Perception of malaria and cultural diversity of antimalarial plants in three sympatric ethnic groups: Agni, Akyé and Gwa of Alépé Department (Southeast of Côte d’Ivoire)

Ethnic groups have developed their own cultures expressed in the form of traditional health care systems. This study aimed to determine how three sympatric communities with different histories, perceive and manage malaria, a disease with a high prevalence rate in the region. An ethnobotanical survey was carried out in 10 villages of Agni, Akyé and Gwa communities. Semi-structured interviews were conducted with 290 informants within all three communities. A correspondence analysis associated to hierarchical clusters was used to determine the form of malaria shared within informants. Then, the free listing technique was performed to indicate the plant species which was most important for the respondents. Besides, the Venn diagram coupled to Jaccard similarity index was used to report the homogeneity on antimalarial plants species used within the three studied communities. Moreover, the Kruskal-Wallis test was used to compare the most common antimalarial plant within communities. Finally, the delity level index was used to identify the most preferred plant species used to cure various forms of malaria.


Introduction
Medicinal plants are one of the most widely known values of traditional knowledge, as they provide primary health care [1]. Certainly, traditional medicine is an important source of health care in rural or tribal areas [2,3]. In sub-Saharan countries such as Côte d'Ivoire [4,5], Mali [6] and Guinea [7], people still use traditional medicine to cure many diseases as malaria.
Malaria is among the major vector-borne diseases that kill a lot of people in sub-Saharan Africa [8]. That disease constitutes a real public health issue and motivates the consultation and hospitalization in sanitary centres [9]. However, the raised costs of the sanitary cares lead many people in rural areas, to use traditional medicine as alternative for curing malaria [10]. Even so, in an intercultural region, a given ethnic group could know some species which may not be appreciated by another ethnic group or may even be ignored by them [11]. To that purpose, they do not use and value all plant species equally according to their needs in the same practice [12]. Those reasons could hide a variation in the perception of a particular disease and a different signi cance of plants for those communities [13], especially while they share the same geographical area with other communities [14].
In Africa, particularly in Côte d'Ivoire, numerous studies dealing with medicinal plant uses are simple lists of plants [15] or ethno-pharmacology uses against malaria [4,16]. Moreover, they were undertaken solely on intra-cultural background. Other studies in the same way, were undertaken for many diseases [17].
Comparative ethno-botanical studies among communities who share the same area are scarce.
Nevertheless, such studies help to nd which species are interchanged through communities and for which reasons [1,18]. Moreover, those studies analyse whether cultural diversity is re ected in the folk phytotherapy knowledge as shown by [11]. These authors argued, as noted by many others [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]19] that the comparative study of medicinal plant knowledge among sympatric ethnic and/or local groups may be divided into two types. The rst type focuses on traditional groups with comparatively long residence in the region and the second type concentrates on the comparison of medicinal plants use by ethnic groups with different times of residence in a given region. The present study is within the rst statement. Indeed, in the Department of Alépé, in the southeastern region of Côte d'Ivoire, the Agni, Akyé and Gwa ethnic groups have lived in close proximity and contact for many centuries in the Department of Alépé. Agni and Akyé belong to the great Akan ethnic group [20][21][22][23], whereas Gwa ethnic groups were adopted by Akan [24,25]. Although close to the economic capital, Abidjan, this area is extremely di cult of access due to the poor state of the roads. Moreover, these communities are among those whose traditional practices are the least documented. Finally, these communities are in malaria high transmission zone with 200 to 300 con rmed cases per 1,000 inhabitants per year [26]. In the light of these backgrounds, the study aimed to (i) analyse the perception of different forms of malaria and (ii) to assess the importance of antimalarial plants species used among these ethnic groups. Moreover, this study aimed (iii) to determine the intracultural and the intercultural variations on antimalarial plant knowledge within ethnic groups.

