Ethnobotanical Survey of Medicinal Plants and Practices of Traditional Healers in North Pemba Region of Zanzibar: Implications for Sustainable Use and Conservation

Khamis Rashid Kheir ¹ , Mayassa Salum Ally ¹ , Farid Mzee Mpatani³ , Ussi Makame Kombo³ , Hassan Buda Juma¹ , Moh'd Mshenga Matano² , Sauda Rashid Ismail¹ , Khadija Ali Khamis ¹ , Ame Masemo Ame ¹ , Rashid George Rashid¹ , Kombo Moh'd Kombo¹ , Thani Ame Ali¹ , Mwanaidi Yahya Kafuye¹ , Ali Mohamed Ali ¹ , Bilali Badrudin Khamis ¹ , Salum Ali Ahmada¹ , Bariki Salum Juma¹

¹Zanzibar Health Research Institute (ZAHRI), P.O. Box 1439, Zanzibar, Tanzania

²Zanzibar Traditional and Alternative Medicine Council, P. O. Box 236, Zanzibar, Tanzania

³Chief Government Chemist Laboratory Agency, P. O. Box 759, Zanzibar, Tanzania

⁴National Institute for Medical Research, Mabibo Traditional Medicine Research Center, P. O. Box 9653, Dar es salaam Tanzania

Corresponding Author Email: khamiskheir9@gmail.com

DOI : https://doi.org/10.51470/ABP.2025.04.03.78

Abstract

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1 Introduction

Medicinal plants constitute a fundamental component of primary healthcare for millions of people worldwide, particularly in regions where biomedical services are limited or culturally less preferred [1, 2]. According to the World Health Organization, up to 80% of the population in developing countries relies on plant-based traditional medicine for basic healthcare needs [1]. In East Africa, traditional healing systems play a especially central role due to their accessibility, affordability, deep cultural roots, and perceived efficacy in managing both common and chronic ailments [3, 4].

Zanzibar, an archipelago located in Tanzania, has a rich history of traditional medicine influenced by African, Arab, and Swahili cultural traditions [5, 6]. Traditional healers known locally as waganga wa kienyeji or watabibu remain integral to community health structures, particularly in rural areas where formal health services may be insufficient [7, 8]. Despite its cultural importance, traditional medical knowledge in Zanzibar faces increasing threats from environmental degradation, changing socio-economic dynamics, and inadequate documentation [8, 9].

North Pemba, the northern region of Pemba Island, is particularly rich in plant diversity owing to its tropical forests, coral rag zones, and coastal ecosystems [5, 10]. Its communities possess extensive knowledge of medicinal plants used to treat a wide range of ailments including fevers, gastrointestinal disorders, reproductive health problems, and respiratory conditions [7, 11, 12]. However, this knowledge is at risk of erosion as younger generations show reduced interest in learning from elder healers, and plant habitats face increasing pressure from land-use changes and climate-related stressors [12, 13]. The findings of the present study will be very crucial to the government and non-government sectors including policymakers in order to document and conserve the knowledge and identified traditional medicines. Therefore, the current study aim is to document medicinal plant use, traditional healing practices, and conservation of medicinal plants in North Pemba, with a view to inform sustainable utilization and policy development

1.1 Graphical Flowchart

Study area → Healer selection → Questionnaire survey → Plant identification → Data analysis → Documentation and Recommendations

2 Materials and Methods

2.1 Study Area

This study was conducted in the North Pemba Region, located in the northern part of Pemba Island, Zanzibar, Tanzania. The North Region has two districts (Wete and Micheweni Districts). A tropical climate with bimodal rainfall characterizes North Pemba, diverse vegetation types (including coral-rag thickets, lowland forest, and coastal bushland), and ecologically critical habitats such as the Ngezi Forest Reserve, the island’s last remaining closed-canopy forest [10, 5]. The region comprises small, rural Shehias with mixed livelihoods based on subsistence farming, fishing, and small-scale trade [6, 7]. Figure 1 of the present study shows the map of Pemba Island, including its four districts.

