- The Efficacy of Plant Preparations of Myrsine africana and Hagenia
abyssinica as Anthelmintics in
Paper presented at:
International Conference of Medicinal Plants, Traditional Medicines &
Local Communities in Africa: Challenges & Opportunities of the New
Millenium, Nairobi, Kenya 16-19 May 2000
By:
Githiori J1, 2, 3, Höglund J2, Waller P J2, Mugambi J M3, and Baker R L3
1KETRI, Muguga, Kenya; 2SWEPAR, Uppsala, Sweden; 3ILRI, Nairobi, Kenya
Abstract
Livestock production in smallholder farming is constrained by helminth
infections in Kenya. The main method of helminth control is by use of
anthelmintics. However widespread resistance have been recorded and poor
quality, or adulterated, anthelmintics are marketed. In the search for
alternative methods of helminth control, interest in traditional animal
health care and herbal medicine, otherwise referred to as
ethnoveterinary medicine, has been rekindled. With regard to the latter,
two plants Myrsine africana and Hagenia abyssinica, which have been
reported to be used in Kenya, were tested for anthelmintic efficacy in
sheep. Each of 47 sheep was orally infected with 5000 L3 Haemonchus
contortus larvae. After three weeks the animals were randomised into
three groups of at least 15, based on their faecal egg count (FEC) and
live weights (LWT). Two groups were treated with one of the two plants
according to recommended methods of preparation, while the third was an
untreated control. In each treatment group, animals received the
commonly reported dose rate, half, or twice this dose (with 5 animals
per dose rate). Animals were monitored daily for the first week
following these dosing procedures and thereafter twice during the second
week, by recording FEC, red cell packed cell volume (PCV) as well as any
changes in behavior and also weight changes. No adverse effects on
behavior, or significant differences in FEC reduction occurred between
the control and treated groups. No significant dose effect was observed
on PCV, FEC and LWT in the treated groups. The results showed that the
two plants were not efficacious against H. contortus at the dose levels
used.
Introduction
Animal health is a major constraint to livestock production in many
countries, including Kenya. Small ruminants (sheep and goats) are very
important in peri-urban situations in developing countries including
Kenya. They are easy to manage, more adaptable and provide greater
flexibility in terms of sale and purchase on an individual basis
compared to cattle. However, the greatest constraint to small ruminant
production is gastro-intestinal nematode infection. The greatest losses
associated with nematode parasite infections are sub-clinical, and
economic assessments show that financial costs of internal parasitism
are enormous (Preston & Allonby, 1979, McLeod, 1995). The conventional
method of treating animals to control nematode parasites is to use
anthelmintic drugs (dewormers). However, these modern veterinary inputs
and services are not always readily available. Sometimes they are either
too difficult to obtain or too expensive for marginal (smallholder)
farmers and pastoralists. When dewormers are available the problem is
often compounded by anthelmintic resistance (Mwamachi et al., 1995,
Waller 1997, Maingi et al., 1998) and/or poor quality drugs (Wanyangu et
al., 1996, Monteiro et al., 1998).
Under these conditions, traditional animal health care practices and
herbal remedies, referred to as ethnoveterinary medicine, provide a
readily available, low cost alternative. Through ‘trial and error,’
these products have over time become part of the traditional herbalist’s
pharmacopoeia. Amongst such products are those used for treatment of
nematode parasites in livestock. However, the purported anthelmintic
properties of the range of products available need to be scientifically
validated. Recently, a workshop was held in Kenya to compile
“Ethnoveterinary Medicine in Kenya: A field manual for traditional
animal health care practices” (Anon. 1996). The book has a section on
internal parasites and the traditional approaches to treatment. The
section describes various ways of treating stomach and intestinal worms
used by smallholder farmers and pastoralists. In this study, decoctions
of two plants Myrsine africana (Myrsinaceae) and Hagenia abyssinica
(Rosaceae) were tested in sheep to determine their anthelmintic efficacy
against the abomasal nematode Haemonchus contortus.
Materials and Methods
Animals
A total of 47 sheep were used in the trial. These were all male, Dorper
sheep 3 to 4 months of age at the time of purchase. They were moved
indoors and given a period of three weeks to get used to feeding on
pellets and hay. Within this period, the animals were dewormed with
injectable ivermectin (Ivomec®, MSD) at 200 mg/kg body weight, treated
with a long-acting tetracycline (Tenaline LA®, Sanofi) and sprayed with
flumethrin (Bayticol ®, Bayer) to remove ectoparasites according to the
manufacturers instructions.
After three weeks, the animals were each infected with 5000 L3
Haemonchus contortus larvae divided into two equal doses of 2500 L3.