Study area
The Department of Alépé is located in Southeastern Côte d'Ivoire between 5°13'04.49" -5°55'22.06" N and 3°25'25.25" -3°57'46.64" W ( Figure 1). The climate of this zone is equatorial and humid, characterized by four alternate seasons (two rainy seasons and two dry seasons). The annual rainfall is ranged from 1,200 to 1,600 mm and the annual temperature is 26.4°C with a variation of 3°C. The vegetation type of the study area is a Guinean rainforest characterized by Eremospatha macrocarpa (Mann. & Wendl.) Wendel. and Diospyros mannii Hiern [27].
The study area harbors three sympatric ethnic groups Agni, Akyé and Gwa. All of them are unequally spread within ve sub-prefectures (Aboisso-Comoé, Alépé, Allosso, Danguira and Oghlwapo). These three ethnic groups have been settled in their present territory since the beginning of the 18th century, the Agni and the Akyé from present-day Ghana [22,23], and the Gwa from Liberia [24,25]. Upon arrival, these ethnic groups came into con ict for their current installation [28]. All three ethnic groups are essentially farmers.

Ethnobotanical survey
Several eld trips were made in 10 villages of the study area from September 2017 to August 2019. A total of 290 informants were selected randomly with semi-structured interview [29]. At rst step, free lists were collected through a house-to-house approach in each village. The seek items included forms of malaria, symptoms related to the forms of malaria, plants used for healing malaria.
Respondents were distributed as follows: 97 in Agni ethnic groups (40 men and 57 women), 97 in Akyé ethnic groups (35 men and 62 women) and nally 96 in Gwa ethnic groups (47 men and 49 women). For next step, walks in the surrounding bushes were organised with key informants in each village, to collect herbarium vouchers. At the nal step, the lists collected during the rst step was completed and herbarium vouchers identi ed at Nangui Abrogoua University.

Data analysis
A correspondence analysis (CA) combined to a hierarchical cluster analysis was performed in order to show the forms of malaria sharing between ethnic groups. The principle of this analysis is to establish the link between two sets of variables that constitute the rows and columns of a contingency table. This analysis was carried out with the frequency of quotation of the form of malaria by each ethnic group.
That frequency of quotation was obtained to assess the extent of form in each ethnic group (Equation 1).
Where F q is the frequency of quotation; n i is the number of times when the form of malaria was mentioned, and N is the total number of informants. When F q ≥ 50% the form is considered as well known. Below this value, the form can be judged middle known 25 ≤ F q ≤ 50% or low known F q < 25%.
Free listing technique was performed by Anthropac 4.0 following the Smith Index (Equation 2) in order to obtain the salience for each species [30].
Where S is the importance of quotations, Li the length of a quotation list and Rj the rank of a quotation in the list and N is the number of free lists (number of respondents). A high value of this index (close to 1) indicates the antimalarial plant species which is preferred and important for the respondents.
In addition, the Jaccard similarity Index [31] was used to analyse the homogeneity on antimalarial plants species and reports the similarity within the three studied communities (Equation 3).
JI is the Jaccard similarity index, a is the number of species common to any compared pair ethnic group i and j; b is the number of species mentioned only by group i, and c is the number of species mentioned solely by group j.
Then, the speci c abundance shared by each pair of ethnic groups or exclusive to one ethnic group and the common species shared between the three ethnic groups were obtained with Venn diagram. This diagram shows the number of antimalarial plant species shared between ethnic groups. Moreover, a comparison test on the most common antimalarial plant species shared within the ethnic groups, were made with Kruskal-Wallis test. This test determines the intercultural convergence on knowledge exchanges between the ethnic groups.
Finally, the delity level (FL) index (Equation 4) was used to identify the preferred plants to heal various forms of malaria and shows the proportion of informants reporting the use of speci c plants [32].
Where Np is the number of respondents citing the use of species for a particular ailment and N is the total number of respondents who cited the plants for any form. All statistical analyses were performed with R software (version 4.0.3).

