Abstract
Conventional drugs have become expensive and therefore unaffordable to resource-limited farmers, causing farmers to seek low cost alternatives, such as use of medicinal plants. In this study, a survey was conducted in order to document information on medicinal plants used by farmers in the control of internal parasites in goats in the Eastern Cape Province. Structured questionnaires and general conversation were used to collect the information from farmers and herbalists. The survey revealed 28 plant species from 20 families that are commonly used in the treatment of gastro-intestinal parasites in goats. The plant family Asphodelaceae was frequent in usage, comprising 21.4% of the plants, and the Aloe was the most utilized species (50%). Leaves were the most frequently used plant parts (45.9%), and decoctions constituted the majority of medicinal preparations (70%). Medicinal plants are generally used in combination with other plants, and/or non-plant substances, but a few plants are used on their own. These medicinal plant remedies are administered orally, mainly by use of bottles and this is done twice in summer at intervals of one month, only once in winter and when need arises thereafter. Some of the mentioned plants have been reported in literature to possess anthelmintic properties, while others possess activities ranging from anti-inflammatory, analgesic, antimicrobial, purgative, anti-edema to immuno-regulation. If their safety and efficacy could be confirmed, these plants could form an alternative cost effective strategy in managing helminthiasis in the province.
Introduction
Helminthiasis is one of the most important animal diseases worldwide, causing heavy production losses in grazing animals (CitationAkhtar et al., 2000). It is prevalent in developing countries, mainly due to warm temperatures, in association with poor management practices and inadequate control measures (CitationAkhtar et al., 2000). This disease is caused by a range of internal parasites including roundworms, tapeworms, lungworms and flukes (CitationPerry et al., 2002). Pharmacotherapy is one of the most important means of controlling helminthiasis, but it is possible only if livestock farmers can afford the high cost of drugs (CitationSori, et al., 2004). Unfortunately, resource-limited farmers in the Eastern Cape have low incomes (CitationMasika & Afolayan, 2003), making affordability and accessibility of the conventional drugs difficult.
Besides, problems have emerged with the use of anthelmintics world-wide, notably the development of drug resistant helminths, as well as chemical residue in animal products (CitationWalter & Prichard, 1985). Furthermore, parasites resistant to many anthelmintic drugs have been reported in small ruminants (CitationAxford et al., 2000), leading to a resurgence of interest in the use of herbal medicines to control and treat diseases and parasites in small ruminant animals. There is also a general belief that natural products are safer and more harmonious with biological systems (CitationAtal, 1983; CitationErasto, 2003).
Livestock farmers in the Eastern Cape of South Africa have a long history of using plants to treat animal ailments (CitationDold & Cocks, 2001). This ethnoveterinary practice is an integral part of South African culture, a position that is unlikely to change to any significant degree in the coming years (CitationMasika & Afolayan, 2003). It has been estimated that close to 75% of resource-limited livestock farmers in the Eastern Cape Province use traditional medicine to treat their animals (CitationMasika et al., 2000) and it is believed that most of these plants possess pharmacologically active compounds (CitationCoetzee, 2000). Generally, medicinal plants are cheaper to use, are accessible and acceptable in the communities.
Ethnoveterinary information is usually passed from older generation to the apprentices by oral tradition (CitationHutchings, 1989; CitationVan Wyk et al., 2002). However, there is a danger that some of the knowledge may be distorted or completely lost during transfer, leading to loss of the information with time. There is, therefore, an urgent need to document plants used in ethnoveterinary practices, so that knowledge can be preserved, plants conserved and sustainably managed. This paper presents information on medicinal plants used by resource-limited farmers to control worms of goats in the Eastern Cape Province of South Africa.
Materials and methods
The study area
The study was carried out in the Eastern Cape Province of South Africa, which falls within the latitudes 30° 00′–34° 15′ S and longitudes 22° 45′–30° 15′ E. It is bounded by the sea in the east and the drier Karoo (semi-arid vegetation) in the west. The elevation ranges from sea level to approximately 2,200 m in the north, and the vegetation is veld type number 7, known as the Eastern Cape thorn veld (CitationAcocks, 1975). This area consists of many villages which are generally classified as rural and poor (CitationErasto et al., 2005).