Three weeks post infection, the animals were randomised into three
groups based on their FEC and LWT with 15 sheep in each group. Two
groups were treated, each with one of the two plants, while the third
served as an untreated control. In each treatment group, five animals
received the commonly reported dose rate, and half, or twice this dose.
Animals were monitored daily for the first week following these dosing
procedures and thereafter twice during the second week, by recording
FEC, red cell packed cell volume (PCV) and weight. After treatment the
animals’ feeding, behavior and activity were observed daily up to the
termination of the trial.
Plant preparation
The plants were collected from the Aberdares forest about 100 km to the
West of Nairobi. Hagenia abyssinica inflorescence was collected in
August, which was towards, the end of the flowering season for this
tree. The inflorescence flowers were cut using a professional tree
climber from Kenya Forestry Research Institute (KEFRI). Only female
inflorescence flowers (which are pink in colour) were collected. The
flowers were then plucked and kept at 4o C until used. Myrsine africana
leaves were collected in August, September and early October. This
period coincided with the start and middle of the fruiting season for
this shrub. The leaves from the shrub M. africana were plucked and kept
under similar conditions. All samples were collected between midday and
5.00 p.m. Verification of plant samples collected was carried out at the
East African Herbarium, Museum of Kenya.
Before application, the plants were removed from where they were
preserved and ground with a blender and prepared into three different
doses and applied as described in “Ethnoveterinary Medicine in Kenya: A
field manual for traditional animal health care practices” (Anon. 1996).
A day before treatment the plucked M. africana leaves were weighed into
three doses with lowest dose of 62.5 grams per animal and the highest
dose of 250 grams per lamb. The leaves were then ground with a blender
and mixed with 0.5 litres of water for the low dose per animal, 1 litre
for the medium dose and 1.5 litres of water per animal for the high
dose. The H. abyssinica flowers were also ground in a similar manner.
The lower dose composed of 15 grams, the middle 30 grams and the high 60
grams per animal. Each of the doses was mixed with 0.5 litres of water
and given to the animal without sieving. The plant preparations were
given to the animals using 300 ml soda bottles.
Statistical analysis
A least squares analysis of variance was carried out to check for
differences between groups. Faecal egg counts (FEC) were transformed
into Log10 (count). The mean weekly FEC, PCV and LWT values for were
analysed. Week one composed of the mean values for the five days samples
while week two had values for the two samplings averaged. The sample
size of 15 animals per group was chosen so as to be able to detect a FEC
reduction of 70% between the treatment groups and the control. Linear
regression analysis was carried out to check for relations in dose
levels in each treatment group, for FEC, PCV and LWT.
Results
The FEC in the two treatment groups did not decline significantly
compared to the control group (p>0.05). There was an increase in faecal
egg count within the first three days after infection but FEC declined
towards the end of the trial. However, FEC at the termination of the
experiment was higher in the H. abyssinica group than at the start of
treatment although not significantly different (Table 1). In the other
two groups there was a decline in FEC, with a higher drop in the control
group (Table 1). There was also a gradual drop in mean PCV and mean
weight from the start of experiment to the end in all groups (Fig 1 &
2). However, there were no significant differences between the treated
and control groups in PCV and weight two weeks post treatment. No
significant (p>0.05) dose effect on FEC (Tables 2), PCV, or weight was
observed in each treatment group. No abnormal behavioural changes were
observed after administration of the decoction in animals.
Table 1.
Mean weekly faecal egg count between controls and the treatment groups.
Treatment N# Log10 (FEC) ± S.E.M.(GFEC)*
Before treatment(1 sample) week1(5 samples) week2(2 samples)
Control 15(14) 4.55± 0.0735481 4.43 ± 0.1826915 4.06 ± 0.0311482
H. abyssinica 16(14) 4.45 ± 0.0728183 4.54 ± 0.0934674 4.55 ± 0.0535481
M. africana 16 4.59 ± 0.0738905 4.63 ± 0.0942658 4.21 ± 0.2416218
* GFEC = geometric mean of FEC (eggs per gram)
# (n) = Number of animals at week 2.
Table 2.