Results
Knowledge and perception of malaria by the three ethnic groups Six various terms are used to indicate six different forms of malaria according to each ethnic group (Table 1). Among these six different forms of malaria, ve are expressed with symptoms. Meanwhile, the mystical malaria, another form appears without symptoms. Thus, the most common form is yellow malaria mentioned by 72.16% of informants, which means yellowish eyes, yellowish urine and fever. Then, white malaria identi ed by 58.76% means pale skin and edema. Besides, red malaria is indicated by 42.61% which means fever and reddish eyes. Moreover, black malaria is identi ed by 24.74%, means fever and dark skin. Otherwise, 5.15% of informants have mentioned bird malaria which means disjointed movements, fever and pale skin. Finally, the mystical malaria is indicated by 1.37% of informants without symptoms. Table 2 summarizes the symptoms mentioned in the study. The free lists on the form show that each ethnic group has mentioned two forms of malaria on average, in spite of the various forms of malaria (Fig. 2).

Page 8/27
The distribution of the forms of malaria within the ethnic groups is divided into two groups, according to the frequency of quotation (Table 3). The rst group (G1) included the forms mentioned by Gwa ethnic groups. Meanwhile, the second group (G2) is formed by the forms mentioned by both Agni and Akyé ethnic groups (Fig. 3).
The distribution on the form of malaria was not signi cantly different (Chi squared = 0.6874296; p-value = 0.9999699). Agni and Akyé ethnic groups are closer on forms of malaria than Gwa ethnic groups (Fig. 4).

Diversity and intercultural relations of antimalarial plant species
Seventy-seven (77) species, distributed in 71 genera and 38 families were collected ( Table 4). The most represented families were Lamiaceae, Asteraceae and Leguminosae with ve species. They were mainly composed of 67 trees and shrubs, 10 herbaceous plants and one liana. All values are below 0.5 i.e 50% which means that there is a low knowledge sharing of antimalarial plants species (Table 5). Thus, Akyé are closer to Gwa ethnic groups whereas, the knowledge of Agni ethnic groups is speci cs of them. (S Agni =0.15; F qAgni =22.68%) and Senna occidentalis (L.) Link (S Agni =0.15; F qAgni =21.65%). Figure 6 shows two plant species most important in the study area.
The delity level (FL) of the recorded plants was less than 40% suggesting that none of them are really speci c to a particular form of malaria. Thus, the plants of high cultural values mentioned above are frequently used to cure various forms of malaria (Table 6). The intracultural analysis of antimalarial plants lists suggested that knowledge is widely shared in each community (Fig. 7) as the level of saturation of the respondents was quickly reached: after the 15th respondent out of 97 in Agni, the 19th out of 97 in Akyé and the 17th out of 96 informants in Gwa ethnic groups.
However, the Gwa recorded the longest lists (average = 4 plants), followed by the Agni (average = 4 plants), and then the Akyé with an average of three plants (Fig. 8).

