Medicinal Plant Use in Africa

The role of traditional medical practitioners

Photo 1. Trainee diviner (twasa) with a small quantity of Boophane disticha (Amarylldaceae) bulbs for local use.

In contrast with western medicine, which is technically and analytically based, traditional African medicine takes a holistic approach: good health, disease, success or misfortune are not seen as chance occurrences but are believed to arise from the actions of individuals and ancestral spirits according to the balance or imbalance between the individual and the social environment (Anyinam, 1987; Hedberg et al., 1982; Ngubane, 1987; Staugard, 1985; WHO, 1977). Traditionally, rural African communities have relied upon the spiritual and practical skills of the TMPs (traditional medicinal practitioners), whose botanical knowledge of plant species and their ecology and scarcity are invaluable. Throughout Africa, the gathering of medicinal plants was traditionally restricted to TMPs or to their trainees (Photo 1). Knowledge of many species was limited to this group through spiritual calling, ritual, religious controls and, in southern Africa, the use of alternative (hlonipha) names not known to outsiders.

Hedberg et al., (1982) observed that the number of traditional practitioners in Tanzania was estimated to be 30 000 - 40 000 in comparison with 600 medical doctors (Table 1) (MP and TMP : total population ratios were not given). Similarly, in Malawi, there were an estimated 17 000 TMPs and only 35 medical doctors in practice in the country (Anon., 1987).

Economic and demographic projections for most African countries offer little grounds for optimism. A shift from using traditional medicines to consulting medical doctors, even if they are available, only occurs with socio-economic and cultural change, access to formal education (Kaplan, 1976) and religious influences (e.g. through the African Zionist movements, which forbid the use of traditional medicines by their followers, substituting the use of ash and holy water instead; Sundkier, 1961). Access to western biomedicine, adequate education and employment opportunities requires economic growth. Unfortunately, most African countries are affected by unprecedented economic deterioration. Per capita income has reportedly fallen by 4% since 1986, whilst Africa’s foreign debt is three times greater than its export earnings. In Zambia, government spending on education has fallen by 62% in the last decade, and that on essential pharmaceutical drugs by 75% from 1985 to 1989 (Zimbabwe Science News, 1989). At the same time, the African population has grown by 3% per annum, increasing the difficulty of adequate provision of Western-type health services. For this reason, there is a need to involve TMPs in national healthcare systems through training and evaluation of effective remedies, as they are a large and influential group in primary healthcare (Akerele, 1987; Anyinam, 1987; Good, 1987). Sustainable use of the major resource base of TMPs - medicinal plants - is therefore essential.

Customary controls on medicinal plant gathering

The sustainable use of medicinal plants was facilitated in the past by several inadvertent or indirect controls and some intentional management practices.

Figure 1. Assessment of debarking damage to Cassine papillosa (Celastraceae) trees in an area where subsistence harvesting rather than commercial exploitation is taking place (Cunningham, 1988a)

Taboos, seasonal and social restrictions on gathering medicinal plants, and the nature of plant gathering equipment all served to limit medicinal plant harvesting. In southern Africa (and probably elsewhere) before metal machetes and axes were widely available, plants were collected with a pointed wooden digging stick or small axe, which tended to limit the quantity of bark or roots gathered. For example, traditional subsistence harvesting of Cassine papillosa bark causes relatively little damage to the tree (Figure 1).

Pressure on medicinal plant resources has remained low in remote areas and in countries such as Mozambique and Zambia where the commercial trade in traditional medicines has only developed to a limited extent due to the small size of major urban centres. Examples of factors which have limited pressure on species which would otherwise be vulnerable to over-exploitation include:

(1) Taboos against the collection of medicinal plants by menstruating women in South Africa and Swaziland; it is believed that this would reduce the healing power of the plants (Scudder and Conelly, 1985).

(2) The tendency in southern Africa for women to practise as diviners, while men practise as herbalists (Berglund, 1976; Staugard, 1985). This limits the number of resource users.

