Major ectoparasites of small ruminants in Bench Maji Zone, southern Ethiopia

Z Tesfaheywet and H Simeon¹

College of Veterinary Medicine, Haramaya University, P.O.Box-301, Dire Dawa, Ethiopia.
tesfahiwotzerihun@yahoo.com
¹ College of Veterinary Medicine, Haramaya University, P.O.Box-138, Dire Dawa, Ethiopia

Abstract

A cross sectional study was conducted during the period 1st October 2015 to 30th April 2015, to estimate prevalence and associated factors, and to identify the ectoparasite fauna of small ruminants (sheep and goat) in Bench Maji Zone of southern Ethiopia. A total of 384 animals (144 goats and 240 sheep) of both sex (157 male and 227 female) and different age groups (385 adult and 79 young) were examined and sampled. Both physical examination and laboratory investigation were employed in the study.

The overall prevalence of ectoparasites was 35.4% (136/384), and small ruminants were infested with one or more parasites. Individual species prevalence of ectoparsites was 37.8% and 31.3% in sheep and goats respectively. The major ectoparasites identified were tick, lice and mite with prevalence of 15.4%, 14.8% and 5.2% respectively. The present study revealed the prevalence of ticks was higher in goats (22.9%) than in sheep (10.8%) while the prevalence of lice was higher in sheep (20.8%) than in goats (4.9%) (p<0.05). In the present study, overall, four genera and ten species of ectoparasites were registered. Among the tick Rhipicephalus decoloratus and Amblyoma coherence were the highest in both sheep (6.0%, 5.5%) and goats (9.0%, 8.3%), respectively. Out of the three species of lice recorded in sheep, Damalina ovis (16.7%) was the most prevalent followed by L. ovillus (1.6%). H. eurysternus was the only species of lice recorded in goats. In the present study, mites were recorded only in sheep namely Psoroptes ovis and Chorioptes ovis with prevalence of 2.1% and 1.8% respectively. The association of age, sex and body condition with the prevalence ectoparsites was also computed and revealed variable results. With the exception of A. coherence which was 7 times more prevalent in young (30.4%) than adult goats (4.1%) (p=0.00), age was not found to have significant association with the prevalence of other ectoparsites. Likewise only A. variegatum in sheep and both A. variegatum and R .decoloratus in goats were found to be very much prevalent in animals with poor body condition (p<0.05). Similarly the prevalence of D. ovis was higher in sheep with poor (27.3%) than medium body condition (p=0.00). Variable -sex was not found to have any significant association with the prevalence of ectoparasites with the exception of P. ovis which was significantly higher in male (6.7%) than in female sheep (3.7%) (p=0.01). From the finding of this work, it can be concluded that ectoparasites are prevalent in small ruminants and may contribute to the lower productivity of goats and sheep in the study area. Therefore, attention should be given on appropriate disease mitigation in order to enhance the output from these animals.

Keywords: goat, lice, mites, prevalence, sheep, ticks

Introduction

Poor health and productivity of animal due to disease is considered as the major stumbling block to the potential of ruminants in contributing to the livestock industry (Mekonen et al 2001). Despite its huge population size, Ethiopian livestock productivity remains marginal, because of the prevalence of different diseases, malnutrition, inadequate veterinary services and management constraints. The widespread occurence of ectoparasites, cause serious economic loss to small holder farmers, the tanning industry and the country as a whole through mortality of animals, decreased production, down grading and rejection of skin and hide (Tefera and Abebe 2004).

As a result of their activity ectoparasites may have a variety of direct and indirect effects on their hosts. Direct harm may be due to blood loss, myiasis, and skin inflammation, and prurites, toxic and allergic response. And indirect harms may be due to disturbance, self wounding and social nuisance (Taylor et al 2007).

Ectoparasites in animals may include tick, mite, flea, lice, etc. (Mullen and Durden 2002). Ticks affect the host species by the inflammation they cause and infection of skin, and through transmisiion of different diseases such as looping ill by I.recinus, African swine fever, Q-fever, Theileriosis, Babesiosis and Anaplassmosis (Wall and Shearer 2001). In Ethiopia tick and tick-borne disease rank third after Trypanosomiasis and endoparasitism in cousing economic loss (Yacob et al 2008a). An estimated annual loss of US$ 500,000 from hide and skin due to down grading from tick has been reported in Ethiopia (Bekele 2002). Infestation by mites result in severe dermatitis characterized by intense prurites, crusts, alopecia, excoriation and lichenification (Radostitis et al 2008). They affect the quality of hide and skin and productivity, so the economy of Ethiopian farmers at large (Kassaye and Kebede 2010). Lice also causes cutaneous and systemic effect on hosts; the cutaneous effect is prurites, alopecia, dermatitis, restlessness, annoyance. Heavy lice infestation may cause severe anemia and reduce the productivity of ruminants (Urquart et al 1996). The effect of lice was also frequently reported in Ethiopia from different sites by different studies (Bekele et al 2011; Kumssa and Bekele 2008).

