Ethnobotanical study of medicinal plants used by people in Zegie Peninsula, Northwestern Ethiopia

An ethnobotanical study was conducted from October 2005 to June 2006 to investigate the uses of medicinal plants by people in Zegie Peninsula, northwestern Ethiopia. Information was gathered from 200 people: 70 female and 130 males, using semistructured questionnaire. Of which, six were male local healers. The informants, except the healers, were selected randomly and no appointment was made prior to the visits. Informant consensus factor (ICF) for category of aliments and the fidelity level (FL) of the medicinal plants were determined. Sixty-seven medicinal plants used as a cure for 52 aliments were documented. They are distributed across 42 families and 64 genera. The most frequently utilized plant part was the underground part (root/rhizome/bulb) (42%). The largest number of remedies was used to treat gastrointestinal disorder and parasites infections (22.8%) followed by external injuries and parasites infections (22.1%). The administration routes are oral (51.4%), external (38.6%), nasal (7.9%), and ear (2.1%). The medicinal plants that were presumed to be effective in treating a certain category of disease, such as 'mich' and febrile diseases (0.80) had higher ICF values. This probably indicates a high incidence of these types of diseases in the region, possibly due to the poor socio-economic and sanitary conditions of this people. The medicinal plants that are widely used by the local people or used as a remedy for a specific aliment have higher FL values (Carissa spinarum, Clausena anisata, Acokanthera schimperi, Calpurnia aurea, Ficus thonningii, and Cyphostemma junceum) than those that are less popular or used to treat more than one type of aliments (Plumbago zeylanicum, Dorstenia barnimiana).


Background
Ethnobotanical studies are often significant in revealing locally important plant species especially for the discovery of crude drugs. Right from its beginning, the documentation of traditional knowledge, especially on the medicinal uses of plants, has provided many important drugs of modern day [1,2]. Traditional medicine still remains the main resource for a large majority (80%) of the people in Ethiopia for treating health problems and a traditional medical consultancy including the consumption of the medicinal plants has a much lower cost than modern medical attention [3][4][5].
Out of the total flowering plants reported from the world, more than 50,000 are used for medicinal purposes [6,7]. In Ethiopia, about 800 species of plants are used in the traditional health care system to treat nearly 300 mental and physical disorders. The wide spread use of traditional medicine among both urban and rural population in Ethiopia could be attributed to cultural acceptability, efficacy against certain type of diseases, physical accessibility and economic affordability as compared to modern medicine. Ethiopian traditional medical system is characterized by variation and is shaped by the ecological diversities of the country, socio-cultural background of the different ethnic groups as well as historical developments, which are related to migration, introduction of foreign culture and religion. Previous studies showed the existence of traditional medical pluralism in the country. In Ethiopia, either the knowledge from herbalists is passed secretively from one generation to the next through words of mouths or their descendants inherit the medico-spiritual manuscripts [8][9][10][11][12].
The study of Ethiopian medicinal plants has not been realized as fully as that of India or other traditional communities elsewhere [13]. In Ethiopia, though there has been some organized ethnomedicinal studies, there is limited development of therapeutic products and the indigenous knowledge on usage of medicinal plants as folk remedies are getting lost owing to migration from rural to urban areas, industrialization, rapid loss of natural habitats and changes in life style. In addition, there is a lack of ethnobotanical survey carried out in most parts of the country. In view of these, documentation of the traditional uses of medicinal plants is an urgent matter and important to preserve the knowledge. Furthermore, most of the ethnomedicinal studies in northern part of Ethiopia are focused on 'Medihanit Awakie' (professional traditional practitioners) and the ancient medico-magical and/or medico-spiritual manuscripts and old Gee'z manuscripts [11,14,15], and ignore the knowledge of ordinary people in the locality [16]. Thus, the purpose of this study is to investigate the traditional uses of medicinal plants by the ordinary people in Zegie Peninsula and to provide baseline data for future pharmacological and phytochemical studies.

Description of the Study Area
Zegie Peninsula (11° 43' N, 37° 20' E) is located at 600 km northwest of Addis Ababa in the country's northwest highlands, at an altitude of approximately 1800 meters. It is partly surrounded by Lake Tana, which is the largest lake in Ethiopia and the source of the Blue Nile. Zegie Peninsula is about three hours motorboat drive or 37 km on land from Bahir Dar, the capital city of Amahra Regional State (Fig. 1). The residents are Amahra people and speak the country's official language Amharic. Tankwas (papyrus boats) of ancient design, manufactured on the shores of Lake Tana, are the alternative forms of transport for the local people between Zegie and Bahir Dar. There are seven monasteries on the peninsula from the 16th and 17th century. Ura Kidane Mhret, one of the monasteries, houses myriads of treasures, beautiful mural paintings, icons, scrolls and thousand-year-old manu-scriptsas well as crowns and dresses from Ethiopian Emperors. During the study time, there were no modern health facilities in the area. The main occupation of the people is fishing, and coffee plantation. Until recently, there was no farming practice because the monasteries in the peninsula had forbidden the use of any type of draft animal for farming. Nevertheless, currently, the people have started farming and clearing the forest for agricultural purposes and this may affect the natural habitats of some of the medicinal plants.