(3) The perceived toxicity of some medicinal species which reduced their use in the past: the level of toxicity is sometimes given mythical proportions. Synadenium cupulare for example, is considered so toxic that birds flying over the tree are killed; special ritual preparations are made in west Africa before the bark of Okoubaka aubrevillei is removed (Good, 1987).

(4) The traditional use of a wooden batten for removal of bark from Okoubaka aubrevillei - under no circumstances may a machete or other metal implement be used (Good, 1987).

For any society to institute intentional resource management controls, certain conditions have to be fulfilled:

(1) the resource must be of value to the society;

(2) the resource must be perceived to be in short supply and vulnerable to over-exploitation by people;

(3) the socio-political nature of the society must include the necessary structures for resource management.

Intentional resource management controls have endured in Africa in various forms and for various reasons and some have affected the abundance and availability of medicinal species. The widespread practice in Africa of conserving edible wild fruit-bearing trees for their fruits or shade also ensures availability of some traditional medicines as several are multiple-use species. For example the following six trees are conserved for their fruit: Irvingia gabonensis and Ricinodendron heudelotii in west Africa (barks are used for diarrhoea and dysentery); from southern Africa Trichilia emetica (enemas), Parinari curatellifolia (constipation and dropsy), Azanza garkeana (chest pains), and Sclerocarya birrea (diarrhoea). Albizia adianthifolia, used for enemas, is conserved for its shade.

Protection of vegetation at grave sites, for religious and spiritual reasons, is a common feature in many parts of Africa (including Kenya, Malawi, South Africa and Swaziland) and an important means through which biotic diversity is maintained outside core conservation areas. In south-eastern Africa during the nineteenth century, specific Zulu regiments were called up annually to burn fire-breaks around the grave sites of Zulu kings: these woodland or forested sites were considered to be a sanctuary for game animals (Webb and Wright, 1986). An important feature of vegetation conservation around grave sites is that this practice is maintained even under high population densities and tremendous demand for arable land, for example in Malawi. The practice might possibly be strengthened through the burial of prominent leaders in conservation areas.

Religious beliefs have also helped to ensure careful harvesting of Helichrysum kraussii, an aromatic herb known as impepho in Zulu which is widely burnt as an incense in Natal. Diviners are careful not to rip the plant out by its roots (Cooper, 1979).

In Swaziland and South Africa, taboos also restrict the seasonal (summer) collection of Alepidea amatymbica roots, Siphonochilus aethiopicus and Agapanthus umbellatus rhizomes. In each case, collection is restricted to the winter months after seed set as summer gathering is believed to cause storms and lightning. In Zimbabwe, clearance has to be obtained from ancestral spirits before entering certain forests where Warburgia salutaris occurs. In each of the above cases (excepting Agapanthus umbellatus), the species concerned are popular, scarce and effective. These intentional conservation practices may be due to the century-old history of trade in these plants in the southern African region.

Government legislation has played a largely ineffective role in controlling the use of medicinal plants in Africa. Under colonial administration, religious therapy systems practised by diviners were equated with witchcraft and legislated against almost everywhere (Cunningham, 1990; Gerstner, 1938; Staugard, 1985). In South Africa (and possibly other parts of Africa) during the colonial era, there were also attempts to prohibit the sale of traditional medicines within urban areas, such as the efforts made by the Natal Pharmaceutical Society in the 1930s in Durban, South Africa. Apart from having the temporary effect of driving informal sector plant sellers and TMPs underground, this kind of legislation has been ineffective in reducing traditional medicine use. Attempts to suppress traditional medicine are not, however, solely restricted to the colonial era: in post-independence Mozambique, for example, diviners involved in symbolic or magico-medicinal aspects of traditional medicine were sent to re-education camps in an effort to do away with “obscurantism” (Adjanohoun et al., 1984).

