Prevalence and associated risk factors of major sheep gastro intestinal parasites in and around Bako Town, Western Ethiopia

Ayele Gizachew, Nugusa Fikadu and Tadesse Birhanu

School of Veterinary Medicine, College of Medical and Health Sciences, Wollega University,
P.O. Box 395, Nekemte, Ethiopia.
ayale_thevet@yahoo.com

Abstract

A cross sectional study on gastrointestinal parasites of sheep was conducted from November 2013 to May 2014 in and around Bako town with the objectives to identify the major GIT parasites, their prevalence and associated risk factors. A total of 424 fecal samples were collected for qualitative fecal examination. Those samples that were positive to Strongyle egg were subjected to quantitative fecal examination.

The study found that 77.4% of the sheep were found to harbor eggs of GIT parasites. All animals irrespective of age and sex group were affected with the parasites. From examined animals, 65.3% were infected with Strongyle species, 6.1% with Strongyloides species, 7.3% with Trichuris species, 30.9% with Emeria species, 7.3% with Monezia species, 9% with Fasciola species and 3.1% with Paramphistomum species. There was no difference in prevalence of GIT parasites between sexes and age groups. Prevalence of GIT parasites, indicating shedding of parasite eggs or oocysts, was higher in sheep with poor body condition compared with those with moderate and good body condition. Counts of Strongyle eggs revealed that 29.6, 54.1 and 16.6% of the sheep were found to be lightly, moderately and massively infested, respectively.

The study showed that GIT parasites are major problems of sheep in the study area. Thus, further studies on economic losses and epidemiology of GIT parasites of sheep, cost effective strategic treatment and awareness creation to the farmers, should be instituted in the study area.

Key words: Bako town, Ethiopia, GIT Parasite, Prevalence, Sheep

Introduction

Small ruminants are mainly found in arid and semi- arid areas of sub-Saharan Africa. Compared to cattle and camels, sheep and goats contribute a larger proportion of readily available meat in the diets of pastoralists. They have been estimated to provide up to 30% of the meat and 15% of the milk supplies in sub-Saharan Africa where thrive in a wide range of ecological regions often in conditions too harsh for the beneficial rearing of cattle. Small ruminants have also been reported to survive better under drought conditions than cattle due to their low body mass and low metabolic requirements which in turn minimize their water requirements and maintenance needed in arid and semi-arid areas. The frequent droughts and large tsetse infected areas in sub-Saharan Africa requires more small ruminants in order to supplement cattle production (Wesongah et al 2003).

In Ethiopia, sheep were the second most important livestock species next to cattle and ranks second in Africa and sixth in the world in sheep population (Gizaw et al 2007). These sheep population have become adapted to a range of environments from the cool alpine climate of the mountains to the hot and arid pastoral areas of the lowlands (Mirkana 2010). There are about 25.01 million sheep in Ethiopia, out of which 99.7% is indigenous breeds (CSA 2012). Sheep play an important economic role and make a significant contribution to both domestic and export markets through provision of food (meat and milk) and non-food (manure, skin and wool) products. They also play a major role in the food security and social well-being of rural populations living under conditions of extreme poverty which is particularly the case for eastern parts of Ethiopia (Duguma et al 2010). Hence, the estimated 25.01 million of sheep provide an important contribution to the national economy (Alemayehu et al 1995).

Although sheep represent a great resource for the nation, the productivity per animal is low and therefore the rich potential from the sector is not efficiently exploited. Sheep diseases, poor management and lesser efforts provided to improve the performance of the animals are to be responsible for the reduced productivity (Ademosun 1992). In this regard, diseases due to parasites take the lion's share in limiting the productivity of these animals all over the World. This is especially true in many tropical and subtropical regions. Small ruminants under intensive and extensive production systems are susceptible to the effects of wide range of helminthes (Abebe and Esayas 1999).

Parasitic infestations in sheep are among serious problem in the developing countries, particularly where nutrition and sanitation standards are generally poor. Gastrointestinal nematode and trematode pose a serious health threat and limit the productivity due to the associated morbidity, mortality and cost of treatment and control measures (Raza et al 2010). The prevalence of helminthes of sheep results in low productivity due to stunted growth, poor weight gain and poor feed utilization (Pedreira et al 2006). Helminthiasis adversely affects ruminants, causing hematological and biochemical disturbances (Ijaz et al 2009), anorexia, weight loss, poor reproductive performance, and even death of lambs (Hussain and Usmani 2006).

