Prevalence and distribution of tick infestation on cattle at Fitche Selale, North Shewa, Ethiopia

B Tadesse and A Sultan

School of Veterinary Medicine, Collage of Medical and Health Science, Wollega University, P.O. Box 395, Nekemte, Ethiopia
drbirhan@yahoo.com

Abstract

The study was conducted from November 2012 to May 2013 with the aim of determining the prevalence and identification of Ixodid tick species at Girar Jarso districts of Fitche Selale.

A total of 1889 adult ticks were collected from half-body region of 384 infested cattle population. Four generas and seven species of ticks were identified. Accordingly, genus Ambylomma (39.1%) was the most abundant tick followed by Rhipicephalus (25.0%); while Hyalomma (12.4%) and Boophilus (23.5%) were found to be the least prevalent tick generas at the study site. Among the species identified in the study area Ambylomma varigatum was the most common and more abundant (32.2%) followed by Boophilus decoloratus (23.5%) and the rest species which were identified were Rhipicephalus evertsi evertsi (20.6%), Rhipicephalus pulchellus (4.45%), Amblomma lipidium (6.88%), Hyalomma marginatum rufipes (7.41%) and Hyalomma trancatum (5.03%). Among the species the least abundant in terms of its prevalence was Rhipicephalus pulchellus (4.45%). Among the risk factors that were assessed in the present study, the prevalence of disease (tick infestation) significantly varies with the breed and body condition of the cattle.  The significantly higher prevalence was seen in animals with medium (44.5%) and poor body condition (29.4%) (p=0.01). There was also significant difference in the prevalence of tick infestation between the breeds (p=0.01). The local breeds were highly infested by the ticks with the prevalence of (70.8%).

The study indicated that there was high burden of ticks in the area. Thus, strategic tick control, application of acaricides aimed at reduction of ticks population and extension education for animal breeders on the problem of ticks are highly recommended.

Key words: Ambylomma, cattle, Hyalomma, Rhipicephalus, tick species

Introduction

Ethiopia is known for its livestock population which accounts first in Africa and tenth in the world and have the highest draft animal population in the continent. The site and diversity of major agro-ecological zones of the country renders suitable environment for the support of large number and class of livestock (MEDC 1998, FAO 1999).

The livestock population of Ethiopia is estimated to be about 43 million cattle, 23 million sheep, 18 million goats, 1.65 million equines and 42 million poultry. These livestock play a vital role in the farming system of the country. Available data indicated that livestock products represent 40% of agricultural output/GDP in Ethiopia (CSA 2006). Livestock also plays an important role in providing export commodities, such as meat, live animals, hides and skins to earn foreign exchange to the country. In mixing crop livestock farming system at the highlands parts of the country, livestock mainly used for drought power, milk production and as source of manure (Kidane 2001, Solomon 2005).

Even though the livestock sub sector contributes much to the national economy, its development is hampered by different constraints. The most important constraints to cattle productions are widespread endemic diseases including parasitic infestation, poor veterinary service and lack of attention from government (Solomon 2005). From health constraints livestock are highly affected by ectoparasites mainly ticks and tick borne disease which is a directly affect the socio-economic development of poor farmers in the area. Additionally the absence of well established research regarding socio-economic and public health implication of tick and tick borne disease in the farm have a negative impact on food security, animal product and byproducts (William 2001).

Ticks are obligate blood feeding ectoparasites of vertebrates particularly mammals, birds and reptiles throughout the world. Approximately 850 species have been described worldwide (William 2001). There are two well established families of ticks, the Ixodidae (hard tick) and the Argasidae (soft ticks). Both are important vectors for disease causing agents to humans and animals throughout the world. Over 79 different species of ticks are found in eastern Africa, but many of these appear to be of little or no economic importance. In Ethiopia, about 47 species of ticks are found on livestock and most of them have important as vectors and disease causing agents and also have damaging effect on skin and hide production (Anne and Conboy 2006). Ticks transmit the wide varieties of pathogens including bacteria, rickettisia, protozoa and viruses. The major cattle tick borne diseases in Ethiopia are anaplasmosis, babesoisis, cowdrosis and theileriosis (ILRI-FAO 2005).