Discussion
This study aimed to analyse the perception of various forms of malaria in three sympatric ethnic groups with various sociolinguistic backgrounds. Different terms were used to indicate six forms of malaria across ethnic groups. This diversity on the forms of malaria is not unique to our study area. In fact, in Africa several studies have shown various communities whose have distinguished many forms of malaria. For example, in Mali the communities of Sélingué subdistricts, have identi ed malaria through ve forms sumaya, nènèdimi, djontè, djokoadjo and farigan [6]. Besides, in Zimbabwe, in the Chipinge District, traditional healers have recognized two forms of malaria, muswarara and ndangaranga [10]. However, the knowledge on the symptoms changes from one ethnic group to another. In fact, this variation of the symptoms was allowed to distinguish a simple form and a serious form of malaria. Thus, the symptoms as disjointed movements, fever, pale skin have been frequently reported by the ethnic groups in our study area. In the similar observations, the communities of Chipinge in Zimbabwe have mentioned those symptoms [10]. Moreover, in Mali the Sélingué communities have considered convulsions as an uncomplicated symptom of malaria [6]. Traditional medicine distinguishes a varied range of symptoms. Those symptoms evolve from one country to another. In fact, the variations of symptoms depend on traditional practices and cultural backgrounds [33,34]. Better, those variations depend on the accessibility of rural communities to conventional medicine [10]. Therefore, local perceptions of malaria can be matched to conventional medicine. In fact, conventional medicine distinguishes two main forms of malaria (simple and complicated form) with many variations [35]. However, traditional medicine as well as conventional medicine cannot cope some disorders as mystical malaria and cerebral malaria. Those di culties have conducted to the integration of traditional medicine in the region health system [6][7][8][9][10]33].
However, the high transmission of malaria creates a tendency for people to catch that disease. Indeed, the susceptibility to the malaria changes from one country to another according to cultural backgrounds and was revealed by the ethnic groups behavior. In fact, the immunogenetic factors might be taken in account for distinguishing the susceptibility to malaria [34]. For example, in Mali two sympatric communities have been compared. Their studies have shown that in spite of fever which is a common symptom of malaria, Peulh communities are more susceptible to catch malaria than Dogon communities.
Traditional medicine is a part of people's culture and is closely linked to their beliefs. In fact, people combine religion, sorcery and interpersonal con ict into a single form of belief and practice [36]. As an example, Amazonian people of Upper Rio Negro of Brazil associated malaria to spiritual beings and used to be cured with the blessings of shamans [37].
However, the other issue raised in this study is the importance of antimalarial plants species. As well as mentioned by some authors [37,38], the use of plants depends on the culture. Indeed, the doctrine of signatures [39], has been used as a means to understand the medicinal plant selection process in traditional cultures. Moreover, for some authors [40] in Mexico and in Côte d'Ivoire [17], the organoleptic properties (bitter taste of bark stems and leaves or yellow color of the bark stems and the shape of plant organs) indicate that a given plant, has a medicinal potential and a therapeutic application. Thus, several studies have con rmed the antiplasmodial activities of the most important antimalarial plant species mentioned in this study. For example, stem bark of Annickia polycarpa [41], stem bark of Nauclea latifolia [42], stem bark of Harungana madagascariensis [43], leaves of Gymnanthemum amygdalinum [44], leaves of Ocimum gratissimum [45] and leaves of Senna occidentalis [46] were con rmed e ciency to manage malaria and related symptoms. However, the stem bark of Alstonia boonei was revealed inactive for inhibition concentration higher than 50 µg/ml against Plasmodium falciparum in, in vitro culture [43]. Even so, this plant species was prescribed against shiver and aches [15] in both Côte d'Ivoire and Ghana.
For example, in Ghana, the leaves of Alstonia boonei have shown that the alkaloid extract of the species have an anti-plasmodial activity at 8.4 µg/ml [47]. Thus, the e ciency of a given plants depends on the parts of plant which were used differently by people to treat malaria [48].
Although the most important antimalarial plants above, have already been mentioned in literature for their antiplasmodial activities, there is no reference in the literature describing some antiplasmodial activities about Blighia unijugata Baker, Diospyros sanzaminika A.Chev., Cola nitida (Vent.) Schott & Endl., Macaranga barteri Müll.Arg., Parkia bicolor A.Chev., Plectranthus monostachyus (P.Beauv.) B.J.Pollard, Tarrietia utilis (Sprague) Sprague and Vitex grandifolia Gürke. These plant species were less known in our study. Nevertheless, these plant species are known for their analgesic, feverishness and antianaemic properties [15], which represent remedies against certain symptoms of malaria. There is a lack of information exchanges about their uses among informants [3,9].