Although ectoparasites exert severe effect on the health and productivity of ruminants, various skin diseases resulting from tick lice and mite infestation have been frequently reported in variuos zones of Ethiopia (Bekele, 2002; Ayele et al 2003; Yacob et al 2008a). However, currently there is a paucity of information regarding to ectoparasites of small ruminants in Bench Maji zone. Establishing ectoparasites fauna and their role as a vector agent is essential in understanding the epidemiology of such diseases and the designing of their appropriate control measure. Therefore, the present study was carried out to identify the ectoparasite fauna of the small ruminants, estimate their prevalence and quantify risk factors associated with their occurence in Bench Maji Zone of southern Ethiopia.

Materials and methods

Study area

The study was conducted on Southern Nation Nationality and People Regional State (SNNPRS), Bench Maji zone, southern Ethiopia which is located 550km south west of Addis Ababa. The total area of the SNNPRS (district) is 92165 hectare and the climatic condition is 19.3% is Highland (>2400masl), 51.6% is mid land (1500-2400masl) and 29.1% is low land (<1700masl). The average altitude of the district is ranges from 1200-2200 m.a.s.l and the district recieve annual rain fall of 1500-2000mm. The total livestock population of the district is 91336 cattle, 41353 sheep, 15828 goats, 2881 equines and 77928 poultry (MTRVL, 2008).

Study design study population

A cross-sectional study was conducted from 1st October 2015 to 30th April 2015 on 384 indigenous sheep (144) and goats (240) of different age, sex and body condition categories. Since there was no previous survey conducted in the study area the sample size was determined based on the expected prevalence rate of 50% and absolute desired precision of 5% at confidence level of 95%, and the sample size was determined to be 384 based on formula given by Thrusfield (2005). Eighty households (80) were selected randomly from which 1-5 small ruminants were sampled for the presence of ectoparasites. The selected animals were subjected to detailed examination for the presence of ectoparasites. The small ruminants were classified as young (< 2 years) and adults (≥ 2years) according to the classification method used by Gatenby (1991) and Steel (1996). Body condition score (good, medium and poor) was recorded based on the criteria set by Nicholson and Butterworth (1996).

Protocol design and method

The study animals were sampled randomly from animals that are brought for vaccination or to clinic. After restraining the animals’ ticks were collected manually, while skin scrapings from suspected cases of mange were collected and preserved in 10% formalin. 10% KOH was used on the specimen to facilitate the release of mites from scabs and crusts according to previously published procedure (Soulsby 1982). Ticks and lice were collected in 70% alcohol. Identification of the ectoparasites was done with the aid of stereo- and compound microscope using identification criteria set by Wall and Shearer (2001) and Urquhart et al (1996).

Data analysis

The data collected was coded and fed into Microsoft-Excel spread sheet and analyzed by using SPSS version 20.0. Prevalence was determined by the formula described by Thrusfield (2005) as the rate of number of infested animals and total number of animals examined at a point in time. Pearson’s chi-square (O²) test was used to evaluate the associations of different explanatory variables (age, sex and body condition score) with prevalence of ectoparasite infestation. In all analysis, P<0.05 were set to indicate significance.

Result and discussion

The present study revealed that of the 384 small ruminants studied 136 of them were infested with one or more ectoparasites which makes the overall prevalence 35.4% in the study area (Table 1). This finding was in agreement with the report of Zeryehun and Atomsa (2012) [34.1%] from South western part of Ethiopia.

Of the ectoparasites, tick (15.4%) infestation was the outstanding followed by lice (14.8%) and mite (5.20%) (Table 1). This finding was in agreement with earlier studies elsewhere (Yacob et al 2008a; Yacob et al 2008b; Amsalu 2011) who have reported the predominance of ticks.

As indicated in Table 1, the tick infestation in the present study was 15.4% which was less than the finding of Fufa et al (2012) who reported tick prevalence of 76.50 %. The lower prevalence of ticks in the present study might be due to the period of the study which was in the longer dry season. According to Shiferaw and Abebe (2006) who studied the seasonal dynamics of ticks reported that tick infestation tends to decrease during the dry season. Prevalence of ticks by animal species was 22.9.0% and 10.8% in goat and sheep respectively (p=0.00) (Table 3). These findings are in agreement with, Yacob et al (2008a) and Yacob et al (2008b) who reported prevalence ranging from 4.7% to 31.8% in sheep and from 0.0% to 18.6% in goats. Similarly, Zeryehun and Atomsa (2012) reported prevalence of 22.5% and 6.30% in sheep and goats, respectively. These prevalence variations between reports might be due to variations in agro-ecology, husbandry practices, level of management of ectoparasites infestation in the current and previous study areas.