Among the two families of ticks the most important one is the Ixodidae because of the existence of a rigid chitinous scutum for males, which covers the entire dorsal surface, but in adult female, larva, nymph it extends only for a small area which permits the abdomen to swell after feeding. Of the Ixoidae families, Dermacntor, Rhipicephalus, Heamaphysalis, Boophlius, Ambylomma, Hyalomma, and Aponommas generas have a great veterinary importance (Wall and shearer 2001).

Even though the disease challenge is ought to prevail in the area, detail species level study and associated risk factors at the selected Girar Jarso District of Fitche Selale was not studied well. Hence determination of tick species and its prevalence in the field is very critical to prevent and control tick borne disease and it is also important in order to evaluate the impact of tick on animal hide and skin which results in decrement of productivity (Coles et al 1992).  Therefore, the objectives of the present study were to determine the prevalence and distribution of tick and assess associated host risk factors at the study area.

Materials and methods

Study area

The study was conducted at Girar Jarso District in Fitche Selale, North Shewa Zone, Oromia Regional State. The district is located at located in latitude and longitude of 9.50°N 36.3°E/ 9.08°N 36.6°E approximately 114 Km North west of Addis Ababa, capital city of the country. It has 24 rural villages (community) which have a total household population of 334,124 (CSA 2007). The climate condition is conducive for both crop and livestock production. The annual average rainfall is 1800 mm and an elevation of 2,088 meters above sea level. The annual average temperature is 21°C (NMSA 2011).There are four seasons and two rainy seasons namely the kiremt and Belg. Out of the four seasons, Kermit is cooler and Bega is hotter (EPLA 2005).

Study population

The study populations were 348 selected cattle that kept under extensive production system which varies with age, sex, breeds and body condition.

Study design

A cross sectional study was conducted from November 2012 to May 2013 on cattle which are found in the study area.

Sampling and sample size determination

Simple random sampling was subjected on the study population. The total number of cattle required for the study was calculated based on the formula given by Thrusfield (2007). By rule of thumb where there is no documented information about for the prevalence of tick infestation disease in the study area, it is possible to take 50% prevalence. In this study the sample size was calculated using 50% prevalence with 5% desired level of precision and 95% of confidence interval.

n=[1.96²(p)(1-p)]/d²

Where n= sample size

            p= Expected prevalence

            d= Desired level of precision (5%)

Study methodology

Ticks were collected from half body regions of the selected cattle and their species were identified. Total tick burden was also assessed by performing tick counting.

Tick collection and preservation

Ticks were collected successfully from cattle after being restrained using strong crushes, by physical handling. The skin of each selected cattle was inspected for the presence of ticks then, ticks were manually collected by using forceps from different regions of the animals’ body. All adult ticks (both sexes) were collected in universal bottles then the collected ticks were preserved in 70% ethyl alcohol and 10% formalin, and transported to Fitche Veterinary Laboratory. The taxonomic key of Hoogstraal (1956), Walker (1974) and Kaiser (1987) were used to identify ticks species under Stereomicroscope.  

Laboratory techniques for Tick examination

First ticks were seen grossly and classified to different genera levels. Ticks were identified into their species level depending up on their morphology and identification structures they have, such as shape of scutum, leg color, body, coxae one and ventral plates. During tick identification in the laboratory the sample was put on petridish and the species were identified by examining under stereomicroscope. The additional materials used in the laboratory were props, identification key and color print picture of different tick species.   

Data analysis

The collected data from field were entered into Microsoft excel spread sheet. The data were analyzed by using Statistical Package for Social Students (SPSS) version 21. For different variables, frequency, 95% confidence interval and p-value of 5% will be used to compute the assessment the degree of association between dependent and independent

All the data that were collected are entered to MS excel sheet and analyzed by using SPSS version 20. Descriptive statistics was used to determine the tick infestation and assess any association between the tick infestations with host risk factors (sex, age, breed and body condition score). In all the analyses, confidence level was held at 95% and P<0.05 was set for significance.

