Ethiopia has a high population of 23.6 million sheep and 23.3 million goats
but productivity is generally low due to diseases, malnutrition and other management
problems (Haileleul, 2002). Helminthosis is one of the
important parasitic diseases contributing to losses in productivity (Agyei,
2003; Odoi et al., 2007).
Worldwide, parasitic helminths are a major cause of losses in productivity
and health problems of goats and sheep and are usually associated with huge
economic losses especially in resource poor regions of the world (Cernanska
et al., 2005). Parasitic helminths also cause immunosuppression and
as a result enhance susceptibility to other diseases (Kumba
et al., 2003; Torina et al., 2004;
Githigia et al., 2005).
The problem is much more severe in tropical countries due to very favorable
environmental conditions for parasite transmission, poor nutrition of host animals
and poor sanitation in facilities where animals are housed. As a result diseases
caused by helminths remain one of the major impediments to small ruminant production
in the tropics (Maichomo et al., 2004; Kumsa
and Abebe, 2009). In the tropics, up to 95% of sheep and goats are reported
to be infected with helminths of which Haemonchus and Trichostrongylus are the
two most commonly involved genera (Opara et al.,
2005; Odoi et al., 2007; Mbuh
et al., 2008). However, the majority of the animals infected with
helminths do not show clinical signs owing to the chronic nature of the disease.
Sub-clinical helminthosis is considered the most common form of infection and
cause of economic losses.
In Ethiopia, helminthosis is responsible for 25% mortality and 3.8% weight
loss in highland sheep and causes an estimated annual loss of about 700 million
Ethiopian birr (Haileleul, 2002). Helminthosis is associated
with enormous losses due to condemnation of affected organs at slaughter (Kumsa
and Wossene, 2006). Several previous studies conducted in different parts
of Ethiopia have revealed that the most common genera of parasitic nematodes
of small ruminants are: Haemonchus, Trichostrongylus, Oesophagostomum, Bunostomum,
Strongyloides and Trichuris (Haileleul, 2002; Fikru
et al., 2006; Kumsa and Wossene, 2006; Bersissa
and Ajebu, 2008). However, no study has been conducted on parasitic fauna
of small ruminants in the current study area. Therefore, a study was designed
to investigate the prevalence and composition of helminths of small ruminants
in and around Bishoftu town in central Oromia Regional state in Ethiopia that
may help to devise effective control measures against the parasites of small
MATERIALS AND METHODS
Study area: The study was carried out in and around Bishoftu town in Oromia Regional state. Bishoftu is located at 47 km East of Addis Ababa at an altitude of 1900 m above sea level. Geographically Bishoftu lies at 08°44'N and 38°58'E. Bishoftu town is located on the escarpment of the Great Rift valley. The topography of the area is marked by the presence of a number of crater lakes. These lakes and the position of the town on the escarpment of the Great Rift valley influence the climate of the area and the life of the people in the vicinity. The area experiences a bimodal rainfall pattern with a short rainy season from March to May and a long rainy season from June to September. The area has a mean annual rainfall of 850 mm and a mean annual temperature of 172°C. The farmers in the area practice mixed crop-livestock type of farming. The area has large population of donkeys, horses mules, ruminants and poultry.
Study animals: The study was carried out from November 2007 to April 2008 on naturally infected sheep and goats of indigenous breeds that are kept under the traditional extensive management system. All sheep and goats were owned by smallholder resource poor farmers. In the study area, ruminants are managed by communal holding of all species such as cattle, sheep, goats and equines which graze on areas of natural pasture. A total of 222 (157 sheep and 65 goats) were examined over the study period. Study sheep and goats were categorized into two age groups as young animals of <1 year and adults of >1 year of age. Age and sex of the study sheep and goats were recorded during sampling.
Sample collection and examination: Fecal samples were collected directly
from the rectum of each study animal. The collected samples were labeled and
placed in cool boxes and transported for examination to the laboratory of parasitology
of the Faculty of Veterinary Medicine located at Bishoftu town. The presence
of ova of nematodes and oocysts of Eimeria sp. was determined by simple
flotation technique using saturated sodium chloride as the flotation solution.
A sedimentation technique similar to the method used by Kumsa
and Abebe (2009) was employed to detect the presence of the eggs of trematodes.
For the presence of larvae of lungworms a modified Baermann method previously
described by Kumsa and Abebe (2009) was used.
