Study on strongyles and parascaris parasites population in working donkeys of central Shoa, Ethiopia

G Ayele and A Dinka

Faculty of Veterinary Medicine, Addis Ababa University, P.O.Box 34, Debre Zeit, Ethiopia
ayele_thevet@yahoo.com

Abstract

A study was conducted in three selected districts of Central Shoa, Ethiopia, from November 2007 to April 2008 to determine the prevalence and burden of strongyle and parascaris population in working donkeys in Adaa, Bereh and Boset districts. A total of 246  fecal samples were collected randomly from Bereh (n=56), Boset (n=85) and Ada (n=105) for qualitative and quantitative faecal analysis.

The overall prevalence of strongyles and Parascaris equorum was 92% and 32.5%, respectively. The prevalence of strongyle was 92.5% in Bereh, 87% in Boset and 95% in Adaa. The prevalence of Parascaris equorum was 43%, 26% and 32% in Bereh, Boset and Ada, respectively. Overall, 33% of the donkeys were positive for both strongyle and Parascaris equorum. There was no statistically significant difference (P>0.05) in prevalence rate of strongyle and parascaris across the study districts. The overall mean egg per gram of feces (epg) for strongyle and Parascaris equorum was 2893 and 120, respectively. Body condition score was not found to be a good indicator of level of parasitism in working donkeys. There was statistically significance difference (P<0.05) between age groups for the prevalence and mean egg per gram of feces of parascaris infection. As donkeys get access to deworming program increases, prevalence of parasitic burden decreases.  Cultural identification of larvae revealed Strongylus vulgaris (67.5%), Strongylus edentatus (46%), Strongylus   equines (8%), Trichostronglus axei (58.5%), cyathostomes (35.8%), Strongylus westeri (35.8%) and Triodontophorus (15.8%).  Strongyle and parascaris were extensively prevalent in the study districts.  Regular dewormining by Donkey Health and Welfare Project of Faculty of Veterinary Medicine of Addis Ababa university had an impact on the prevalence of strongyle and parascaris parasites.

Key words: Donkey, Ethiopia, Parascaris equorum, prevalence, strongyles

Introduction

Ethiopia, located in Eastern Africa, is predominantly an agricultural nation. The country has diverse agro-ecological zones, which contributed to the evolution of different agricultural production systems. Animal production is practiced in all ecological zones of the country (Tegegne and Crawford 2000).

The domestic donkey (Equus asinus) belongs to the genus Equus and the family Equidae, which includes the wild asses of Africa and Asia as well as all the species of the horse and zebra. It is believed that all the domestic donkeys in the world are descended from Africa wild ass (Fielding and Krauser 1998). There are about 115.2 million domestic equids (horses, donkeys and mules) in the world of which 44.3 million are donkeys and 57.6 million are horses. With 5.2 million donkeys Ethiopia has second largest donkey population in the world and nearly 40% of Africa donkey population (FAO 2003).

Donkeys play an important role in socio-economic development by providing transportation in areas that are inaccessible by motorized vehicles or unaffordable modern form of transportation. In Ethiopia, the unsuitability of the area for motorized transportation, cost of road construction and high donkey population allow the use of these animals for transportation (Abayneh et al 2002). Donkeys have also been used in land tillage in areas where the soil is loose and assist in threshing and trampling (Abayneh et al 2002, Getachew et al 1991)

Although donkeys are often described as hardy and resistant animals, they do suffer a number of health problems (Svendsen 1986).  Parasitic diseases have an economic impact on donkey as they cause loss through lowered fertility, reduced work capacity and increased treatment cost (Krecek et al 2002). These diseases are also serious to donkey welfare, causing pain in affected animals (Fikru et al 2005). Infections of working donkeys with gastro- intestinal parasites are recorded from most countries of Africa and a few parts of Ethiopia. In Ethiopia, few studies were done in central and eastern parts of the country (Gebreab 1998, Mohammed and Teketel 1991).

The donkey health and welfare project has launched a deworming program since 1994 in selected districts of central Oromia. The project intended to know the current status of worm population in these intervention sites. Therefore, the objectives of this study were

• To determine the prevalence and worm burden of strongyle and parascaris population in working donkeys of central Shoa.

•  To assess the effect of frequency of deworming on strongyle and parascaris population of working donkeys

Materials and methods 

Study area

The study was conducted in three different agro-ecological zones, namely Adaa (mid-land), Bereh (high-land), and Boset (low-land) from November 2007 to April 2008.