On the other hand, the similarity rate between antimalarial plant species was under 50%. The geographical proximity of ethnic groups have in uenced the local culture in the uses of medicinal plants [39,49]. For example, in Pakistan, the communities of Dhirkot, Azad Jammu and Kashmir which share the same vegetation, have the same knowledge on the medicinal plants [3]. In the similar case, the communities of Allada in Benin have shared their knowledge [9].
The different cultural backgrounds have explained, however the uses of plant species to cure malaria. In fact, in our study the greatest amount of plant species was recorded in the family of Lamiaceae, Asteraceae, Leguminosae and Apocynaceae, whereas, in Abidjan plant species belonging to Rubiaceae, Combreataceae, Leguminosae and Meliaceae families were mainly used for their antimalarial properties. Therefore, trees and shrubs were more used than herbaceous plants. Inversely, in Brazil herbaceous plants were observed by [50].
The last issue of this study is to determine the intracultural and intercultural variations of the knowledge within ethnic groups. Thus, the local knowledge on plant uses was in uenced by the culture of people which included ethnic group, language, acquired practical experiences [14]. As an example, in the North-East and Central-East of Côte d'Ivoire, four Agni tribes used wild edible plants in two different vegetation.
Agni-Barabo and Agni-Bini shared their knowledge [51]. In fact, they shared the same migration histories, the same religion and the same vegetation 49]. Meanwhile, the intercultural variation on the common antimalarial plant species, was not signi cantly different, in this study. Indeed, the common plant species usually shared, are actively used through time and are considered effective. For example, in the South-Central of Ethiopia, four ethnic communities living in two different areas (Gurage, Mareqo, Qebena and Silti), have used the common plants and on the same time are considered effective [13,48].
In contrary, two ethnic groups Koulango and Lobi, living around the East side of the Comoé National Park of Côte d'Ivoire, were compared about the availability of wild edible plants [52]. These authors have shown in their studies that, in spite of their close contact, Koulango and Lobi ethnic groups like differently wild edible plants. In fact, their studies have revealed that the uses of a given wild plant species are speci c to one ethnic group and its culture [12,39]. Otherwise, the knowledge sharing depends on the ethnic groups [13], and the preference of the plant species uses [12]. For example, 14 different ethnic groups in the Northern of Benin, were compared through the uses of the parts of Parkia biglobosa (Jacq.) G.Don [53]. In their studies, local knowledge varied from one ethnic group to another according to the form of uses and the organs of Parkia biglobosa, in the same geographical area. In fact, Lokpa, Waama and Bariba ethnic groups assigned high consensus value for bark, leaves, roots, seeds and pulp. In contrast, Nago, Anii, Dendi, Otamari, Mokolé, Foodo, Yom, Berba, Boko and assigned low value to bark and leaves. For the different form of uses of Parkia biglobosa, there is a consensus values for decoction, condiments were high for Bariba, Dendi, Fulani, Waama and Lokpa but low for other ethnic groups.
On the other hand, the extent of the knowledge on the medicinal plants according to the FL, changes from one country to another. As an example, in the rural communities of Dhirkot, Azad Jammu and Kashmir in Pakistan, preferred different plants to cure speci cally wound healing, gastrointestinal disorders, body weakness, diabetes and cough [3]. In conclusion, traditional medicine plays a signi cant role in local people's daily life. In spite of their different migration histories, the close contact of these ethnic groups promote the sharing of the knowledge. In fact, people use the same important plants to cure malaria and know overall ve forms of malaria. Exceptionally, Akyé and Gwa ethnic groups know both the sixth form, mystical malaria, due to their geographical proximity. Knowledge on antimalarial plants in study area does not reach a stable climax, but could be evolved by trial and error, as effective cures malaria.

Declarations
Ethics approval and consent to participate The present study is purely based on a eld survey instead of humans. Before starting investigation, the chief of each investigated village was informed on the research project. Then, an agreement was needed to residents prior to start questions following the recommendations of the International Society of Ethnobiology Code of ethics for the publication of this research and any accompanying images.    Venn diagram representing abundance of species used against malaria between ethnic groups of the study area.