Although forest legislation in most African countries generally recognizes the importance of customary usage rights (including gathering of dead-wood for fuel, felling poles and gathering latex, gums, bark resins, honey and medicinal plants) conservation land or certain plant species are often set aside for strict protection (Schmithusen, 1986). In South Africa, for example, forestry legislation was promulgated in 1914 for the protection of economically important timber species such as Ocotea bullata. Specially protected status has been given since 1974 to all species within the families Liliaceae, Amaryllidaceae and Orchidaceae due to their prominence in the herbal medicine trade.

At best, this legislation has merely slowed down the rate of harvesting. Extensive exploitation within forest reserves still occurs in South Africa. One of the main reasons for this is that legislation for core conservation areas (CCAs) in the past has concentrated on a “holding action” to maintain the status quo and neglected to provide local communities with viable alternatives to collecting customary plants.

Dynamics of the commercial trade

If effective action is to be taken to deal with the over-exploitation of medicinal plants, there has to be a clear understanding of the scale and complexity of the problem.

Domestic trade

Africa has the highest rate of urbanization in the world, with urban populations doubling every 14 years as cities grow at 5.1% each year (Huntley et al., 1989). In rural areas throughout Africa, wild plant resources fulfill a wide range of basic needs and are a resource base harvested for informal trade or barter, whereas in urban areas, a much smaller range of species and uses is found. In rural areas of the Mozambique coastal plain for example, 76 edible wild plant species are used (Cunningham, 1988a) but only five species are sold in urban markets in Maputo. Urbanization results in this general reduction in the number of species and the quantities of certain wild plant resources used as people enter the cash economy, and alternative foods, utensils and building materials become available. However, informal sector trade in two categories of wild plant resources continues to be very important in many cities: fuelwood (alternative energy sources such as electricity, gas and paraffin are not available or affordable; Eberhard, 1986; Farnsworth, 1988) and medicinal plants.The range of commercially sold medicinal species in southern Africa remains wide despite urbanization (over 400 indigenous species in Natal, South Africa, for example; Cunningham, 1990). Little attention has been paid to the cultural, medical, economic or ecological significance of the herbal medicine trade, yet traditional medicine sellers are a feature of every African city (ECP/GR, 1983). Cities are concentrated centres of demand drawing in traditional medicines from outlying rural areas and across national boundaries. Despite the differences in volume and range of species used, parallels can be drawn between the trade in medicinal plants and that in fuelwood:

(1) high proportions of people use medicinal plants (70-80%) and fuelwood (60-95%) (Leach and Mearns, 1988);

(2) high urban demand can undermine the rural resource base by causing the depletion of favoured but slow growing species such as Combretum (fuelwood, Botswana; Kgathi, 1984) and Warburgia salutaris (bark medicines, Zimbabwe);

(3) harvesting is a strenuous and labour intensive activity with financial returns, carried out by rural people with a low level of formal education and poor chance of formal employment;

(4) supplies may be drawn from a long distance away - from 200-500 km for fuelwood in many African cities (Leach and Mearns, 1989) and as far as 800-1200 km for certain medicinal plants in west Africa such as Entada africana and Swartzia madagascariensis or Synaptolepis kirkii in southern Africa (Cunningham, 1988a).

The herbal medicine trade is characterized by two features. First, from being almost solely an activity of traditional specialists, medicinal plant collection has now shifted to involve commercial harvesters in the informal sector, and (in South Africa at least) formal sector traders (Table 2) who supply the large urban demand. Women, rather than men, are increasingly involved as non-specialist sellers of traditional medicines, and this general pattern is seen throughout Africa. In rural areas and small villages, male and female TMPs practise from their homes. In larger villages, herbalists (mainly men) dispense from a small quantity of traditional medicines that they have gathered themselves. In towns, larger quantities of material are sold, some of which are bought from commercial harvesters, and in cities or large towns, large quantities of plant material are supplied by commercial harvesters and sold through increasing numbers of informal sector sellers (mainly women) to urban herb traders or herbalists for self-medication. Men drop out of non-specialist sales as it becomes an increasingly marginal activity, and only persist as sellers of animal material. Second, demand for traditional medicines is highly species specific and alternatives are not easily provided due to the characteristics of the plant or animal material, their symbolism, or the form in which they are taken. These large urban areas dictate prices, which are kept low because of rising unemployment, over-supply and cheap labour. Thus nothing is paid towards the replacement of the wild stocks.