Results

Prevalence and distribution of Ticks

A total of 1889 adult Ixodidae ticks were collected from half body region of 384 cattle that were sampled and found to be positive for tick infestation. In general, four Ixodidae tick genera and seven species were identified from the study area. From identified generas; Ambylomma (39.1%) was the most abundant and widely distributed genus followed by genus Rhipicephalus (25.0%). However, Hyalomma (12.4%) was found to be the least abundant genera (Table 1).

Distribution of Tick species

A. variegatum was the most abundant tick species and it represents (32.2%) of the total tick collected followed by B. decoloratus (23.5%). In contrast to this, Rhip. pulchellus (4.45%) were found to be the least abundant tick species. Male to female sex ratio for tick species of this result indicates, higher number of males for most species except B. decoloratus that can have higher ratio of female tick species (male: female ratio were 1:4.68) (Table 2).

From four generas and seven species identified in the study area and their relative infestation rate of B. decoloratus (31.3%) were more prevalent on animals of this study. However Rhip. pulchellus (9.11%) was the least tick species found on the body of animals (Table 3).

Host risk factors associated with tick infestations disease

In this study the prevalence of tick infestation in local breeds was 75.0% (n=288) and 25.0% (n=96) in cross breeds. The body condition score of the cattle population was found to be variable among tick infestation rate. Accordingly, tick prevalence of most poor body condition cattle was more than that of cattle having good body condition. On the other hand, prevalence difference between different age groups shows the presence of high prevalence of ticks in most of cattle having one to four (1-4) years of age (Table 6).

Discussion

In the present study, the overall prevalence of tick infestation at Fitche Selale was 59.4%. This finding is in agreement with Wasihun and Doda (2013) who reported 61.0% at SNNP region of Ethiopia. However, it is higher than the finding of Tiki and Addis (2011) at Holetta, central Ethiopia and that of Haile and Zeryehun (2013) from Bench Maji zone, southwest Ethiopia with overall prevalence of 25.6% and 27.3% respectively. The most abundant tick species in the study area was found to be A. variegatum (32.2%). The reason could be attributed to the fact that this species is the most widely distributed cattle tick in Ethiopia due to suitable wooded or grassy environments (Morel 1980, Pegram et al 1981).This result is slightly higher than that of Bossena and Abdu (2012) who reported 23.4% in and around Asosa and that of Tadesse et al (2011) (18.1%) in Mezan Teferi. However, Tamiru and Abebaw (2010) reported higher prevalence (48.2%) in and around Asella, South East of Ethiopia. Those variations could be due to agro-ecological differences in the study sites which may probably favors the survival of ticks, livestock management systems including the use of insecticides and other preventives measures. The other species of genus Ambylomma was A. lipidium. According to Morel (1980); this species is common but not abundant. A. lipidium (6.88%) was the least tick infestations in present study (Table 2). Likewise, from seven species identified in this report A. lipidium was found to be the fifth prevalent species (6.88%). This result slightly agrees with that of Sisay (2001) (4.27%) in and around Mekele, Northern Ethiopia. In contrast to this, Regassa (2001) reported the least prevalence (0.02%) in Borena province than this study.

B. decoloratus is one of the most important cattle ticks in Ethiopia for its parasitic effect (Morel, 1980). Accordingly, it was the second most abundant (23.5%) tick species that was identified in the study area. This finding slightly agrees with that of Belew and Mekonnen (2011) in and around Holetta and Tamiru and Abebaw (2010) in and around Asella who reported 18.1% and 15.4% tick infestation prevalence respectively. On the other hand, the finding was lower than that of Bossena and Abdu (2012) with the tick infestation of (70.3%) in and around Asossa town, western Ethiopia. On the other hand, Regassa (2001) reported a lower prevalence (1.60%) at Borena ranch. This might be due to the management differences as the ranch have had its own tick control measures on relative bases that reduces tick burden on study animals.

Rhip. evertsi evertsi was the third abundant tick species (22.4%) in the study area. The result agrees with that of Tamiru (2008) (22.0%) in Assella, Belew (1987) (26.8%) in Nekemte Awraja, and Yussen (2009) (21.5%) in Bako, western Ethiopia. However, slightly higher prevalence (29.3% and 30.5%) was reported by Belew and Mekonnen, (2011) in and around Holetta and Bossena and Abdu, (2012) in and around Asossa respectively. The reason for wide distribution of this species of ticks in different parts of the country could be related with the non apparent preference for particular altitude, rainfall zones or seasons (Pegram et al 1981).