Collection of information
Information was collected from three districts that were selected based on annual rainfall received in the regions. These were Alice (> 1000 mm), Stutterheim (700-800 mm), and Middledrift (<600 mm). Three villages from each district were then selected, Khayalethu, Trust, Auckland (Alice), Frankfort, Gubevu, Peelton (Stutterheim) and Koloni, Pewuleni, Qibira (Middledrift). Adopting the method of CitationJovel et al. (1996), general conversation and questionnaires were used to obtain information on plants used to treat helminthiasis in goats. The information was obtained from a total of 30 adults with ages ranging from 40 to 60 years and of these, 16 were herbalists and 14 were goat farmers. Selection of respondents was done using the snow ball sampling method, based on knowledge of medicinal plant use. According to CitationPatton (1990), snowball sampling is an approach for locating information-rich key informants, who are then contacted and interviewed, following which they in-turn direct the interviewer to other potential respondents. Following the interviews, plant samples were collected by Mrs Brink, pressed and identified by their vernacular names. The local names were later matched with the scientific ones at the Albany Museum Herbarium in Grahamstown. Voucher specimens were also prepared and deposited at the University of Fort Hare Herbarium, specimen number VMAP01-028/2006. The study protocol was approved by Govan Mbeki Research and Development Centre in accordance with the University of Fort Hare Research and Ethical Policy, and the collection of the plant materials was done under the guidance of one of the community leaders to ensure that the biodiversity rights of the indigenous people were protected.
Results and discussion
Overall, 28 plant species, belonging to 20 families used by resource-limited farmers in the control of gastro-intestinal parasites in goats were recorded (). The most frequently mentioned family was Asphodelaceae representing 21.4% of all the plant species; this could be due to its vast natural distribution, with 13 genera (CitationTreutlein et al., 2003). Aloe arborescens Mill, Aloe ferox Mill, Bulbine latifolia L.F., Bulbine frutescens L.Willd., Bulbine abyssinica A. Rich, and Gasteria bicolor Haw were the plant species mentioned in this family. Among these, Aloe species was the most frequently used (50%). This may be due to the general broad spectrum medicinal uses of the Aloe species (CitationVan Wyk et al., 2002).
Table 1. Medicinal plants used as anthelmintics in goats.
Different plant parts are generally used in the formulation of remedies. In this study leaves were the most frequently mentioned, constituting about 46% of the herbal preparations (). This is similar to findings by CitationMasika and Afolayan (2003), who also reported the highest percentage in the use of leaves in herbal preparations. Use of leaves has a conservational advantage, compared to use of whole plants, roots and tubers, which are destructive and not sustainable. In this survey, 26% of the respondents used tree bark, 19% used roots and tubers, and only 10% used whole plant in herbal preparations.
For their medicinal preparations, 71% of the respondents use decoctions and 29% use infusions. This is in consonance with CitationMasika and Afolayan (2003), who reported 78% use of decoctions. Decoction involves heating plant material in water to boiling point whereas infusion involves soaking in water at ambient temperature overnight. In both preparations plant materials were pulverized before boiling or soaking in water. Boiling of plant materials extracts water soluble (polar) compounds, it could also degrade or modify actives and could also result in detoxification of some poisonous plants, depending on the toxins involved.
In the majority (87%) of cases, treatment was administered using a 750 mL bottle and 13% used either a cup or syringe, for medications ranging from 20 to 750 mL. Treatment for worms is done twice in summer at intervals of one month, only once in winter and whenever the need arises thereafter. Helminthiasis is more prevalent in summer when it is warm, humid and the grass is green, which are conditions that are favorable for worm survival, compared to winter when it is cold and dry. This treatment regime almost parallels the conventional approaches used in the control of worms, which could be an indication that the farmers in this study are guided by their knowledge of conventional practices of controlling worms.
The study also revealed that 47% of the respondents combine more than one plant in the preparation of medicines. Plant combinations may have a synergistic effect, and could result in more effective treatment of a wider range of worms and their effects. Some (33%) of the respondents mixed plant extracts with non-plant materials such as potassium permanganate, copper sulfate, Epsom salts and table salt, and blue soap. Potassium permanganate, copper sulfate and salt are reported in literature to have been used in fish aquariums to control fish worms (CitationHemaprasanth et al., 2006). Epsom salts are reported to have a laxative effect, whereas soap may increase the biological activity because of drug distribution between soap micelles. However, some plants, Zanthoxylum capense, Thunb. (Rutaceae) Aloe ferox, Teucrium trifidum, Retz. (Lamiaceae) and Capparis seiaria L. (Capparidaceae) were used without combinations. Farmers did not provide information on individual plants or their combinations used for specific worm types. However, in two cases mention was made of finding dead tapeworms expelled after dosing with A. arborescens, and in one case dead wireworms were found expelled after dosing with a combination of Hermannia incana, A. vera, and table salt. Two of the plants used, Acokanthera oppositifolia Lam. (Apocynaceae) and Strychnos henningsii Gilg. (Loganiaceae) are known to be highly toxic due to the presence of acovenoside A, and strychnine and henningsiine, respectively (CitationVan Wyk et al., 2002). Farmers and herbalists in the Eastern Cape are, however, aware of the poisonous nature of these plants. They therefore mix small amounts of A. oppositifolia with Harpephyllum caffrum Bernh. (Anacardiaceae) and Teucrium trifidum Retz (Lamiaceae), which contains flavonoids and diterpenoids, respectively, and make decoctions. In addition to small quantities of these toxic plants in the in the herbal preparations, more water is also added and the mixture is boiled. Synergism is known to result in reduced toxicity (CitationCalabrese, 1995); administration of plant extracts from these plants mixed with other plants may therefore reduce their toxic potential. Boiling may also result in detoxification of plant extract especially with respect to some aromatic poisonous compounds which may evaporate. Use of large quantities of water during boiling may also reduce toxicity of the plants by making the more dilute rather than concentrated mixtures. It is also possible that small quantities of S henningsii and A. oppositifolia in the mixtures may reduce their toxicity potential. CitationPangborn (1994) has also documented some natural detoxification processes in the body which primarily target heavy metals, chemical toxins and microbial compounds. These result in burying the toxic compounds in body fat, excreting them, changing them to a less toxic form and storing or changing them to a suitable form for elimination.