Adaa

It is located at 8⁰ 7' N latitude and 39⁰E (EMPDA 1984), 45km South East of Addis Ababa. The geography of the area is marked by a number of crater lakes. The altitude rages from 1500-1800m asl and mean annual rainfall is 1115.6mm. The mean annual maximum and minimum temperatures are 30.5⁰C and 8.5⁰_C, respectively with a relative humidity of 61.3% (NMSA 1986). The total land area of the district is 161,056 hectares. The donkey population is 46,222 (MOA 2004).

Bereh

It located 44-66 km North of Addis Ababa and at an altitude range of 2300-3000m asl. The mean annual rainfall is 3000mm. The average daily maximum and minimum temperature are 28⁰C and 15⁰C, respectively (NMSA 2004). The total land coverage is 138,900 hectares. The donkey population is 24, 395 (MOA 2004).

Boset

It is located in the East Africa Rift Valley, 100 km East of Addis Ababa with an altitude of 1500 m asl. Its total land coverage is 124,160 hectares. It has annual rain fall from 400mm to 800mm and temperature of 13.6⁰ to 27.7⁰c (NMSA 2004). The donkey population is 37,181(MOA 2004).

Study animals

The study animals were donkeys in three districts of Oromia Regional State, Central Shoa, maintained under traditional small holder extensive management production system. The total number of donkeys in donkey health and welfare project sites was 107,798. All working donkeys in the donkey health and welfare project study areas were considered irrespective of age, sex, body condition score and color.  Donkeys were grouped in to three age categories. Donkeys under two years of age were classed as young, those in range of two to ten years were classed as adult and those beyond ten years were classed as old. These age classes were based on age of first work, productive age and the life span of Ethiopian donkeys (Yoseph et al 2001; Svendsen 1997). Donkeys were also grouped in to different body condition score according to Svendsen 1997.

Determination of sample size

A sample size was calculated with expected 80% prevalence and 95% confidence interval with an absolute precision of 5% according to (Thrusfield 1995). Thus,

P exp = expected prevalence

d = desired absolute precision

1.96 = constant from normal distribution at a given confidence level

Consequently, a total of 246 working donkeys were sampled, 56, 85 and 105 from Bereh, Boset and Ada, respectively.

Study design

A purposive sampling method was employed to select the three study districts (Adaa, Bereh and Boset) for logistic reasons. These districts consist of peasant associations (PAs). The study PAs were selected from each study district based on simple random sampling based on the sampling frame obtained from the districts' Agricultural Department. Systematic random sampling was employed to select donkeys for faecal sampling.

Collection and examination of fecal samples

Faecal samples were collected directly from the rectum by using rectal gloves. Each sample was labeled with animal identification, owner’s name, date and area of collection with indelible pen. Samples were kept in refrigerator at 4⁰C to be examined for coproscopy and coproculture. Zinc sulfate solution was used as flotation fluid for this study.

Mc Master method

This quantitative technique was used to determine the number of eggs or larvae per gram of feces as described by Urquhart et al 1996 and MAFF, 1979.

Fecal culture

Those samples positive to McMaster technique were subjected to fecal culture to see the strongyle larvae profile in study districts. The samples were cultured according to (MAFF 1979).

Larvae recovery and identification

Approximately 20gm moist and crumbly feces were broken up finely using spatula. Wide mounted plastic jars were filled with the feces, closed with the lid and left at room temperature for 10-20days stirring the feces each day to prevent the growth of fungi in the culture and L3 (Third stage) larvae were recovered using the Baerman technique. A drop of lugol's iodine was added to the sediment which stains the free living nematode yellow, while parasitic 3^rd stage larvae remain unstained. The larvae was then identified under low power microscopy (10x objective), based on the shape and number of gut cells, relative size of sheath tail and shape of larvae’s tail (MAFF 1979, Kaufmann 1996).

Data analysis

The collected data were entered in to the computer using Excel software. The data were in a list format, i.e., a single row for each donkey, with columns for parasites recovered, EPG and animal identifications. Data were cleared and STATA 9.2 for windows was used to analyze. In the analysis, confidence level was held at 95% and p<0.05 was set for significance.

Results  

Coproscopy

Prevalence of concurrent infection to both strongyle and Parascaris was 33%.The over all prevalence and mean egg per gram of feces of strongyle and parascaris were 92% and 32.5%, respectively. There was no statistically significance difference (P>0.05) in the prevalence of strongyles and parascaris among districts. District level prevalence determined for parascaris and strongyles are indicated in table1.