Rhip. pulchellus species was the least prevalent ticks (4.45%) in the study area. Results reported by Nigatu and Teshome (2012) (5.30%) in Western Amhara were slightly in agreement with this study results. Conversely, Regassa (2001) in Borena province reported a much more prevalence (81.0%) than this result, which could be due to the nature of this tick species that can have an ability to confine to semi arid and low land areas (Pegram et al 1981). Borena province having low land altitude; it becomes most favorable for survival and proliferation of this species of tick.  

H. marginatum rufipes was the fourth abundant tick species with the prevalence of 7.41%. This result is higher than that of Regassa, (2001) (0.08%), Belew and Mekonnen, (2011) (1.86%), Yussen (2009) (1.20%) and that of Tamiru and Abebaw, (2010) (2.50%) in Borena province, in and around Holetta, Bako and Assella respectively. However, the current result slightly agrees with that of Nigatu and Teshome (2012) (9.80%) in western Amhara region. The other member of genus Hyalomma found in the study area was H. trancatum (5.03%) which was the second least tick species that was identified in the study area. According to the reports of Sisay (2001) on the prevalence of H. trancatum (3.23%) in and around Mekele slightly agree with the result. This might be due to similarities of the livestock production system and agro-ecology of the study areas.

Male to female ratio of identified tick species in the study indicated that, males were found to be dominant except for B. decoloratus (1:4.68). The finding agrees with that of Tamiru and Abebaw (2010) having dominant males with exception of B. decoloratus (0.4:1). The reason behind for the dominance of male than females could be due to fully engorged female tick drop off to the ground to lay eggs while male tend to remain permanently attached to the host up to several months later to continue feeding and mating with other females on the host before dropping off and hence males normally remains on the host longer than female (Solomon et al 2001).

Among the associated risk factors that was assessed in the present study, the prevalence of the disease significantly varies with the breed and body condition of the animals. The significantly higher prevalence was seen in animals with medium (44.5%) and poor body condition (9.89%) (p= 0.01). Similarly, Wasihun and Doda (2013) have reported that the proportion of tick infestation was higher in medium body conditioned (79.8%) as compared to poor body conditioned (67.9%) and good body conditioned animals (58.0%). This might be due to the fact that medium body scored animals are exposed to any kind of diseases when grazing on the field, and poor body conditioned animals were kept at home due to their inability to walk long distant areas, so they become less infested than medium sized animals but, the well fed animals were very resistant to any kind of diseases when they grazed in the field or are kept at home.

The results of the present study also showed that there was significant difference in the prevalence of tick infestation between the breeds (p=0.01). The local breeds are highly infested by the ticks with the prevalence of (70.8%). Similar study was revealed that the presence of tick infestation in local breeds were high with a prevalence of 56.9% (n=293) whilst in cross breeds, the prevalence were 30.4% (n=228) (Tiki and Addis 2011). The significant variation in tick infestation of cattle of different breeds in the present study might be attributed to differences in management systems, lack of supplementary feeding that result in low immunity to local cattle breeds, or lack of control measures against tick on local cattle breeds. Furthermore, it can be assumed that it might be due to lack of interest of farmers about local cattle as well as taking more care to cross breed than local cattle. Moreover, local breeds are kept under extensive production system as compared to cross breeds which are kept under semi-intensive farming system. This situation could be hypothesized that regular washing of barn and animal, regular treatment of animals with acaricides will reduce the susceptibility of tick infestation in semi intensive animal whereas, extensive cattle are move anywhere for grazing, so susceptibility of tick infestation is higher.

Conclusion

• In the present study, the important and abundant tick species identified in the study area were A. variegatum, B. decolaratus, Rhip. evertsi evertsi, H. marginatum rifipus, and A. lepidium. Tick burdens were lower in animals that were is good body condition compared with those in poor or medium condition.

Acknowledgements

The authors would like to thank Fitche Veterinary Laboratory staff members for their provision of necessary materials and the help rendered during the study period.

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Received 21 June 2014; Accepted 18 July 2014; Published 1 August 2014

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