Ethnomedicinal study of plants used in the Uvira Territory (Democratic Republic of Congo)

Abstract This study aimed to investigate the ethnomedicinal plant knowledge among people living in The Uvira Territory. The data were collected using semi-structured interviews with and field observation in seven villages. The ethnomedicinal data was analyzed using the informant consensus factor (ICF), family importance value (FIV), and Jaccard index (JI). Sixty-nine medicinal plants belonging to 61 genera and 34 families were used to treat eight disease categories. Fabaceae was not only the dominant family but also a family with the high FIV. Decoction and pound were the most common methods of preparation, while leaves were the most used part. We compared this study with 24 other ethnomedicinal studies conducted in RD Congo and neighboring countries, and the results showed that the Jaccard index ranged from 0.57 to 10.94. The highest degree of similarity (10.94) was found with another study conducted in Congo, while the lowest degree of similarity (0.57) was found with a study conducted in Rwanda. The disease category for which there was the highest number of use (66) and plant species (39) was “diseases of the digestive system disorders and intestinal parasites” (ICF 0.42). The investigation of the plants used as drugs in the study area revealed that the population daily relies on medicinal plants to treat different diseases.


Introduction
The use of plants to treat and cure diseases is as old as the human species (Gurib-Fakim 2006;Oliveira et al. 2011;Arshad et al. 2014), and they are considered essential in human health care (Asadi-samani et al. 2013). Moreover, plants provide firewood, timber, and fodder for livestock. This knowledge evolves across cultures and over time and space (Pieroni and Giusti 2009). Furthermore, each ethnic group has an acquaintance and know-how specific to its historical, cultural, and even spatial environment (Shalukoma 2008), representing an invaluable reservoir of skill and considerable potential for yet undiscovered use of natural resources (Balima et al. 2018).
Approximately 80% of the population in developing countries still rely on medicinal plants (Mugisha and Origa 2005;Mahomoodally 2014). The modern health system is often available only to a restricted number of people. Either the amenity is too expensive, or few facilities are accessible for too many people (Ahmed et al. 2018). For this reason, medicinal plants are still a source of medical care in developing countries (Tabuti et al. 2003).
In D.R. of Congo, 69.6% of the population live in rural areas, and 30.4% live in urban areas (Kabinda et al. 2015). Still, given socio-economic realities which do not allow them to access modern health care, they rely on medicinal plants (Kitadi et al. 2019;Chiribagula et al. 2020).
Although previous studies explored the medicinal plants in Sud-Kivu over the last two decades (Schneider 1996;Chifundera 1998Chifundera , 2001Shalukoma 2008;Mangambu et al. 2012;Balagizi et al. 2013;Kasali et al. 2013;Mangambu et al. 2014;Amani et al. 2015;Balagizi et al. 2015;Shalukoma et al. 2015;Mangambu et al. 2015aMangambu et al. , 2015bShalukoma et al. 2016), little is known about ethnomedicinal research within Uvira Territory. Two studies were carried out in low altitudes of the Uvira Territory: Manya et al. (2020) surveyed anti-malarial herbal of Bukavu and Uvira areas, and Byavu et al. (2000) focused on the ethnoveterinary of cattle. Therefore, implying the assessment of ethnomedicine plants has a great potential to provide essential new insights into the knowledge of some plant species. Our work investigated the ethnomedicinal plants used by the local people in the Uvira Territory.

Study area
Our ethnomedicinal investigation has been conducted in seven different villages within Uvira Territory: Kirungu, Shenge, Kalonge, Munanira, Kitala, Gomba, and Kifuta ( Figure 1). All these villages are located in the middle plateau of the Territory. The altitude of this area ranged between 1334 and 2078 m, with an oceanic climate (Cfb) according to the Koppen climate classification (https://en.climate-data.org). The population largely depends on subsidence agriculture and livestock farming. Farming is based on a rain-fed cropping system, and the main crops of the area are cassava (Manihot esculanta) and Corn (Zea mays).