There was no statistically significance difference between age groups for the prevalence and mean egg per gram of feces of strongyles infection (Table 2).

There was statistically significance difference (P< 0.05)   ) between age groups for the prevalence and mean egg per gram of feces of parascaris infection (Table 2). Body condition score is poorly associated with the mean egg per gram of feces for both strongyle (r=0.05) and parascaris (r=0.05) infection. The overall mean egg per gram of feces (epg) for strongyle and Parascaris equorum was 2893 and 120, respectively.

Deworming frequency with ivermectin had statistically significant association with prevalence of strongyle (p=0.001) and parascaris equorum (p=0.016). The prevalence decreased as the frequency of deworming increases (strongyle: OR=0.33; parascaris equorum: OR= 0.53) (Table 3).

Differential larvae counts

Larvae were recognized and identified by their specific morphology traits according to MAFF (1979). Seven types of helminth parasitic larvae were identified namely Strongylus vulgaris, Strongylus edentatus, Strongylus equinus,T richostrongylus axei, Cyathostomes, Strongylus westeri, Triodontophoros species (Table 4).

There was statistically significant difference (P=0.05) in the recovery rate between districts (Table 4). Strongylus vulgaris, which is known for its high pathogenic effect, was 58.9%, 56.5% and 81% prevalence in Bereh, Boset and Ada respectively.

Discussion 

The prevalence of strongyle was 93% in Bereh, 87% in Boset and 95% in Adaa.  This study was comparable with results of Yoseph et al 2001, Mulate 2005, Ayele et al 2006 and Fikru et al 2005 who reported 100%, 100%, 100% and 98.2% in donkeys of Wonchi, highland of Wollo province, Dugda Bora and western high land of Oromia, respectively. Age group had no statistically significant association with the prevalence and mean egg per gram of feces of strongyles. A similar finding was reported by Ayele et al 2006. This might be attributed to increase of land cultivation which restricts donkeys on small communal grazing land allowing the animals for continuous larvae exposure to infected pasture.

Parascaris equorum was detected in 43%, 26% and 32% of the donkeys of  Bereh, Boset and Ada, respectively. This finding is also similar to the findings of Feseha 1998, Mulate 2005 and Ayele et al 2006 who reported 40%, 44 % and 50% in donkeys of Debre Zeit, South and North Wollo provinces and Dugda Bora.

Cultural identification of larvae indicated 58.9%, 56.5% and 81% recovery rate of strongyle vulgaris in Bereh, Boset and Ada, respectively. There was significance difference (P<0.05) among the three districts. Donkeys in Ada have the highest prevalence than the other two districts. Recovery rate of Strongylus vulgaris in the present study was lower than results   reported by Yoseph et al 2001 and Ayele et al 2006. This may be due to the seasonal variation between these studies where the current study included only the dry season of the year. Strongylus vulgaris is the most pathogenic parasite in equine, causing unthriftness, weakness, and increased susceptibility to other infections and even death and fatal colic could also have arisen from strongylid overload (Khallaayoune 1991).

The prevalence of Strongylus edentates was is higher in Ada (63.8%) than Bereh (32%) and Boset (32.9%).This result is in agreement with the work of Yoseph (1996). The prevalence of Cyathostomes was lower than the report of Ayele et al 2006 and Yoseph et al 2001 who reported 100% in donkeys of Dugda Bora and central Oromia. This lower recovery rate in the current study might be due to the intervention of Donkey Health and Welfare Project of Addis Ababa University Faculty of Veterinary Medicine, through regular deworming programme.

The prevalence of Trichostrongylus  axei, as determined from different ova culture was 68%, 28% and 78% in Bereh, Boset and Ada, respectively and this was statistically different(P<0.05). The larvae recovery rate of Trichostrongylus axei in Bereh and Ada was higher than the report of Yoseph et al. 2001. The prevalence of T.axei in Boset (28%) was in agreement with the study of Yoseph et al. 2001 and Desalegne 2005. Frequency of deworming had an association with the prevalence of both strongyles and parascaris equarum. Donkeys which had higher access to ivermectin had relatively lower prevalence. This reduced prevalence might be because of decreased pasture contamination among the dewormed donkeys.

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Received 23 December 2009; Accepted 15 March 2010; Published 9 December 2010

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