Survey on the Use of Medicinal Plants
The ethnobotanical surveys were carried out from October 2005 to June 2006 using semistructured questionnaire [17] and interview was conducted in Amharic. Prior to the administration of the questionnaire, conversations with the informants were held with the assistance of local Farmers' Association representative to elaborate the objective of the study and to build on trust with the common goal to document and preserve the knowledge on medicinal plants. Two hundred informants were interviewed out of about 2855 inhabitants (1,338 females and 1517 males) of the Zegie peninsula (unpublished data, Bahir Dar Zuria Woreda Administration), these included 130 males and 70 females. Of which, six were male local healers (the only ones found on the peninsula). The female informants' age ranges from 30 to 85 years and the mean age is 51 years, and the male informants' age ranges from 30 to 93 years and the mean age is 64 years. The informants, except the healers, were selected randomly and no appointment was made prior to the visits. They were asked to give their knowledge about the plants they use against a disease, plant parts harvested, method of preparation of the remedy, details of administration and the dosage. Specimens of the reported medicinal plants were collected during regular systematic walk in the fields and identified by specialists at the Aklilu Lemma Institute of Pathobiology and the National Herbarium of Addis Ababa University following the Flora of Ethiopia and Eritrea [18][19][20][21]. Voucher specimens were deposited at the Herbarium of Aklilu Lemma Institute of Pathobiology, Addis Ababa University.

Data Analysis
The reported aliments were grouped into 10 categories based on the information gathered from the interviewees. The categories were: evil eye and 'satan beshita' (devil sickness), external injuries and parasites infections, gastrointestinal disorder and parasites infections, 'mich' (febrile disease characterized by fever, headache, sweating, Herpes labialis, and muscle spasm) and febrile diseases, rabies and internal disease, respiratory and throat infections, sensorial disease, snake bite, swelling (non-infectious or infectious swelling) and cancer, and venereal disease and impotence. Informant consensus factor (ICF) was calcu-lated for each category of aliments to identify the agreements of the informants on the reported cures for the group of aliments. ICF was calculated as follows: number of use citations in each category (n ur ) minus the number of species used (n t ), divided by the number of use citations in each category minus one [22].
The fidelity level (FL), the percentage of informants claiming the use of a certain plant for the same major purpose, was calculated for the most frequently reported diseases or ailments as: Where Np is the number of informants that claim a use of a plant species to treat a particular disease, and N is the number of informants that use the plants as a medicine to treat any given disease [23]. These two methods are helpful in the selection of plants for further studies.