Ethnobotanical surveys
During this investigation, 25 traditional healers were interviewed. Information on traditional knowledge related to ethnomedicine was collected through a semistructured interview conducted in local languages (Fuliiru or Vira) with the help of interpreters. The choice of respondents relied extensively on the professionalization of healers in the communities. An oral agreement was obtained from the participating communities. A survey sheet was submitted to the healers, and the person was asked to give the various diseases that people often consult the healers. The information focused on plants of the recipe, parts used, preparation methods, and administration route. Each time after investigating a traditional healer, a field observation was conducted to collect the specimens. The information for each species, including scientific name, family, local name (Fuliiru or Vira), morphological type, plant parts used, preparation, disease name, and plant habitat, were also collected. The conservation status of plant species was checked in the International Union

Botanical identification
Voucher specimens of the plants were harvested. The identification of the recognized species was made in the field for the species identified by using some books for spelling and name confirmation (Letouzey 1982;Fischer 1993). Scientific names were updated to currently accepted names according to the plant list (www.theplantlist.org). The collected vouchers were compared with the previously specimens conserved at the herbarium of the Natural Sciences Research Center of Lwiro (CRSN/Lwiro) for the unidentified species, where family and scientific names were confirmed. Voucher specimens were prepared and deposited in the herbarium of the Natural Sciences Research Center of Lwiro.

Quantitative analysis
Various quantitative indices were calculated to test the homogeneity of the collected medicinal plants: Informant consensus factor (ICF): It was calculated using the following formula (Tilahun and Mirutse 2010;Bakwaye et al. 2013, Mahomoodally 2014: where Nur is the number of use reports in each disease category and Nt is the number of species used. Family importance value (FIV): This metric is the number of informants citing the family (FC) divided by the total number of informants participating in the study. It gives the local importance of a family (Kayani et al. 2014): Jaccard index (JI): The Jaccard index was used to compare the similarity of named species between our data with studies already published that were where A is the recorded number of species of the current study, B is the documented number of species of another study, and C is the number of species common to both studies.

Demography profile
A total of 25 healers were interviewed. Out of these, 92% were male, and 8% were female. According to the age of the interviewee, the healers were classified into four groups. The age group of 41_60 was observed to have the highest (36%) participation rate, followed by the healers aged! 60 years (28%). The group healers aged between ages 31_40 and 21_30 years corresponded to 24% and 12% of our sampling universe, respectively ( Table 1).

Diversity of the ethnomedicinal plants and habitat
Through this study, a total of 74 medicinal plants was inventoried. Of these, 63 were identified down to species level, six were identified only to the genus level (Cassia sp, Hibiscus sp, Musa sp, Oxalis sp, Rubus sp, Syzygium sp), and five plants were not identified. The 69 medicinal plants identified represented 61 genera and 34 botanical families. Forty-five species were harvested from their natural environment, 33 were either fallow or ruderal species, and 12 were cultivated ( Figure 2). That is similar to other studies that reported that almost all plants were harvested from nature (Megersa et al. 2013). The recorded plant diversity shows that out of the 69 species, 64 were dicotyledons (93%). Four species were monocotyledons (6%), and one was a Pteridophyte (1%) ( Table 2).
Seven families (out of 34) provided 43.5% of the medicinal species. The dominant families were the Fabaceae (eight species), followed by the Asteraceae (six species), Myrtaceae (four species). All the remaining families were either represented by three, two, or one species (Appendix). Our results agree with similar research conducted in the DRC (Ngbolua et (Islam et al. 2014;Faruque et al. 2019). Similar findings were also observed in the neighboring countries Ngezahayo et al. 2015;Tugume et al. 2016;Salinitro et al. 2017).
Almost all genera (n ¼ 57) were represented by only one species. Three genera were represented by two species, i.e., Ficus, Persicaria, and Syzygium. The genus with the highest amount of species was Albizia, with three representatives. The investigation on the plant morphological type showed that herbs were the kind of plants most reported for medicinal uses, with 32 species, followed by trees and shrubs (13 species each) and sub-shrubs (11 species) (Figure 3). The frequent use of herbaceous species could result from their relative abundance compared with trees and shrubs (Giday et al. 2010).