In the stressful environment which is a feature of many urban areas in Africa, it is not surprising that demand has increased for traditional medicinal plant and animal materials which are believed to have symbolic or psychosomatic value.

Traditional plant or animal materials which bring luck in finding employment, which guard against jealousy (such as that engendered when one person has a job whilst their peer group are unemployed), or love-charms and aphrodisiacs to keep a wife or girlfriend are popular. Thus, employment options for TMPs have increased with the stresses of urban life. In addition, western-type medical facilities have not been able to cope with the rapidly growing urban population. In Lagos, Nigeria, for example, the ratio of medical doctors to total population was 1 : 5000 in 1975 compared with 1 : 2000 in 1955 (Udo, 1982).

Traditional medical practitioners are therefore attracted to urban centres where employment benefits can be good, as shown in studies in Nairobi (Kenya), Dar es Salaam (Tanzania), Kampala (Uganda), Kinshasha (Zaire) and Lusaka (Zambia) (Good and Kimani, 1980) (Table 1).

In Zimbabwe there is a higher ratio of TMPs to total population in urban areas (1 : 234) than in rural areas (1 : 956) (Gelfand et al., 1985). This is not always the situation, however: in the Kilungu district of Kenya, the ratio of rural TMPs to people averaged 1 : 224, while in urban Mathare, the overall ratio was 1 : 883 (Good, 1987).

Box 1: Case study: The trade in chewing sticks

Dentists are scarce in many parts of Africa, particularly in rural areas. The ratio of dentists: total population in Ghana was 1 : 150 000 (compared to 1 : 3 000 in Great Britain) (Adu-Tutu et al., 1979). Although diet plays a major role in causing dental caries, the practice of dental hygiene is also important. While toothpaste and toothbrushes are widely used by the sector of the population with a high level of formal education, toothpaste consumption is still low (e.g. Adu-Tutu et al., 1979 in Ghana) and chewing sticks are still in common use in many parts of Africa, particularly west Africa. Even when people would prefer to use toothbrushes, they do not have access to toothpaste due to high cost or remoteness. Continued access to popular and effective sources of chewing sticks, which have anti-bacterial properties, is important as a primary health care measure.

While many hundreds of medicinal plant species are used within a region, a smaller number of the most popular species accounts for much of the commercial trade to urban areas. This applies equally to chewing sticks. In Mozambique for example, Euclea divinorum and Euclea natalensis (Ebenaceae) are the most commonly sold species, although other species are used countrywide. In Côte d’Ivoire, the most popular sources of chewing sticks are Garcinia afzelii and Garcinia kola and less commonly used chewing sticks were Zanthoxylum macrophyllum, Maytenus senegalensis, Pycnanthus angolensis and Enantia polycarpa. In Cameroon, only Garcinia mannii and Randia acuminata were the basis of a chewing stick “cottage industry” (Staugard, 1985). Similarly, in southern Ghana, from a sample of 880 people interviewed, six species (distinguished by four local names) accounted for 86% of all usage and the majority of the commercial sales. The majority of all these respondents depend on bought material rather than collecting it themselves, irrespective of size of settlement they live in or their educational status (Figure 2). The species used were: nsokodua (Garcinia afzelii and G. epunctata (51.1%; 597 people); tweapea (Garcinia kola (18.7%; 218); sawe (Acacia kamerunensis and Acacia pentagona (9.2%; 108); and owebiribiri (Teclea verdoorninana (6.7%; 77).

