Ethnomedical survey and safety evaluation of traditional eye medicines used in Misungwi district, Tanzania

Abstract

Aim:

This study aimed at documenting products used as traditional eye medicine (TEM) in Misungwi district, Tanzania, and performing preliminary analysis on safety status.

Methodology:

Ethnomedical study was conducted in Misungwi district. Information was sourced by face-to-face interview with traditional healers, traditional medicine vendors, and knowledgeable people guided by a well-structured questionnaire. Safety was evaluated by determining pH using pH meter and mineral analysis using the Delta, Portable X-ray fluorescence equipment, and qualitative chemical tests.

Results:

A total of 23 TEM products were recorded from botanical (79%) and zoological (21%) sources including animal excreta. Liquid preparation ranked highest among dosage forms. Safety evaluation showed that only one product possessed the pH value of 7.4 as recommended for topical ophthalmic medicines. Fourteen minerals were detected and quantified in three samples; some of these minerals are known for their negative effects to the eyes, of medical interest is strontium used for the management of benign eye tumors. Information providers were unaware of health risks associated with the use of TEM.

Conclusion:

This study has revealed the common use of TEM in Misungwi district. The majority of the products are from the botanical source. Although literature provides supporting data for the application to some of the recorded TEM, safety evaluation by pH and mineral analysis in this study have indicated possible ophthalmological medical problems that could result from using such products. Extensive scientific studies including animal experiments and identification of bioactive compounds are essential to develop safe TEMs.

INTRODUCTION

Eyes are delicate sensory organs that make our everyday life comfortable. When it comes to treatment, eyes require special attention to avoid medical problems including partial or total vision disability. In Tanzania, modern health-care services are inadequate and majority of population especially in rural areas still rely on traditional methods including the use of traditional eye medicine (TEM). Various studies have associated TEM with medical eye problems based on diagnosis made by medical practitioners/ophthalmologist, for example, a study conducted in Tanzania showed that 25% of corneal ulcers resulted from the use of TEM [1] and a similar research conducted in Malawi showed 33% of patients with corneal disease in rural Malawi reported to have used TEM [2]. In the same country, 72% of the interviewee on self-treatment used TEM with no clear borders between biomedical and herbal medicines, i.e., used side by side [3].

TEM products are obtained from botanical, zoological, and mineral sources, and routes of administration are local application to eyelids, eye drops, instillation into the conjunctival sac, or taken orally [4]. Negative consequences of using TEM could be minor such as temporary irritation and pain or major such as permanent loss of vision if not timely and well managed. Examples include the following; Calotropis procera latex reported to cause significant ocular morbidity, including painless corneal edema, permanent endothelial cell loss with morphological alteration after intracorneal penetration ending up with keratitis [5-7] and a case study reported in Nigeria where man suffered from ocular discomfort and eventually blindness after applying the raw cassava extract [8]. Recently, Tanzanian plants and other products used for the treatments of eyes diseases/conditions were published in a systematic manner to enable quick search for further scientific research to prove their efficacy and safety [9].

Tanzania is among the African countries rich in natural resources that provide medicinal substances for traditional health care. Misungwi district mainly populated by the Sukuma tribe is a place where traditional medicine is still valued, especially among old people and the rural population. It involves the use of all sorts of natural resources and supernatural powers. It is one of the seven districts of Mwanza region in Northern part of Tanzania situated in the savannah grassland about 156 km from the Serengeti national park at 02°51’S 033°05’E. Its map is given in Figure 1. The area has tropical climate, the summers have a good amount of rainfall, while the winters have very little. According to the Köppen-Geiger climate classification, the temperature averages 23°C and the rainfall averages 901 mm [10].

Figure 1.

Map of Misungwi district [11]

This study aimed on documentation of TEM products in Misungwi district as a way conservation of such knowledge and performing preliminary safety evaluation by pH determination and mineral analysis. Our findings are expected to stimulate researches on TEM products on various aspects to enable preparation of standardized TEM product/identify useful bioactive compounds for the development of ophthalmic products.

METHODOLOGY

Study Design

This study was conducted in two phases as follows:

1. Ethnomedical study comprised oral interview and field work done on alternate days

2. Safety evaluation included laboratory work.

Ethnomedical Study

Study period, study site, and information providers (IPs)

The study was carried out for 14 days in December 2014 in Misungwi district and covered Mapilinga, Mwaniko, Nange, and Ng’ombe villages plus the Misungwi street in town. Interviewee included traditional healers and knowledgeable people (KP) found at homes in the villages whereas traditional medicine vendors were found at the business center of the town.