Gastrointestinal parasite infections are a world-wide problem for both small- and large-scale farmers, but their impact is greater in sub-Saharan Africa in general and Ethiopia in particular due to the availability of a wide range of agro-ecological factors suitable for diversified hosts and parasite species. Economic losses are caused by gastrointestinal parasites in a variety of ways: they cause losses through lowered fertility, reduced work capacity, involuntary culling, a reduction in food intake and lower weight gains, lower milk production, treatment costs and mortality in heavily parasitized animals (Fikru et al 2006).

Review of the available literature in Ethiopia strongly suggests that helminthosis has nationwide distribution and is also considered as one of the major setbacks to livestock productivity incurring huge direct and indirect losses in the country. However, there is lack of well established data on the magnitude, distribution and predisposing factors of sheep GIT parasites in the study area. Therefore, this study was designed to identify the major GIT parasites and their prevalence and to investigate the associated risk factors.

Materials and Methods

Study area and design

A cross-sectional study design was used to determine prevalence and associated risk factors of major sheep GIT parasites. The study was conducted in seven kebeles (Smallest administrative unit) of in and around Bako town from November 2013 to March 2014. Bako town was located at 251 kilometers to the west of Addis Ababa, in Western Oromia, West Showa Zone, Bako Tibe District. The area has an elevation of 1650 metres above sea level. The climatic condition of the area was ‘Woyna Dega’. It is located at longitude of 37º 09’ E and latitude of 09^º06’ N, and an altitude of 1650 meters above sea level. The mean annual rainfall is 886.5 mm. The minimum and maximum temperature was 13.6ºC and 28.6ºC respectively, with an average of 21.2^º C. The relative humidity was 58.7% (BARC 2014).The total area of the Bako Tibe District is about 64,469 ha of land with animal population of 137,343 cattle, 12,502 sheep, 24,212 goats, 3,685 horses, 8,415 donkey, 1023 mules, 96742 poultry, 5237 feline, 4897canine and 520 porcine (BTWOARD 2012).

Study population and sample size determination

The study population comprises of herds of sheep in selected kebeles of in and around Bako town. The different variables such as body condition scores, sex and age groups were analyzed as risk factors. The sample size was determined at 95% confidence level, 5% precision and 50% expected prevalence (Thrusfield 2005).

n = [1.96²pexp (1-pexp)]/d²

= [(1.96)²0.5(1-0.5) ]/( 0.05)²

= 384

Where n= sample size required

1.96 =t he value of Z at 95% confidence interval

Pexp =e xpected prevalence

d = desired absolute precision

According to above formula, the required sample size was 384 sheep but to increase precision of the study and representativeness of the sample 424 sheep were sampled.

Sampling method

The study animals were selected with simple random sampling irrespective of their age and sex. Nearly, equal proportions of samples were collected from each site. The animal’s body condition scores, estimated age and sex were recorded. Body condition scoring of sampled animals was categorized into three scores as poor, medium and good. Age categorization into young and adult was performed as described by Gatenby (1991). Accordingly those sheep under one year were categorized as young and adults were above one year.

Study methodology

Faecal sample collection

A fresh faecal sample of approximately 10 gram was collected directly from the rectum of 424 sheep using gloved finger. Each sample was clearly labeled with animal identification, date and place of collection. The faecal samples were placed in a universal bottle, labeled and 10 % formalin was added to preserve parasite eggs. Those samples which were not examined within 24 h of arrival at laboratory were stored at +4°C and examined the next day early in the morning.

Coprological examination

The collected faecal specimens were processed and examined by direct faecal smear, floatation and sedimentation techniques for qualitative investigation of GIT eggs and oocyst following the standard procedures. Eggs of the different parasites were identified on the basis of their morphological appearance and size (Foreit 1999). Those samples found positive for strongyle by flotation were subjected to Mc master counting technique. In this study, the floatation solution used was saturated solution of sodium chloride. Based on quantitative examinations (egg per gram of faeces), the degree of infestation was categorized as light, moderate and massive. Egg counts from 50-799, 800- 1200 and over 1200 egg per gram of faeces were considered as light, moderate, and massive infestation respectively (Soulsby 1986, Hansen and Perry 1994, Urquhart et al 2007).