Figure 2. A. Acquisition of usual chewing stick by buying (shaded columns) and collecting (open columns) among people of various sizes of settlement (after Cunningham, 1988a) B. Acquisition of usual chewing stick by buying (shaded columns) and collecting (open columns) among people differing in educational background (after Adu-Tutuet al. , 1979).

International trade

The herbal medicine trade is booming business worldwide. In India, for example, there are 46 000 licensed pharmacies manufacturing traditional remedies, 80% of which come from plants (Alok, 1991). Another example is Hong Kong, which is claimed to be the largest market in the world, importing over US$ 190 million annually (Kong, 1982). In Durban (South Africa), in 1929 there were only two herbal traders; by 1987, there were over 70 herbal trader shops registered. The species specific nature of the demand for medicinal plants is responsible for generating long distance trade across international boundaries. According to Malla (1982), 60-70% of the medicinal herbs collected in Nepal are exported to India, with 85-200 tons exported annually between 1972 and 1980. Similarly the Hong Kong market imports Aquilaria heart-wood for incense manufacture from rain forest in Thailand and Malaysia. This is devastating Aquilaria populations in core conservation areas such as Khao Yai National Park, Thailand (Cunningham, pers. obs.; Cunningham, 1988a; Cunningham, 1988b). Africa is no exception to this pattern and an informal sector trade in medicinal plants spans long distances:

(1) the roots of Swartzia madagascariensis and Entada africana are traded 500-800 kms from Burkina Faso and Mali to Abidjan, Côte d’Ivoire;

(2) the roots of Synaptolepis kirkii are traded 1200 km from the southern border of Mozambique and South Africa, via Johannesburg, to Maseru (Lesotho);

(3) the bark of Warburgia salutaris is traded from Swaziland to Johannesburg (South Africa) and Namaacha (on the Swaziland/Mozambique border) to Maputo (Mozambique);

(4) the roots of Alepidea amatymbica and bark of Warburgia salutaris are traded from the Eastern Highlands (Zimbabwe) to urban centres in the west of the country such as Bulawayo;

(5) mail-order trade in traditional medicines is common in South Africa (Figure 3).

Figure 3. Long distance trade in Natal province, South Africa, from the remotest rural areas to major urban centres through formal and informal trade networks, including mail order sales.

An average of 25% of prescription drugs sold in the USA during the period 1959-1973 contained active principles extracted from higher plants (Farnsworth and Soejarto, 1985). Many of these are derived from the same source as those used in traditional medicine. On a global scale, 74% of these chemicals have similar or related uses in traditional medicine (Farnsworth, 1988). Similarly, many African plant species are the source of a number of active ingredients for the export market (Table 3, Photo 2). Because of the low price demanded by plant traders, even when technology for chemical synthesis is available, it can be cheaper for pharmaceutical companies to continue to extract the active ingredients from plants. In the mid-1970s, for example, synthesis of reserpine cost $1.25 g-1, compared to a cost of $0.75 per g-1 for commercial extraction from Rauvolfia vomitoria roots (Oldfield, 1984).

According to the UNCTADD/GATT International Trade Centre, the total value of imports of medicinal plants for OECD countries, Japan and the USA increased from US$ 335 million in 1976 to US$ 551 million in 1980 (Husain, 1991). Of the 200 tons of Harpagophytum procumbens and H. zeyheri tubers exported annually from Namibia, Germany imported 80.4%, with the remaining 12.8% sold to France, 1.9% to Italy, 1.5% to USA, 1% to Belgium and 1.2% sold locally or to South Africa (Nott, 1986). Unfortunately, the low prices paid for the plants do not cover replacement or resource management costs, and as such, major importers demanding high volumes of plant material are contributing to the decline of medicinal plant species in Africa.

Photo 2. Medicinal plant seller at a market in Abidjan, Côte d’Ivoire, showing the dominance of fresh leaf material as a source of herbal medicines.