Data and material collection

The purpose of the study was explained, and informed consent was obtained from each of the participants. Face-to-face oral interview was conducted in Swahili (national) and Sukuma (local language) to obtain reliable information using a well-structured questionnaire (Annex I), which was translated to Swahili language. The data on TEM including sources, dosage forms, preparation methods, route of administration, knowledge, and awareness of IPs on risks associated with TEM were immediately recorded in the questionnaire. Field work involved collection of plant material for herbaria preparation, pH determination, and mineral analysis. Samples of animal excreta were bought from IPs. Identification/authentication of collected plants using herbaria specimen was done in the Botany Department at the University of Dar Es Salaam where the voucher specimen were deposited.

Quantitative ethnomedical data analysis

The collected information was quantitatively analyzed using an index of relative frequency citation (RFC) as,.

This index shows the local importance of each product and it is given by the frequency of citation (FC), the number of informants mentioning the use of the product (species) divided by the total number of informants participating in the study (N) [12].

Safety Evaluation

This was performed in February 2015. The pH determination was done in the Laboratory of Pharmacognosy Department at Muhimbili University of Health and Allied Sciences and mineral analysis in the Geology Department at University of Dar es Salaam.

Determination of pH values

Determination of pH values employed the JENWAY 3035 pH meter, made in the UK by Jenway Felsted Dunmow, Essex CM6 3LB. Sample preparation was done according to the method previously described by Maregesi et al. [9] with minor modification at room temperature of 25°C. In brief, 1 g of the powdered material of each test sample was weighed in triplicate then macerated with 20 mL distilled water with occasional shaking for the period of 12 h. The filtrates were used for pH determination. The pH of each sample was obtained by taking the average value from triplicate analysis.

Mineral analysis

Mineral analysis was carried out using Portable X-ray fluorescence (XRF) spectrometer, and the application note by Innov-X systems, 2003, was adopted. Each test sample was ground to a very fine powder and then passed through a sieve of 250 µm mesh. About 100 mg of each sample was weighed and then transferred into respective XRF test cups which were then covered tightly with nylon material. The XRF test cups containing samples were then subjected to the analyzer (XRF spectrometer) for spot analysis (Innov-X systems XRF testing guideline). Additional mineral analysis was done using standard procedures/reagents for qualitative tests of salts.

RESULTS

Ethnomedical Study

Eighteen IPs participated in the study whose demographic data are presented in Table 1. Number of males and KP were higher than females and others groups, respectively. We afforded to record twenty-three TEM products and their methods of preparation, dosage forms, administration routes, FC, and RFC as summarized in Column A of Table 2. Frequency of mention of treated disease/conditions is presented in Figure 2. All IPs were neither aware of any health risks associated with the use of TEM nor making follow-ups on patient progress. In case of treatment failure, patients could opt to report back to get an alternative medicine or seek treatment from other sources including modern medicine.

Table 1.

Demographic data of information providers

Table 2.

TEMs used in Misungwi district

Figure 2.

% Frequency of mention of the treated eye disease/condition

Safety Evaluation

All tested products were alkaline in nature with the pH values ranging from 7.3 to 10.0 as shown in Table 3. Fourteen minerals detected/quantified in three TEM products are given in Table 4. Hyena excreta ranked highest for the total number of detected minerals.

Table 3.

pH of traditional eye medicine products

Table 4.

Mineral contents of the excreta and sea snail shells

DISCUSSION

Ethnomedical Study

The majority of the recorded TEM products (79%) are obtained from plants with half of them prepared from leaves. Animal products comprised of honey (4%) and animal waste (17%). The suitability of the later for use as eye medicines is doubted since microbial contamination with pathogenic microbes is most likely as evidenced by lizard droppings [9]. The majority of reported products are liquid preparations applied as eye drops (91%) and matching with topical ophthalmic solution most commonly used and accepted dosage forms in modern medicine [46]. Most of the recorded TEM products were mono-component except for the following: (i) Ficus glumosa, Ficus natalensis, and Nicotiana tabacum; (ii) lizard and hyena excreta; and (iii) lemon juice and salt – a containing common and easily available substances.

Aloe vera leaf juice (latex) was the most mentioned product with the RFC of 0.61 followed by Euphorbia hirta and Vernonia amygdalina each with RFC of 0.43. About 61% of the recorded TEM products had previously been reported in Tanzania or other parts of the world for treatment of the same or different eye problem(s). This is a good indication on reliability of the information obtained from IPs. Previous data including those of related species are summarized in Column B of Table 2.