Coproculture and L3 identification: Positive faecal samples
for strongyle eggs from animals of the same age, sex and species were pooled
and cultured for larval identification. Approximately 5 g faeces from each study
animal were pooled for each category and incubated at 27°C for 7 days. The
L3 were recovered using the Baermann technique. Then the L3
were counted and identified using the key morphological features described by
Van Wyk et al. (2004). Where possible 100 L3
were identified per category if <100 L3 were available then all
Data analysis: Data were entered into the Microsoft Excel program and then imported into SPSS for windows (SPSS, 2002) for analysis. Analysis of basic descriptive statistics, cross-tabulations and Chi-square (χ2) test were performed using this software. The proportion of sheep and goats excreting eggs or oocysts of parasites in the faeces by month, age and sex was analyzed using Pearsons Chi-square (χ2) test. The presence of a significant difference was considered when p≤0.05.
RESULTS AND DISCUSSION
Out of the total 222 (157 sheep and 65 goats) small ruminants examined over the study period, 81.5% (181) were found to harbor one or more parasite species. One hundred and fifty six (70.2%) of the examined small ruminants were positive for helminths while 102 (49.6%) of them were positive for Eimeria oocysts.
Total 81% of the sheep and 83% (54) of the goats studied were found to harbor
one or more parasite species (Table 1). The distribution of
different classes of helminths included nematodes followed by cestodes and trematodes
in both host species. The prevalence of nematodes was significantly (p<0.05)
higher than that of cestodes, trematodes and Eimeria sp. in both host
|| Overall prevalence of helminths and Eimeria sp. in
sheep and goats in and around Bishoftu
||Prevalence of different helminths eggs in sheep and goats
of the study area
In the sheep, the genera of helminths detected were strongyle type nematodes,
Moniezia sp., Strongyloides sp., Trichuris sp., Skrjabinema
ovis, Dictyocaulus filaria and Fasciola sp. Likewise in goats,
the genera of helminths detected were strongyle type nematodes, Moniezia
sp., Strongyloides sp. and Skrijabinema ovis. Eggs of Trichuris
sp. and Fasciola sp. and larvae of lungworms were never detected in the
goats. The types of helminth parasites encountered in sheep and goats are shown
in Table 2. A significantly (p<0.05) higher prevalence
of strongyle type eggs than the other types of helminths was recorded in both
host species. A significantly higher prevalence of Moniezia sp. was observed
in the sheep (χ2 = 8.63, p = 0.003) than in the goats, in the
lambs and kids (χ2 = 8.67, p = 0.001) than in the adults and
in the males (χ2 = 10.36, p = 0.001) than in the females in
both sheep and goats (Table 3). However, statistically significant
associations were never observed (p>0.05) between the prevalence of other
parasites and these factors in either host species.
The results of coprocultures revealed the presence of Trichostrongylus/Teladorsagia sp., Haemonchus sp., Oesophagostumum, Strongyloides and Bunostomum sp. in both sheep and goats of the study area (Table 4). Irrespective of age and sex in both host sp., Trichostrongylus/Teladorsagia sp., Haemonchus sp. and Oesophagostomum sp. were identified as the most predominant genera of helminths in the study area.
The results of the faecal examination revealed a high overall prevalence (81%
in sheep and 83% in goats) of helminths in both host species during the dry
season of the year suggesting that they are a major health and productivity
problem of small ruminants in the area. This is most probably attributed to
the fact that sheep and goats of the study area are managed under an extensive
traditional system in which the animals graze on natural pasture during all
the months of the year, their nutritional status is probably inadequate and
there is a lack of modern animal health care in the study area.
||Overall prevalence of Moniezia sp. in different ages
and sexes of sheep and goats in the study area
||Overall percentage of genera of nematodes identified from
coprocultures in sheep and goats of the study area
The overall prevalence reported in the current study is comparable to the
earlier report from Ethiopia (Fikru et al., 2006)
and elsewhere in the world (Nganga et al.,
2004; Opara et al., 2005;
Waruru et al., 2005; Raza et al., 2007).
However, the overall prevalence of parasitic helminths recorded in the current
study was lower than that reported earlier 92% in sheep and goats by
Kumsa and Wossene (2006) from Ogaden region and 100% in sheep by Bersissa
and Ajebu (2008) from Hawassa and 100% in sheep by Kumsa from Hawassa and
its surroundings. The low overall prevalence recorded in the current study during
the period from November 2007 to April 2008 is attributed to unfavorable temperature
and rainfall for the survival and development of the free living stages of helminths
on pasture during the study period. Kumsa and Wossene (2006)
reported that infective larvae of nematodes of sheep failed to develop to the
L3 stage during the dry season from November to May in a tropical
environment in eastern Ethiopia. In addition, a variety of factors such as host
age, sex, breeding status, grazing habits, the level of education and economic
capacity of the farmers, the standard of management and month and season of
study can influence the prevalence of helminths (Stearet
al., 2000; Magona and Musisi, 2002; Odoi
et al., 2007). A low prevalence of parasitic helminths during the
dry season in small ruminants was also reported from other geographical areas
of Ethiopia by several previous investigators in Ethiopia (Haileleul,
2002; Fikru et al., 2006) and from other parts
of the world (Agyei, 2003; Kumba
et al., 2003; Githigia et al., 2005;
Waruru et al., 2005; Odoi
et al., 2007). The results of the faecal examination in the sheep
showed the presence of ova of strongyle type nematodes, Moniezia sp.,
Skrjabinema ovis, Strongyloides sp., Trichuris sp., larvae
of Dictyocaulus filaria and Fasciola sp., in decreasing order.