2.2 Study Design

A cross-sectional ethnobotanical survey was conducted using qualitative and quantitative techniques consistent with established ethnobotanical research protocols. The study involved: Semi-structured interviews, Free listing, Guided field walks, and Participant observation.

Data were collected from 21 January to 3 February 2019 through semi-structured interviews and field visits with traditional healers in selected Shehias of North Pemba. Healers provided information on medicinal plants, including local names, preparation techniques, and therapeutic uses, while field visits allowed observation of plants in their natural habitats or home gardens. Data reliability was enhanced through triangulation, comparing responses from different healers and validating information through direct observation.

2.3 Sampling and Data Collection

2.3.1 Sampling Approach                                    

A purposive sampling strategy was employed to identify traditional healers, herbalists, bone setters, midwives, and spiritual healers recognized by their respective communities. Snowball sampling was then used to identify additional practitioners. A total of 182 traditional healers and herbal practitioners participated across 23 Shehias of the North Pemba Region.

2.3.2 Data Collection Procedures

The study employed three ethnobotanical data-collection methods. Semi-structured interviews lasting 30 – 60 minutes were conducted in Kiswahili to gather information on medicinal plants used, their local names, harvested parts, preparation methods, treated disease categories, plant sources, perceived threats, knowledge transmission, and healers’ attitudes toward regulation and conservation, with responses later translated into English. Free listing was used to document all medicinal plants commonly used by participants, allowing assessment of cultural importance, salience, citation frequency, and identification of core medicinal species. Guided field walks involved accompanying healers to forests, farms, and homesteads to identify plants in their natural environments, verify local names, collect voucher specimens, and document ecological conditions. Plants were taken to a botanist to determine the scientific name of each plant.

2.4 Data Analysis

Qualitative data on healer perceptions, perceived threats, and knowledge transmission were analyzed using inductive thematic content analysis, allowing recurrent themes to emerge directly from the responses. Quantitative data were analyzed using descriptive statistics, with variables summarized as percentages, means, and standard frequencies. The results were presented in tables and figures generated with SPSS v.25 and Excel.

2.5 Ethical Considerations

Ethical clearance was obtained from the Zanzibar Health Research Institute (ZAHRI) Research Ethics Committee.

3 Results

3.1 Demographic Characteristics of Traditional Healers

A total of 182 traditional healers and herbal practitioners participated in the study across the 23 Shehias of North Pemba. Participants were predominantly male, and most were above 40 years of age, reflecting the seniority and experience typically associated with traditional healing roles in Zanzibar.

The majority (92.3%) reported practicing without formal registration or certification. More than half had practiced for over 20 years, and knowledge was primarily transmitted through family lineages or apprenticeship, with only a small proportion reporting self-taught skills.

Table 1 of this study summarizes the demographic characteristics of Traditional Healers in the North Pemba Region.

3.2 Diversity of Medicinal Plants Documented

A total of 96 medicinal plant species belonging to 89 genera and 47 families were documented in the study area (Appendix 1). The most species-rich families were Euphorbiaceae (10 species), Lamiaceae (6 species), Rutaceae (6 species), and Asteraceae (5 species). This high level of species richness highlights the considerable ecological diversity of North Pemba and underscores the long-standing cultural reliance of local communities on plant-based therapies for healthcare. Figure 2 of the current study shows the distribution and frequency of medicinal plants reported by practitioners during the visiting study sites.

Figure 2: Distribution and frequency of medicinal plants reported by practitioners

3.3 Cultural Importance and Frequency of Citation

The study revealed high cultural salience for medicinal plant species used in the treatment of fever, malaria, stomach disorders, reproductive ailments, and respiratory problems. Among these, the five most frequently cited species were Erythrina abyssinica, Guilandina bonduc, Cissampelos pareira, Moringa oleifera, and Ocimum suave. The Use Value (UV) of the recorded species ranged from 0.12 to 0.83, with E. abyssinica exhibiting the highest UV, indicating its prominent importance in local traditional medicine.