According to literature, some of the plants that are used by the resource-limited farmers against internal parasites have been reported to possess various pharmacologically active substances. Aloe ferox and Rumex lanceolatus (L) R.Br. (Polygonaceae) have been reported to be used in the treatment of helminthiasis (CitationMasika & Afolayan 2003). Anthelmintic activities of Zanthoxylum capense have been reported by CitationMcGaw et al., (2000) and is also being used as a parasiticide (CitationHutchings et al., 1996), while Acokanthera oppositifolia is being used to treat tapeworms (CitationVan Wyk et al., 2002) Aloe ferox, has been reported to have a laxative effect, due to the aloin content, and has also been used in the treatment of gall sickness and heartwater (CitationVan Wyk et al., 2002; CitationMasika & Afolayan, 2003). Strychnos henningsii Gilg. (Loganiaceae) has been reported to have purgative, and muscle relaxing effects (CitationVan Wyk, et al., 2002). The roots of R. lanceolatus have been reported to contain glycosides of chrysophanol, and Zanthoxylum capense is said to possess some alkaloids, which also have anti-inflammatory and anti-plague effects (CitationVan Wyk et al., 2002).
Capparis sepiaria L. (Capparidaceae), Centella coriacea Nannf. (Apiaceae), Pittosporum viridiflorum Sims (Pittosporaceae), Agapanthus praecox Willd. (Agapanthaceae), and Harpephyllum caffrum are reported to have anti-inflammatory effects (CitationVan Wyk et al., 2002). A. praecox, C. sepiaria, and P. viridiflorum are reported to contain saponins, which also possess analgesic, antibiotic, anti-edema, laxative and immunoregulatory effects. Harpephyllum caffrum contains flavonoids, which also possess antioxidant properties, whereas C. coriacea contains triterpenoids, which also have purgative and antibiotic effects. Schotia latifolia Jacq. (Fabaceae), Grewia occidentalis L.F., Elephantorrhiza elephantina (Burch.) Skeels (Fabaceae), Leonotis leonurus (L.) R.Br. (Laminaceae) and Bulbine species have been reported to possess antibiotic properties (CitationMasika & Afolayan, 2003; CitationVan Wyk et al., 2002; CitationVan Wyk & Wink, 2004). This is due to the presence of stilbenes and diterpenoids in S. latifolia, and L. leonurus, respectively, as well as tannins suspected to be contained in E. elephantina due to its bright red color (CitationVan Wyk et al., 2002). Diterpenoids have also been reported to have anti-inflammatory effects (CitationVan Wyk et al., 2002).
Gastrointestinal parasites manifest symptoms based on pathological changes in various animal organs. For example, response to gastrointestinal parasites challenge results in host inflammatory reactions against localized parasite products in the gastrointestinal tract (CitationMeeusen, 1999). Most plants used by the farmers are reported to possess activities ranging from anti-inflammatory, analgesic, antimicrobial, purgative, anti-edema to immunoregulation. Their use could therefore be effective in symptomatic treatment of helminthiasis, as well as boosting the immune system of the animals. This shows that alleviation of clinical signs is also targeted in the treatment regime. Purgative effects will lead to enhanced gastric and intestinal emptying which is desirable in the treatment of worm infestation. Indeed, most of the effective anthelmintics currently in use also have purgative components for worm expulsion (CitationChidume et al., 2002).
This study has revealed the potential role some of the medicinal plants found in the Eastern Cape can play in the treatment of internal parasites in goats. These plants could form an alternative cost effective strategy in managing helminthiasis in the province, especially if their efficacy could be confirmed. Work is in progress to validate the efficacy and safety, as well as the pharmacological properties of some of the plants mentioned in this study.
Acknowledgements
The authors would like to thank Mrs. E. Brink of Albany Museum in Grahamstown for technical support in the identification of plant specimen, and Mr. S. Boltina for the assistance he rendered during the fieldwork. We are also grateful to all the people in the communities of the Eastern Cape Province who shared their valuable information with us during the surveys.
Declaration of interest
The authors acknowledge Govan Mbeki Research and Development Centre at the University of Fort Hare for financial support.
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