraging behaviour may ameliorate the impact of parasitism in three ways; hosts could: (1) avoid foraging in areas contaminated with parasites; (2) select diets which increase their resistance to parasites; (3) select for foods containing anti-parasitic properties (self-medication). Details are given of the pre-requisite skills needed by herbivores if they are to combat parasitism via behaviour, i.e. herbivores are able to: (a) determine their parasitic state and alter their behaviour in relation to that state (behaviours 1, 2 and 3); (b) determine the environmental distribution of parasites (behaviour 1); (c) distinguish plant species or plant parts that increase their resistance to parasites (behaviour 2) or have anti-parasitic properties (behaviour 3). Mammalian herbivores cannot detect the presence of the parasites themselves and must rely on cues such as faeces. Despite the use of these cues contacting parasites may be inevitable and so mechanisms to combat parasitism are necessary. Mammalian herbivores have the foraging skills needed to exploit the heterogeneous distributions of nutrients and parasites in complex foraging environments in order to avoid, and increase their resistance to, parasites. Current evidence for the use of plant secondary metabolites (PSM) by herbivores for self-medication purposes remains equivocal. PSM have both positive (anti-parasitic) and negative (toxic) effects on herbivores. Here details are given of an experimental approach using tri-trophic (plant-herbivore-parasite) interactions that could be used to demonstrate self-medication in animals. There is strong evidence suggesting that herbivore hosts have developed the foraging skills needed to take advantage of plant properties to combat parasites and thus use behaviour as a weapon in the host-parasite arms race.

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