3.4 Disease Categories Treated and Plant Parts Used

3.4.1 Diseases Categories

Medicinal plants were employed to treat a wide range of health conditions, which were classified into seven major disease categories: fever; gastrointestinal disorders such as diarrhea, stomachache, and worm infestations; reproductive health issues including infertility and menstrual problems; respiratory ailments such as cough, flu, and asthma; musculoskeletal disorders including pain and rheumatism; skin conditions; and spiritual and psychosocial ailments. Among these categories, fever accounts for the highest number of uses, followed by gastrointestinal disorders and respiratory problems, highlighting their prominence in local healthcare practices.

3.4.2 Plant Parts Used

Leaves were the most used plant part in medicinal preparations, followed by roots, bark, whole plant, fruits, and seeds. While the predominant use of leaves is relatively sustainable, the substantial reliance on roots and bark raises conservation and sustainability concerns, as harvesting these parts can severely affect plant survival and long-term availability. Figure 3 of this study reveals part of the medicinal plant and its frequency of use.

3.5 Preparation and Administration Methods

Medicinal plants were prepared using a variety of techniques, with decoction being the most common method, involving the boiling of plant materials, followed by crushing, maceration, decoction with additives, and vapor therapy (Table 2).

In terms of administration, oral intake was the predominant route, followed by topical application, shower, gargle, and vapor therapy, reflecting both therapeutic and traditional practices in the use of medicinal plants (Table 3).

3.6 Sources of Medicinal Plants and Conservation Status

3.6.1 Source of Medicinal Plants

In figure 4, the survey revealed that medicinal plants were primarily sourced through wild collection by the practitioners, representing 120 responses. A smaller yet notable proportion of around 36 respondents reported that they obtained plants through gatherers and collectors while purchasing from middlemen and cultivating or farming medicinal plants were comparatively rare.

3.6.2 Conservation Status

Traditional healers identified overharvesting and climate change, particularly unpredictable rainfall patterns, as the two most significant threats to the availability of medicinal plants. Additional pressures included habitat loss, soil degradation, urbanization and road construction, and invasive species. Many healers reported a noticeable decline in the abundance of key medicinal species, notably Warburgia salutaris, Zanthoxylum chalybeum, and Guilandina bonduc, underscoring growing conservation concerns.

3.7 Knowledge Transmission and Practice Regulation

Knowledge of traditional medicine was predominantly transmitted within families, although many healers expressed concern about declining interest among younger generations. Despite this challenge, there was strong support for formalization of the practice, with 94.9% of healers favoring government recognition, 91.7% endorsing regulation and training, and 87% supporting the cultivation of medicinal plants. Additionally, 72% of respondents were open to collaboration with biomedical practitioners, highlighting a clear willingness among healers for structured integration of traditional medicine into Zanzibar’s formal health sector.

3.8 Harvesting methods

Common harvesting methods reported by respondents included digging (51%), cutting (39%), uprooting, harvesting or picking (28% each), and stripping (19%). Some respondents used multiple methods in combination. Figure 5 reveals the methods taken by practitioner in the collection process of medicinal plants.

3.9 Beliefs, Culture, and Regulation

When asked why people prefer herbal medicine, (41.2%) respondents highlighted preference due to perceived safety and alignment to cultural traditions, (31.3%) cited ineffectiveness of conventional treatments, (24.2%) emphasized affordability, and a small number of respondents (3.3%) noted lack of health facilities nearby (Figure 6).

4. Discussion

4.1 Diversity of Medicinal Plants and Cultural Significance

This study documented 96 medicinal plant species across 47 families, underscoring the botanical richness of North Pemba and the depth of traditional knowledge embedded within local communities. The high representation of families such as Euphorbiaceae, Lamiaceae, Rubiaceae, and Asteraceae aligns with ethnobotanical findings across East Africa, where these families contribute significantly to traditional pharmacopoeias due to their abundance and diverse of secondary metabolites [14, 15].

