Mailu et al. Chin Med (2020) 15:95 https://doi.org/10.1186/s13020-020-00374-2 Chinese Medicine RESEARCH Open Access Medicinal plants used in managing diseases of the respiratory system among the Luo community: an appraisal of Kisumu East Sub-County, Kenya James Kiamba Mailu1,2* , Joseph Mwanzia Nguta1, James Mucunu Mbaria1 and Mitchel Otieno Okumu1,3 Abstract Background: Poor access to healthcare in rural communities causes many people to seek herbalists who use medici- nal plants for the treatment of various disease conditions. Most knowledge of traditional herbal medicine makes use of indigenous remedies which are often undocumented and are at risk of being lost. The preservation of this knowl- edge may facilitate scientifc inquiry into promising new therapeutic molecules. Methods: Semi-structured questionnaires were used to collect the sociodemographic information of 30 herbalists in Kisumu East Sub County. The local names of medicinal plants used in managing illnesses of the respiratory system, their habit, active parts, indications, methods of preparation, routes of administration, scientifc identity, and conserva- tion status were also recorded. Other reported traditional uses, pharmacological activities, and toxicological data were identifed via a literature search. Results: Most herbalists were female (86.7%), aged between 61 and 70 years (43.3%) with no formal education (56.7%), and had 21–30 years of practice (30%). 44 plant species, belonging to 43 genera and 28 families were identi- fed. Leguminosae and Rutaceae plant families were predominant, leaves were frequently used (33%), and trees were the most common habit (44.4%). Most plants were collected in the wild (79.2%), preparation was mainly by decoction (68.8%), and the administration was mainly orally. The main indication was cough and 79.5% of all documented plant species had previously been reported to have a pharmacological activity relevant to the mitigation of respiratory ill- nesses. Toxicological data was available for 84.1% of the plant species identifed. Conclusions: The predominant use of roots, root barks, and root tubers by herbalists in Kisumu East Sub County threatens to negatively impact the ecological survival of some plant species. The preservation of herbalists’ knowl- edge of medicinal plants in the study area is a pressing concern considering their advanced age and little formal education. There is a need to conserve some of the medicinal plants documented in this study. The medicinal claims made by herbalists also warrant scientifc scrutiny. Keywords: Ethnopharmacology, Medicinal plants, Kisumu East, Luo, Ethnomedicinal, Ethnobotanical, Respiratory diseases, Cough Background *Correspondence: [email protected] Te global burden of respiratory diseases makes for 1 Department of Public Health, Pharmacology, and Toxicology, Faculty of Veterinary Medicine, University of Nairobi, P.O Box 29053-00625, daunting reading. Lower respiratory tract infections Nairobi, Kenya (LRTI) and chronic obstructive pulmonary disease Full list of author information is available at the end of the article (COPD) reportedly claimed 6 million human lives in © The Author(s) 2020. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creat iveco mmons .org/licen ses/by/4.0/. The Creative Commons Public Domain Dedication waiver (http://creat iveco mmons .org/publi cdoma in/ zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data. Mailu et al. Chin Med (2020) 15:95 Page 2 of 27 2016 [1]. Te prevalence of COPD in Sub Saharan Africa longitudes 33° 20′ E and 35° 20′ E and comprises of sev- has been reported to be between 4 and 25% and > 100,000 eral administrative wards including Kolwa Central, deaths have been linked to non-communicable diseases Kolwa East, Manyatta B, Nyalenda A, and Kajulu East including those of the respiratory system [2, 3]. Diseases and West [10]. Moreover, the population in this area is of the respiratory system hurt individual productivity about 220,977 according to the 2019 Kenya Population and are responsible for more than 10% of all disability- and Housing Census [5]. It receives an annual relief rain- adjusted life years [4]. fall of between 1200 and 1300 mm and annual tempera- According to a 2013 Kenya National Bureau of Statis- tures range between 20 and 35 °C. Te major economic tics (KNBS) economic survey, pneumonia, and tubercu- activities of residents include fsh farming, and agricul- losis were responsible for 13.7% of all total deaths in the ture (sugar, livestock, and poultry farming) [10]. Nyanza region [5]. It is important to note that illnesses of the upper respiratory tract are the second leading cause Data collection of death in Kisumu County [6]. Poor access to health- Te