Itching, sand, and tearing eyes are common symptoms of allergic conjunctivitis [45]. In this context, allergic conjunctivitis is the most common treated eye disease/condition constituting 39% of all cases. It is normal that common diseases in a particular society tend to have more attention and various medicines. Allergic conjunctivitis is likely to be the most common eye problem as it relates well to the climate of Misungwi district and especially during the dry season with blowing winds that carry various dust particles capable of causing some allergies.

Chemical constituents of TEM products render therapeutic effects through various biological/pharmacological activities such as antimicrobial, anti-inflammatory, analgesic, and wound healing. For example, (i) honey is used against eye infection and eye itching, the former can be related to the antimicrobial activity of honey in aerobic conditions brought about by the osmotic effect of its sugar contents, hydrogen peroxide produced by the action of the enzyme glucose oxidase in diluted honey and phytochemicals found in the nectar including flavonoids and aromatic acids [47]; (ii) management of wounds resulting from conjunctivitis/irritation may be linked with the wound healing activity of E. hirta whose probable mechanism of action is promotion of collagen biosynthesis [24]; and (iii) curative effect of Cocos nucifera shell charcoal could be due to adsorption of foreign substances causing red eyes or minerals dissolved in the aqueous solution.

An interesting observation from this study is the use of related species for treatment of a particular eye disease/condition as reported for Crotalaria and Ficus species. Based Based on chemotaxonomy, i.e., related species contain same/related phytochemicals thus likely give the same therapeutic effects as reported by the IPs. Another observation was that the concept of eye diseases was not clear among few IPs who regarded insomnia as an eye problem simply because it involves closure of the eyes by reporting Datura stramonium to treat this condition which is in accordance with the known use of the plant [22]. In addition, IPs were able to specify different eye diseases/conditions as compared to those from previous studies, who gave generalized information.

The lack of awareness and follow-up of the patient is a drawback on this particular traditional medical service. The fact that treatment the failure oblige patients to the seek treatment from modern medical services is in agreement with observation made in studies conducted in Tanzania and Malawi [1,2] and elsewhere. The unfortunate part is that the harm could have reached an irreversible stage by the time patients consult the medical practitioner/ophthalmologist due to switching from one or more TEM until desperation.

Safety Evaluation

Among the six analyzed samples, the python excreta micella was the only TEM with the recommended pH of ophthalmic products of 7.4 which is the same as that of the lacrimal fluid due to isotonicity importance. However, pH values of 7-9 are tolerated by the eye without marked irritation. Acidic and too alkaline products are corrosive to the eye [48]. Regarding the pH of V. amygdalina leaf extract, it was alkaline (pH of 7.6) compared to the acidic pH of 5.6 in our previous work [9]; at this point, no definitive comment can be made but just to speculate the causes such as unspecified age of leaves collected from different locations.

With regard to minerals, some metals causes toxicity by their action on the retina and optic nerves and are implicated in structural and physiological damage in the mammalian eye [49]. Some of the negative health effects of the detected metals and salts include vision impairment by manganese [50], chemical burn of eyes and skin by rubidium hydroxide formed from the reaction between rubidium and skin moisture [51], redness, pain and inflammation by calcium carbonate [52], skin and eye irritation by zinc salts particularly the carbonate [53], granuloma caused by zirconium and arsenic being carcinogenic [49]. Thus, frequent use of TEM containing these minerals could lead to medical eye problems. On the other hand, strontium has medical application for management of benign tumors of the eye [54].

This study and literature data show the role of TEM in various communities despite reported harmful consequences of some TEM products [5-9] and lack of evident scientific support to justify their uses. However, the use of TEM is inevitable due inadequate modern health services, thus a need to educate the public about health risks associated with TEM through the media and other means. In parallel, scientists should focus their research to produce standardized, safe TEM products and/or identify bioactive compounds for the development of modern medicine.

CONCLUSION

The findings of this study showed that majority of the recorded TEM products (79%) are botanical products while animal products (21%) comprised of honey and animal wastes. Some of the recorded products have previously been reported in Tanzania/other countries, suggesting that the information given by IPs is reliable but this not a guarantee for efficacy and safety. IPs and the public as a whole need to be informed on risks associated with the use of TEM. Results from safety evaluation, though preliminary, necessitate a very comprehensive study to identify safe TEM products as well as getting evidence for public declaration of unsafe products. Animal experiments to establish the safety status of some botanical TEM products are in progress.

ANNEX