Data analysis

All the data that were collected were entered to an MS excel sheet and analyzed by using SPSS version 20. Descriptive statistics were used to determine the prevalence of the parasites and Chi-square test (χ2) was used to determine any association between the prevalence of GIT parasites with age, sex and body condition. In all the analyses, confidence level was held at 95% and P<0.05 was set for significance.

Results

Prevalence of major GIT parasites in sheep examined

Of the total 424 sheep examined for gastrointestinal parasite eggs and oocysts, 77.4% were found to be positive. (Table 1).  There was no  difference in prevalence of gastrointestinal parasites between sexes or among ages.  Poor body condition sheep had higher prevalence of the parasites.

Strongyle and Emeria were the prevalent species (Table 2).

Of all the sheep examined coprologically in seven kebeles, samples from Sombo Kejo showed slightly higher parasitic infestation as compared to other sites (Table 3). 

Quantitative faecal examination finding

Faecal samples that were positive to Strongyle species by qualitative floatation technique were subjected to EPG count using McMaster egg counting technique (Table 4). Accordingly, 29.6, 54.1 and 16.6% of the sheep were found to be lightly, moderately and massively infested, respectively. No difference was observed in the EPG count across sex groups. However, age and body condition scores of the animals were found to be a risk factor for infestation by Strongyle species.  Most of the infected sheep had a faecal egg count in a range of 800 to 1200 EPG, indicating a moderate degree of infestation.

Discussion

The coprological examination done for this study using different techniques revealed an overall gastro-intestinal helminthes infestation with prevalence of 77.4 % (n=424). This finding agrees with previous studies by coprological examination in some areas of Ethiopia by Moti (2008) from Welinchity, central Ethiopia and Achenef (1997) from Debre Berhan who reported prevalence of 76.3% and 79.09%, respectively. The current prevalence was slightly lower when compared to various research outputs in Ethiopia by Bikila et al (2013) in Gechi District, Southwest Ethiopia, Melkamu (1991) from four Awrajas of Eastern Shoa, Bayou (1992) from Illubabor , Yoseph (1993) from Asella, Genene (1994) from four Awrajas of Eastern Showa, Getachew (1998) from Mekele and Tefera et al (2011) in and around Bedelle who reported 84.3%, 91.4%, 90.9%, 92.2%, 93.2%, 90.2% and 91.3%, respectively. The higher prevalence observed in different parts of Ethiopia could be ascribed to over stocking, poor nutrition (starvation), poor management practice of the animals (lack of sanitation) and frequent exposure to the communal grazing lands that have been contaminated.

In this study from one host more than one type of genera of helminthes was identified. This finding is in harmony with reports of previous studies conducted in Ethiopia by Fikru et al (2006), Hailelul (2002) and Tefera et al (2011). Among the different parasites identified from the faeces of sheep, the prevalence of Strongyle species accounted for 65.3 % followed by Emeria oocyst (30.9 %),. In this study, the strongyle species were identified in general terms, since their eggs were not differentiated easily to genus level Van Wyk et al (2004). This finding is in accordance with a number of findings obtained by different researchers in which Strongyle species were dominant. Fikru et al (2006), Bikila et al (2013), Abebe and Esayas (1999) and Anene (1994) reported a high prevalence rate in Strongyle infection followed by Emeria oocyst in Western Oromia, Gechi distinct of south West Ethiopia, Eastern part of Ethiopia and South Eastern Nigeria, respectively.

The current prevalence of gastrointestinal Strongyles agrees with reports of previous studies conducted in different parts of Ethiopia by Tigist (2008), Temesgen (2008) and Ragassa et al (2006) who reported prevalence of 56.6%, 66.6% and 70.2%, respectively. The prevalence report (42.3%) by Tesfaye (1998) was slightly lower than the current finding. Abebe and Eseyas (2001) reported prevalence of 97.0% which is higher than the current finding. This difference in prevalence rate in different parts of the country might be attributed to the difference in agro ecology and variation in management practice of animals.

The prevalence of Strongloides species in the present study was 6.1 % which agrees with the report from Bedelle by Tefera et al (2011) and from Debre Zeit by Tigist (2008) who reported the prevalence of Strongloides species as 13.04% and 8.2%, respectively. This finding was lower as compared to 45.22% from Eastern part of Ethiopia by Abebe and Eseyas (2001).