study was conducted between March and September care and scarcity of health resources in rural areas such 2019. Ethnobotanical data were obtained by using semi- as many parts of Kisumu East Sub County causes many structured questionnaires. Te target respondents were inhabitants of such areas to rely on indigenous plant local herbalists with good ethnobotanical knowledge resources to manage common diseases including those of the plants used in managing respiratory diseases and that afect the respiratory system. Plant-based indigenous related symptoms. Tirty local herbalists were selected remedies may be key in the future management of respir- for interviews which were conducted both in Kiswahili atory system diseases [7]. However, the potential of this and Luo dialect with the aid of a botanist familiar with resource is largely untapped due to inadequate documen- the languages. Each of the respondents was interviewed tation by the herbalists who prepare the remedies. individually to ensure confdentiality. Te interviews Te rapid development of infrastructure in Sub Saha- sought to answer the following questions; ran Africa including Kenya threatens to destroy cultural lands where medicinal plants are cultivated. Tis is prob- • Which plant parts are most commonly used in pre- lematic given that the knowledge of these plant resources paring the indigenous remedies indicated for respira- is mostly an extension of people’s culture [8, 9]. Herb- tory illnesses? alists are usually the custodians of medicinal plants in • Which methods are adopted in preparing the indig- these communities. By documenting the knowledge held enous remedies? by herbalists, vital information on the medicinal plants • Which respiratory illnesses are most commonly may be preserved. Te current study aimed to collect treated with medicinal plants in the study area? ethnobotanical data on medicinal plants used by herbal- • Which plant species are used in the preparation of ists in the management of respiratory diseases in Kisumu the remedies? East Sub County. • How are the indigenous remedies administered? See Additional fle 1. Materials and methods Ethical approval and consent to participate in the study Ethical approval for the study was obtained from the Collection and identifcation of plant specimens Biosafety, Animal Use and Ethics committee of the Several trips were made to the homesteads of the herbal- University of Nairobi (Ref: FVM BAUEC/2019/210). ists where voucher specimens were collected and pressed Approval was additionally sought from regional admin- and later identifed by a botanist before being deposited istrators (the area chief and assistant chief) who were at the University of Nairobi Herbarium. Information on duly notifed of the study’s objectives. Te scope, possible the vernacular name, plant part used, plant habit (i.e. the benefts, and risks of the study were explained to willing general appearance, growth form, or architecture), plant participants (herbalists) and consent forms were made status, method of preparation, and route of administra- available to them for signing. tion were collected. Study area Literature search strategy Te study was conducted in Kisumu East Sub County A literature search was conducted on MEDLINE, Pub- in Western Kenya (Fig. 1). Te study area is approxi- Med, PubMed Central (PMC), Google Scholar, the mately 365 km from Nairobi (the administrative capital Directory of Open Access Journals (DOAJ), Te Journal of Kenya) and covers an area of approximately 135 km2. Author Name Estimator (JANE), University reposito- It lies within latitudes 0° 20′ South and 0° 50′ South and ries, and from grey literature to identify relevant articles/ Mailu et al. Chin Med (2020) 15:95 Page 3 of 27 Fig. 1 Map of Kenya showing Kisumu County and Kisumu East Sub County theses/ reference material containing information on where Fc is the number of herbalists who cited a par- previously reported traditional uses, pharmacological/ ticular species and N is the total number of herbalists chemical activities, and toxicological data on the medic- (Table 1). inal plants indicated for the management of respira- tory illnesses in Kisumu East Sub County. Studies were Results excluded if they were not in English. Socio‑demographic characteristics of the herbalists who were interviewed Data analysis 86.7% of all herbalists were female, and aged between 61 Frequencies and percentages were used to analyze the and 70 years of age (43.3%) (Table 1). Te average age of sociodemographic data of the herbalists. Te relative fre- the female herbalist was 61.6 years while the average age quency of citation (RFC) was used to evaluate the ethno- of their male counterparts was 51.5 years of age.