Knowledge of Informants and Medicinal Plants
Eighty two percent of informants reported remedies for 52 aliments. Of which 26% are females and 74% are males, ICF n n n ur t Map of Zegie Peninsula in Ethiopia Figure 1 Map of Zegie Peninsula in Ethiopia.
which indicated that most people continue to use traditional systems of health care including medicinal plants alone or in combination with modern pharmaceuticals. This continued reliance of many African people on traditional medicines is partly due to economic circumstances, which place modern health facilities, services and pharmaceuticals out of the reach of the majority of the population. However, in many cases, it is also attributable to the widespread belief in the effectiveness of many traditional therapies. Even where western biomedical care is available, many people still prefer traditional treatments for treating many aliments [4,5,11,24].
The females reported remedies to diseases associated to children such as 'mich', stomachache, 'kuruba' (diarrhea, dysentery, stomach disorder), dysentery, tonsillitis and babies' sickness (thinning, loss of appetite). The males reported (mean = 6.7 ± 2.79) more number of remedies than the females (mean = 2.3 ± 0.9) and there is a significant difference (p = 0.004) between female and male and agrees with the previous reports of ethnobotanical studies in northern and southern Ethiopia [4,5]. This is because the traditional knowledge in the family or community is passed from male parent to his first-born son [25,26].
All the healers were male and the number of aliments reported by them ranged from six to twenty. They also reported combination of multiple medicinal plants to treat an illness, whereas most of the non-healers, both females and males reported only a single medicinal plant treatment (Table 1, 2). The multiple prescriptions reported by the healers usually contain a range of pharmacologically active compounds; in some cases, it is not known which ingredients are important for the therapeutic effect and some are used as adjuvants [27].
The number of ethnomedicinally important plant species documented in Zegie Peninsula was 67. These species belong to 64 genera and 44 families. The genera Asteraceae, Euphorbiaceae, Fabaceae and Solanaceae were families with four species each followed by Malvaceae with three species and, Apocynaceae, Asclepiadaceae, Cucurbitaceae, Dracaenaceae, Moraceae, Rhamnaceae and Rutaceae, each contributing two species.
The most frequently utilized plant part was the underground part (root/rhizome/bulb = 42%) ( Table 4). In studies conducted in Ethiopia, root (58.3%) is one of the most extensively used plant part in preparation of traditional herbal medicine [11]. In this study, herbs are used predominantly (52%, Fig. 2) as in most part of Ethiopia (34.8%) [27,28].
The largest number of remedies was used to treat gastrointestinal disorder and parasites (22.8%) followed by exter-nal injuries and parasites (22.1%), rabies and internal diseases (17.9%). The proportion of remedies used for treatment of gastrointestinal related disease are also high in most studies conducted in Ethiopia, accounting for 35% compared to other type of remedies that were compiled as being used against human aliments [28]. The rest were used to treat swelling and cancer (8.3%), evil eye and devil sickness (6.2%), sensorial disease (6.2%), venereal disease and impotence (4.8%), 'mich' and febrile diseases (4.1%), respiratory and throat infection (4.1%), and snake bite (3.4%). Multiple plants treatments with different combinations of medicinal plants were used to treat seven external and internal illnesses. Seventy eight percent of the multiple plants treatments were roots and were prepared by mixing the ingredients with different proportions. Three were used to treat evil eye and one of the polyherbal remedy had nine medicinal plants (Table 3).

Route and dosage of administration
The administration routes are oral (51.4%), external (38.6%), nasal (7.9%), and through the ear (2.1%). The remedies are taken with water, skimmed milk, honey, tef injera (local thin bread made from tef, Eragrostis tef) and boiled coffee. The measurements used to determine the dosages are not standardized and depend on the age and physical appearance of the patient, sociocultural explanation of the illness, diagnosis and experience of individual herbalist [5,11]. Children are given less than adults, such as, one fourth of a coffee cup (2 ml to 5 ml), whereas, an adult is given up to one glass (approximately 250 ml) depending on the type of illness and treatment. The quantity of plant part used is measured by number of leaves, seeds and fruits, and length of root. For example, seven young leaves of Justicia schimperiana are used to treat ascaris, seven seeds of Calpurnia aurea are used to treat diarrhea and about 2 cm of root of Dorstenia barnimiana is used to treat cancer. The frequency of treatment depends on the type of illness and severity. In preparation of polyherbal medicines, each medicinal plant is dried, powdered and stored separately, and the amount taken from each for any given disease varies.

Veterinary Important Traditional Medicines
Eight species of medicinal plants have veterinary importance. The plant parts used were leaf (62.5%) and root (37.5%). These are used as remedy for seven internal and external illnesses ( Table 3). The number of veterinary important medicinal plants is low compared to those areas with culture of cattle raring. Giday and Ameni [29] documented 83 medicinal plants that are used to treat 37 types of livestock aliments. In our study area, people are not accustomed to cattle raring and, therefore, have low knowledge of veterinary important medicinal plants. Leaf powder mixed with water is taken orally rabies Root paste is taken with tef kita in the morning for seven days

Informants consensus and Species Use Value
The medicinal plants that are presumed to be effective in treating a certain disease have higher ICF values. Table 5 shows disease categories with relatively higher ICF values: 'mich' and febrile diseases (0.80), evil eye and satan beshita (devil sickness) (0.70), and respiratory and throat infections (0.64). This may indicate high incidence of these types of diseases in the region, possibly due to the poor socio-economic and sanitary conditions of the people. The categories of diseases that are only treated by the healers and those that are rare have lower ICF values. These include swelling and cancer (38), and sensorial disease (0.25). The medicinal plants that are widely used by the local people have higher FL values than those that are less popular. On the other hand, medicinal plants that are known as remedies of a single aliment have 100% fidelity level than those that are used as remedies for more than one type of aliment. For example, Plumbago zeylanicum is used to treat cancer, respiratory infection, swelling, and rheumatic pain and its FL value is 40% ( Table 6).

Declaration of competing interests
The author(s) declare that they have no competing interests.