Mean weekly faecal egg count for groups treated with M. africana leaves
and H. abyssinica inflorescence decoctions
Treatment N* Log10 (FEC) ± S.E.M.(GFEC)*
Before treatment(1 sample) week1(5 samples) week2(2 samples)
Untreated Control 15 (14) 4.55 ± 0.07(35,481) 4.43 ± 0.18(26,915) 4.06 ±
0.31(11,482)
HA# Lower dose (15 gm) 5 4.52 ± 0.09(33,113) 4.68 ± 0.07(47,863) 4.58 ±
0.10(38,019)
HA Medium dose (30 gm) 5 4.50 ± 0.13(31,623) 4.45 ± 0.28(28,184) 4.55 ±
0.10(35,481)
HA High Dose (60gm) 6 (4) 4.36 ± 0.12(22,909) 4.52 ± 0.10(33,113) 4.51
± 0.12(32,359)
MA# Lower dose (62.5 gm) 5 4.68 ± 0.14(47,863) 4.57 ± 0.28(37,154) 3.80
± 0.64(6,310)
MA Medium dose (125 gm) 5 4.54 ± 0.17(34,674) 4.70 ± 0.12(50,119) 4.16 ±
0.44(14,454)
MA High Dose (250 gm) 6 4.54 ± 0.05(34,674) 4.63 ± 0.04(42,658) 4.59
± 0.04(38,905)
* (n) = Number of animals at week 2.
# MA = Myrsine africana, HA = Hagenia abyssinica
Fig 1
Mean weekly packed red cell volume (%) in control and treatment groups
post treatment.
Fig 2.
Mean weekly weight (kg) in control and treatment groups post treatment
Discussion
The current experiments assessed the efficacy of Myrsine africana and
Hagenia abyssinica as anthelmintics in sheep. The fruits of M. africana
have been reported to be used against intestinal worms (Gachathi, 1989).
Kokwaro (1993) also reported the two plants to be used against
roundworms, tapeworms and as general anthelmintics in humans and/or
livestock. In Ethiopia H. abyssinica is reputably used as a taenicide
(Desta, 1995). M. africana has also been used as an anthelmintic in
various communities in Kenya for self medication (Kokwaro, 1996). A
disalt of embelin a chemical constituent of M. africana was shown to
have some anthelmintic activity (Gupta, 1976). However the greatest
concentration of these chemicals is in the fruits with the least in the
leaves (Arot, 1994). The lower concentration of embelin in leaves may
have contributed to the lack of efficacy observed in this study.
Haemonchus contortus is the most important nematode parasite of sheep
and goats in the tropics. For any plant decoction to be of value for the
smallholder farmers, it must have activity against this parasite. It is
possible that these plants may contain chemical compounds that are
effective against tapeworms, for example Monezia spp., but not against
parasitic nematodes such as H. contortus. On the other hand, it is also
possible that plants have been considered to be efficacious against
“worms”, following their apparent observation in faeces of animals
after they were administered with a plant preparation. In sheep,
therefore, the sighting of Monezia spp. proglottids in faeces, which
could occur for several other reasons, might in some instances serve as
the simple explanation why some plants are considered as being
efficacious against worms. This could of course be tested in an
experimental situation but it is more difficult when the life cycle of
the parasite is indirect as in the case of tapeworms.
One other possible reason for a failure to obtain a response in this
study is that the recommended dose described in Anon. (1996), was not be
accurate. This was the reason why three dose levels were chosen for each
plant preparation. It was also hoped that dose-responses would have
occurred. An indication that the dose rate was inappropriate is provided
by the studies by Low et al., (1985), who demonstrated that repeated
feeding of embelin and H. abyssinica in high doses in chicks resulted in
retinal pathology and defects in visual behaviour. In this study no
signs of toxicity were observed, which were somewhat surprising
particularly at the high dose rates. In the present study the plants
were stored for a period of approximately one month. Pastoralist and
smallholders may utilize fresh plant material. This may have had an
effect on the activity of the plants.
While preparing the plants for dosing, large amounts of the plant
material were required. This would have serious consequences on the
naturally occurring stands of these plants in the locations where they
grow, should they be proven to be effective as anthelmintics. To
safeguard these plants, a policy aimed at conserving such plant
resources would need to be put in place. Although no efficacy was
demonstrated at the dose levels used and according to the sampling
conditions in this study, it would be worthwhile to repeat the present
experiments but with the ‘expert’ input from the traditional healers
about how they collect the plants and prepare the concoctions. This may
help ascertain whether there are very important, but subtle,
differences in the way in which these plant materials should be prepared
and thus their usefulness as dewormers.
In conclusion, no anthelmintic activity of the two plants was observed,
at the dose rates used. However, given that leaves and not fruits of M.
africana were used in this study, and the doses used showed no adverse
effects on the animals, there is a need to repeat the trial using higher
doses and better sampling techniques with the help of the traditional
healers.
Acknowledgement
The East Africa Herbarium and N. Gachathi a botanist at KEFRI are
thanked for helping in collection and identification of the plants. This
work is being financially supported by the Swedish International
Development Cooperation Agency (Sida/SAREC).
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