In the goats ova of the strongyle type nematodes, Moniezia sp., Strongyloides
sp. and Skrjabinema ovis were detected in decreasing order.
The helminths recorded in the study area have also been reported previously
in other areas of Ethiopia (Haileleul, 2002; Fikru
et al., 2006; Bersissa and Ajebu, 2008;
Kumsa et al., 2010; Kumsa
and Abebe, 2009) and elsewhere in the world (Agyei,
2003; Kumba et al., 2003; Cernanska
et al., 2005; Githigia et al., 2005;
Opara et al., 2005; Waruru
et al., 2005). The study showed that nematodes are the most common
helminth parasites of both sheep and goats of the study area. The results also
revealed that strongyle nematodes were identified as the most predominant helminths
in both sheep and goat hosts in the area. This finding corroborates with the
observations of Cernanska et al. (2005), Opara
et al. (2005), Raza et al. (2007),
Bersissa and Ajebu (2008) and Kumsa
et al. (2010). The absence of ova of Trichuris and Fasciola
sp. and larvae of D. filaria in the faeces of the goats may be attributed
to the variation in the feeding behavior due to a higher proportion of time
spent on grazing in sheep than in goats, enabling to the sheep to ingest the
small number of infective larvae available during the dry season as has been
reported by Raza et al. (2007). In the study
polyparasitism, manifested as >1 type of genera of helminths in the faeces
of both sheep and goat hosts of the study area was encountered as major findings.
This finding agreed with reports of previous studies conducted in Ethiopia (Haileleul,
2002; Fikru et al., 2006;
Bersissa and Ajebu, 2008; Kumsa et al., 2010)
and elsewhere in the world (Sharkhuu, 2001; Agyei,
2003; Kumba et al., 2003; Nahed-Toral
et al., 2003; Cernanska et al., 2005;
Githigia et al., 2005; Opara
et al., 2005; Waruru et al., 2005;
Wang et al., 2006). This suggests that gastroenteritis
caused by helminths is an important contributor of morbidity and loss of production
in small ruminants in the study area.
The results of the coprocultures showed the predominance of Trichostrongylus/Teladorsagia
sp., in both sheep and goats of the study area. This observation agrees with
the previous reports of Maichomo et al. (2004),
Nganga et al. (2004), Torina
et al. (2004) and Cernanska et al. (2005).
This finding contrasts with the reports of Agyei (2003),
Githigia et al. (2005), Garcia
et al. (2007), Raza et al. (2007),
Bersissa and Ajebu (2008), Kumsa
et al. (2010), Mbuh et al. (2008)
and Tariq et al. (2008) all of which reported
the predominance of Haemonchus sp. in small ruminants. This variation
might be attributed to differences in the climate, agroecology, time of study
and animal management.
In addition, it could be due to the fact that the free living stages of Trichostrongylus/
Teladorsagia sp., are more resistant to adverse environmental conditions
such as high and low temperature and humidity than those of Haemonchus
sp. as has been reported by Magona and Musisi (2002),
Agyei (2003) and Nganga et
al. (2004) who reported similar results during the dry season the year.
In agreement with the previous report of Bersissa and Ajebu
(2008) and Kumsa et al. (2010), the larvae
of Haemonchus sp., Oesophagostomum sp., Bunsotomum sp.
and Strongyloides sp., were also detected in decreasing order.
In the present study we found Strongyloides sp. and Skrjabinema ovis
while only a few of the previous studies have reported about these genera.
In the study, statistically significant variation was never observed in the
prevalence of most helminths in sheep and goats of different age and sex and
months of the study period which was most probably due to inadequate nutritional
status during the dry season as stated by Tariq et al.
(2008) and Kumsa et al. (2010).
In this study, owners of small ruminants in the study area are at a high risk of economic losses from decreased productivity of their animals as the majority of them harbored polyparasitism and because of the high pathogenecity of Haemonchus sp., especially in sheep and goats.
Thus, gastrointestinal should be considered among those diseases responsible for health and productivity problems in small ruminants. More detailed studies on helminths should be conducted to pinpoint appropriate times for strategic deworming. In addition, year round investigation is needed to know the species composition, survival strategy and ecology of the economically important parasitic nematodes of sheep and goats in the study area.