The prevalence of Trichuris species was 7.3% and this finding was in line with work of Bersissa et al (2011), Tigist (2008), Temesgen (2008) and Ragassa et al (2006) with prevalence of 7.9%, 5%, 3.3%, and 4.5%, respectively. The present finding however was lower as compared to 30.3% from Eastern part of Ethiopia by Abebe and Eseyas (2001). The prevalence of coccidian parasites was 30.9 % which is in line with report from Kenya by Kanyari et al (2009) with prevalence of 35%. This finding was higher than from in and around Jimma town by Nuraddis et al (2014) with prevalence of 11.7%.

The only cestode observed was Moniezia species, with prevalence of 7.3 %, which is lower than report from eastern part of Ethiopia by Sisay et al (2008) with prevalence of 61%. The difference of the prevalence may be due to that the area was previously occupied by pastoralist and animals were very congested, which increase the transmission of the parasite. This finding was in close accordance with report from in and around Jimma town by Nuraddis et al (2014) with prevalence of 13.1%.

The present finding of Fasciola and Paramphistomum species was 9 % and 3.1%, respectively. This finding was slightly lower than in the report by Nuraddis et al (2014), describing the prevalence of Paramphistomum and Fasciola species as 22.4% and 19.6%, respectively. This finding was also lower than the report from Kenya by Kanyari et al (2009) who reported the prevalence of Fasciola and Paramphistomum species as 37% and 30%, respectively.

The present study showed no differences in the prevalence of GIT parasites between sex groups. This finding agrees with the report by Ragassa et al (2006), Assefa and Sisay (1998), Fikru et al (2006), Getachew (1998) and Ghanem et al (2009) which showed that sex of animals did not show significant association with the prevalence of GIT parasites. This finding disagrees with the work of Dagnachew et al (2011), Yoseph (2009), Bashir et al (2012), Mihreteab and Aman (2011), Desta (2013) and Lone (2011) who reported higher prevalence of GIT parasites in females than in males. These authors stated that female animals are exposed to more stress than male animals in different times such as during pregnancy and lactation which favors the egg output of parasites.

Age wise observation revealed no difference in infestation of GIT parasites. This finding agrees with reports from Gechi district of south west Ethiopia, Gambia and Semi-arid part of Kenya by Bikila et al (2013), Waruiru et al (2005) and Fritsch et al (1993) describing as GIT parasites affect both ages equally. The present finding disagrees with the finding of Fikru et al (2006), Gamble and Zajak (1992), Watson et al (1994), Colditz et al (1996), Kanyari (1991) and 1Kanyari et al (2009) that young animals are more susceptible to parasite infection than older one. The researchers justified the result that it could be because adult animals may acquire immunity to the parasite through frequent challenge and expel the ingested parasite before they establish infection. Young animals are susceptible due to immunological immaturity and immunological unresponsiveness. However, in this study the absence of significant difference in parasites infestation between ages of animals could be attributed to the small number of young animals used.

The higher parasite infestation in sheep with poor body condition score agrees with the report of Bisset et al (1986) and Diriba and Birhanu (2013) suggesting that well-fed animals develop good immunity that suppresses the fecundity of the parasites. This study also supports the report from Kenya by Kanyari et al (2009) who showed that animals with good body condition had lower prevalence of gastrointestinal parasites than those with poor body condition.

The results for relative severity of Strongyle parasitic infestation in studied animals (29.6 %, 54.1% and 16.6% were lightly, moderately and massively infested, respectively)  are in accordance with a previous study by Tefera et al (2011) in and around Bedelle, where 40.5% were lightly, 48.5% were moderately and 10.9% were massively affected. The above finding was also in line with the report of Bikila et al (2013) from Gechi distinict of south west Ethiopia with prevalence of 25.2%, 65.6% and 9.2% for light, moderate and massive infestations, respectively.

Conclusion

• Predominant GIT parasites were Strongyles and Emeria.
• All animals irrespective of age and sex group were affected with parasites.
• Body condition was a potential risk factor for the prevalence of GIT parasites.

Implications

Further studies on economic losses and epidemiology of GIT parasite sof sheep, cost effective strategic treatment and awareness creation to the farmers should be instituted in the study area.

Acknowledgements

The authors would like to thank Wollega University, School of Veterinary Medicine, Sheep owners and Bako District Administration Office for help rendered during the study period.

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Received 14 September 2014; Accepted 17 September 2014; Published 3 October 2014

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