The prominence of species such as Erythrina abyssinica and Guilandina bonduc reflects their multiple therapeutic applications and widespread cultural acceptance. These species are also reported in mainland Tanzania, Kenya, and Uganda as key remedies for fever, malaria, and inflammatory conditions, indicating shared pharmacological value across the region [16, 17]. Their high frequency of citation and broad use-value in this study demonstrate their central role in community healthcare.

4.2 Treatment of Major Health Conditions

Medicinal plant use in North Pemba is highly aligned with the local disease burden. The documented dominance of therapies for fever, gastrointestinal disorders, reproductive problems, and respiratory ailments corresponds with prevalent health challenges in Zanzibar and Sub-Saharan Africa broadly [18]. The strong alignment between plant use and disease burden reinforces the clinical relevance of local ethnomedicinal knowledge and highlights its potential complementary role in modern health systems.

4.3 Preparation Methods and Pharmacological Implications

The dominance of decoctions and oral administration mirrors preparation techniques widely reported in African ethnomedicine. Decoction is well-suited for extracting bioactive compounds, particularly alkaloids, flavonoids, and tannins from woody tissues, roots, and bark [19]. This preparation style may contribute to the perceived effectiveness of treatments for fever, infections, and gastrointestinal disorders.

However, the reliance on roots and bark raises concerns regarding sustainability. Harvesting these parts can compromise plant survival and regeneration. Similar trends in Ethiopia, Kenya, and Ghana have been linked with population declines of slow-growing medicinal species [20, 21].

4.4 Dependence on Wild Harvesting and Sustainability Concerns

The overwhelming reliance on wild harvesting,particularly from sensitive areas significant conservation challenge. Traditional healers reported noticeable declines in several species over the past decade, consistent with ecological assessments indicating forest degradation and pressure on rare or slow-growing plants.

Two key threats identified, overharvesting and climate variability,are consistent with global patterns in tropical ethnobotany. Climate change has already shifted phenology, reduced biomass productivity, and altered species distribution across East African coastal ecosystems [13]. Particularly vulnerable species include: Warburgia salutaris (a critically endangered species in parts of Africa), Guilandina bonduc (heavily harvested for antimalarial use) and Zanthoxylum chalybeum (declining due to excessive bark removal) [13]. These findings highlight the urgent need for conservation strategies that combine cultivation, regulation, habitat protection, and community-based natural resource management.

4.5 Knowledge Transmission and the Risk of Erosion

Knowledge transmission in North Pemba remains strongly family-based, consistent with studies across East Africa and the Indian Ocean region. Elders expressed concern that younger generations show decreasing interest in learning healing practices due to: Formal schooling, Migration, Modern healthcare availability, and changing cultural values [22].

This mirrors trends documented in Madagascar, Mauritius, and mainland Tanzania, where traditional knowledge is eroding despite ongoing reliance on herbal medicine [23].

Without proactive documentation and revitalization programs, the North Pemba Region risks losing invaluable cultural and medicinal heritage. The identification of 96 species in this study represents a snapshot of knowledge that may continue to decline unless systematically preserved.

4.6 Willingness for Regulation, Collaboration, and Integration

A notable finding was the overwhelming support for: Government recognition (94.9%), Registration (92.3%), Training (91.7%), Cultivation programs (87%), and Collaboration with the biomedical sector (72%). This level of willingness is significantly higher than reported in comparable studies in Kenya, Ethiopia, or Uganda, where healers often express fear of losing autonomy or intellectual property [24, 25].

In Zanzibar, healers appear motivated by: Desire for legitimacy, Protection of their practices, Improved access to patients, Avoidance of legal challenges, and Concern for declining plant resources. This provides a strategic opportunity for the Zanzibar Ministry of Health, Zanzibar Health Research Institute (ZAHRI), and Zanzibar Traditional and Alternative Medicine Council to establish a formal pathway for integration and alignment with the WHO Traditional Medicine Strategy (2021–2030). Integration could enhance the safety, quality, and efficacy of herbal medicines while preserving cultural heritage.