It was also found out that infestation with one type of ectoparasite 114 (29.7%) was more common than infestation with multiple 22(5.7%) type of ectoparasite (Table 2). Similar observation was made by Bekele et al (2011).

In this study five species of ticks (A. variegatum, A .lepidium, A. gema, A. coherence, R. decoloratus) were identified in both sheep and goats (Table 3). Other studies elsewhere in the country reported similar composition of tick species in small ruminants (Sertse 2004; Abunna et al 2009, Bekele et al 2011; Zeryehun and Atomsa 2012; Jarso et al 2014).

Among the tick species identified in small ruminants, the prevalence of R. decoloratus were the highest in both sheep (6.0%) and goats (9.0%), respectively (Table 3). The predominance of Rhipicephalus species in small ruminants was also reported by Yacob et al (2008a), Dawit et al (2012), and Nateneal and Tesfaheywet (2015).

In the present study the prevalence of A. coherence was 7 times higher in young (30.4%) than adult (4.1%) (p=0.00) goats (Table 4), which contradict the finding of Endale (2006) who observed no statistical significance difference between these age groups. This discrepancy could be variation in the management of animals.

In the present study both A. variegatum and R .decoloratus in goats (Table 4) and A. variegatum in sheep (Table 5) were very much prevalent in animals with poor body condition (p<0.05). A higher prevalence of ticks in por body conditioned small ruminants has been reported fron Eastern parts of Ethiopia (Nateneal and Tesfaheywet, 2015).

The overall prevalence of lice in the present study was 14.8% (Table 1). Prevalence of lice that ranged between 6.0% and 89.5% has been reported in the country (Kassaye and Kebede, 2010, Yesehak 2000; Sertse 2004; Tadesse et al 2011). In the present study the prevalence of lice accounted 4.90% and 20.8%, in goats and sheep respectively (p=0.000). The predominance of lice in sheep was previously reported in the country (Zeryehun and Atmosa, 2012). The higher prevalence of lice in sheep might be due to the tick hair coat of sheep compared to goats which serve as a hiding place for the lice and makes the lice not to be detached from the body even during grooming.

In the present study D. ovis, L. ovilus and H. eurysternus were the two lice species identified in sheep while H. eurysternus was the only louse identified in goats (Table 3). These species of lice have been identified in small ruminants in other parts of the country (Abunna et al 2009; Bekele et al 2011; Zeryehun and Atomsa 2012). Out of the three species of lice recorded in sheep D. ovis (16.7%) was the most prevalent followed by L. ovillus (1.6%). This finding was in consistentwith other reports (Sertse 2004; Chanie et al 2010; Bekele et al 2011). However, this result is not in agreement with the study of Kassaye and Kebede (2010) that reported the dominance of L. ovilus over other species of lice. This variation might be due to climatic condition of the two study areas where in the present study (around Mizan Teferi), the weather is much wetter than the Tigray region, north Ethiopia (Kassaye and Kebede 2010)). In the present study the prevalence of D. ovis was very much higher in sheep with poor (27.3%) than medium body condition (p=0.00) (Table 6). A similar observation was made by Kassaye and Kebede (2010), in northern Ethiopia.

In the present study only sheep were found to harbor mites (P. ovis and C .ovis) with an overall prevalence of 8(2.1%) (Table 5). Kassaye and Kebede (2010) and Tesfaheywet and Misgana (2012) reported an overall prevalence of 8.11% and 4.50% in North and the North weastern part of Ethiopia, respectively. This greater variation of prevalence might be because of the ideal macro and micro environment in the two study area which favor the breeding and multiplication of mite. High temperature, humidity and sun light favor the mite infestation (Panqui, 1994). The prevalence of P. ovis in this study was significantly higher in male (6.7%) than in female (3.7%) (p=0.01) (Table 5). In the contrary, Zeryehun and Atomsa (2012) reported no significance difference in prevalence between male and female sheep implying that sex is not determinant factor in the infestation of mite.

Conclusion

Overall small ruminants in the current study area were found to be infested with diverse ectoparasite fauna suggesting that ectoparasites are among the major constraints in the small ruminant production. Although the overall prevalence of external parasites in the study area is relatively low, serious attention should be given to further reduce the burden of ectoparasites and maximize the productivity of sheep and goats. Moreover, good veterinary services and management practices should be put in place to control ectoprasite infestations. In addition further epidemiological investigations that consider different agro-ecology and management system is warranted for appropriate control of ectoparasites.

Acknowledgement

The authors would like to thank the Bench Maji Zone Veterinary for the provision of laboratory materials and consumables. Moreover all the animal owners involved in the study are duly acknowledged for their unreserved willingness and cooperation.

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Received 26 December 2015; Accepted 3 February 2016; Published 1 April 2016

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