Plant parts used, preparation methods, and administration route
The analysis of the plant parts used as medicine by the healers showed that the leaves were the most commonly utilized plant part in drug preparations,   . By considering the recipe preparation mode of traditional medicines, reports include decoction, infusion, pound, concoction, maceration, and ash. Among these, the pound was the principal preparation method (34%), followed by decoction. However, other preparation methods, such as maceration, chewing, and squeezing, are used, albeit to a lesser frequency (Figure 3). These findings agree with Inta et al. (2008), who reported that the pound was typical of herbal preparation in the Chinese Akha communities. However, in opposition to other researches, the decoction was the most commonly used method (Lesetsa et al. 2017;Umair et al. 2019).
Most healers suggested taking herbal medicines orally (53%), and the dose ranges from half glass to one glass thrice a day (Figure 4).

ICF, FIV and JI
The documented medicinal plants were utilized to treat 41 different illnesses grouped into nine categories, and the plants were distributed according to the categories (shown in Table 3). "Respiratory and the cardiovascular" were the ones with high ICF value (0.5), followed by the "diseases of the digestive system and intestinal parasites" (ICF 0.42) and "dermatological diseases" (0.22). The mean ICF for all illness categories was 0.19. Among the illness categories, "diseases of digestive system disorders and intestinal parasites" were dominant with 66 use-reports, followed by "dermatological diseases" and the "reproductive system and related disorders" (19 and 16 use-reports, respectively), as shown in Table 3. Approximately 56.5% of plants were used to treat "digestive system disorders and intestinal parasites," followed by "dermatological diseases" (21.7%) and "diseases of the reproductive system and related disorders" (18.8%).
Among the 34 plant families with medicinal uses, all families had the FIV below 0.5. The botanical family with high FIV was Fabaceae with 0.42, followed by Myrtaceae and Asteraceae (0.38, 0.31 respectively). Polygonaceae, Myricaceae, Malvaceae, Lamiaceae, and Euphorbiaceae had 0.19, respectively ( Figure 5). In a comparative analysis of medicinal plant use in Uvira Territory within RD Congo and the four neighboring countries, 24 published articles were used. Only 66 species that were identified to species level were considered for the purpose. The high degree of similarity index in the DRC area was with the studies of Shalukoma et al. (2015), Mangambu et al. (2015a), which reached JI values of 10. 94, 10.38, Balagizi et al. (2013), and Nyakabwa and Dibaluka (1990), 8.63 respectively, and the lowest similarity index was with Bakwaye et al. (2013) with a JI value of 0.88 (Table 4). Compared with the neighboring countries, the similarity index values between Ngezahayo et al. (2015); Asiimwe et al. (2013) and our area were 8.43 and 7.35. Moreover, the low similarity was with Munyaneza et al. (2006) with JI value of 0.57 (Table 5).

Conservation status
The excessive collection of timber, fuelwood, food plants, and commercial exploitation of medicinal plants has provided a great deal of vulnerability to plant species (Chhetri et al. 2005). The conservation status of all recorded plant species was checked using the International Union for Conservation of Nature    (Anacardiaceae)) was recorded as "data deficient", while others species were not recorded.

Conclusion
This study carried out in the middle plateau of the Uvira Territory revealed the daily used of medicinal plants to cure several diseases. Local people used sixtynine medicinal plant species to treat 41 various illnesses. Diarrhea, stomachaches, hemorrhoid, and sexual impotence were frequently cited as diseases. The most medicinal plants known by the local people include Syzygium guineense, Tetradenia riparia, Plantago palmata, Agauria salifolia, Ricinus communis, Myrica salicifolia, Parinari curatellifolia, Erytrina abyssinica, Trema orientalis, Rhus vulgaris, Maessa