4.7 Conservation and Policy Implications

The findings highlight critical conservation priorities:

1. Promotion of on-farm cultivation of high-demand species
2. Regulation of harvesting practices, including restrictions on root and bark collection.
3. Strengthening protection of Zanzibar Forests and other biodiversity-rich habitats.
4. Development of community nurseries and herbal gardens.
5. Documentation and digitization of local knowledge.
6. Establishment of a Traditional Healers’ Registry with training modules on safety, dosage, quality control, and conservation.

Such measures would align with national and regional biodiversity conservation frameworks, including the Tanzania National Biodiversity Strategy and the East African Community conservation priorities.

4.8 Contribution to Ethnobotanical Research

This study contributes several new insights:

1. It provides one of the most comprehensive ethnobotanical assessments in North Pemba, covering 23 Shehias/Wards.
2. It identifies species of conservation concern based on local ecological knowledge.
3. It highlights healers’ strong readiness for integration and sustainable practice, a finding underrepresented in East African literature.
4. It creates a baseline for future research on pharmacological validation, conservation interventions, and cultivation programs.

By documenting plant use, cultural practices, and conservation challenges together, this study offers a holistic understanding of how traditional medicine systems function within island ecosystems.

5. CONCLUSION AND RECOMMENDATIONS

5.1 Conclusion

This study provides a comprehensive ethnobotanical assessment of medicinal plant use and traditional healing practices across 23 Shehias in North Pemba, Zanzibar. A remarkable 96 plant species were recorded, underscoring the ecological richness and cultural depth of traditional medicine in the region. Medicinal plant knowledge remains central to community health, addressing widely prevalent ailments such as fever, gastrointestinal disorders, reproductive health problems, and respiratory conditions.

However, the findings highlight concerning sustainability challenges. More than 65% of medicinal plants are harvested from the wild, with heavy reliance on ecologically sensitive areas such as Ngezi Forest. Overharvesting, particularly of roots and bark, together with climate variability, habitat degradation, and low cultivation rates, poses significant threats to medicinal plant populations. Species such as Guilandina bonduc, Zanthoxylum chalybeum, and Warburgia salutaris are especially vulnerable.

Traditional knowledge remains vibrant but fragile. As knowledge transmission is still largely family-based and dependent on aging practitioners, the risk of erosion is substantial. Yet, practitioners demonstrated strong willingness to support formal recognition, regulation, training, and conservation initiatives, offering a unique opportunity to integrate traditional medicine within Zanzibar’s health system in a culturally respectful and sustainable manner.

Overall, this study underscores the urgent need for coordinated conservation strategies, policy interventions, and documentation efforts to safeguard medicinal plant resources and the associated cultural heritage. In the North Pemba Region, traditional medical knowledge represents an invaluable asset for public health and biodiversity conservation, warranting sustained scientific and policy attention.

5.2 Recommendations

Based on the findings of the current study, the following recommendations shall be addressed for further research on:

a) Developing and evaluating integrated conservation strategies that combine cultivation, community-based ex-situ conservation, regulated harvesting, habitat protection, and ecological assessment of high-demand and vulnerable medicinal plant species to ensure their sustainable utilization.

b) Examining the effective models for integrating traditional medicine into formal health systems through healer registration, capacity-building, collaborative practice with biomedical professionals, and the development of culturally appropriate policy frameworks aligned with WHO guidelines.

c) Validation of medicinal plants through phytochemical and pharmacological studies, systematic documentation and digitization of traditional knowledge, interdisciplinary collaboration, and long-term monitoring of ecological and climate-related impacts on medicinal plant resources.

d) Exploration of effective community-based awareness, youth engagement, and livelihood-support models that enhance capacity building while promoting sustainable harvesting and long-term conservation of medicinal plant resources.

5.3 Acknowledgement

The authors acknowledge the Revolutionary Government of Zanzibar through the Second Vice President’s Office for the research permit, the office of the Regional Commissioner of North Pemba Region, for their collaboration in assisting the collection of data from Traditional healers through Sheha (Village leaders).

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