Livestock Research for Rural Development 29 (5) 2017 Guide for preparation of papers LRRD Newsletter

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Vector identification and bovine trypanosomosis in Edja district, south Ethiopia

Melkamu Melese, Sisay Alemu, Jelalu Kemal, Yimer Muktar and Ashebr Abraha

Haramaya University College of Veterinary Medicine, P.O.Box 138, Dire Dawa, Ethiopia
ssayalemu@gmail.com

Abstract

The objective of this cross sectional study was to estimate the prevalence of trypanosomes and assess associated risk factors as well as to determine the apparent density of tsetse fly in Edja district. For the prevalence study, dark phase contrast buffy coat examination and Giemsa stained thin blood smears were used; traps were deployed for the entomological survey and apparent density of flies.

 

The entomological survey indicated that Glossina pallidipes and Glossina fusicpes were tsetse fly species caught. The apparent density of 0.64 fly/trap/day was caught from the district. Overall bovine trypanosomosis prevalence of 5.25% was recorded with prevalence of 10.7%, 2.4% and 1.6% in Bate, Degez and Wekya peasant associations, respectively. Trypanosoma congolense and Trypanosoma vivax were detected with prevalence of 71.42% and 28.57%, respectively. Sex-wise prevalence did not show significant difference (p=0.94) between female and male cattle. Although, prevalence of trypanosomosis on age was significantly (p=0.033) higher in adult than young. Of the total 400 cattle examined higher prevalence (9.26%) was observed in cattle with poor body condition followed by 4.38% in medium animals and no infection was observed in good body condition. Based on coat color, prevalence of 8.4%, 0.86% and 2.86% was recorded in black, red and mixed color, respectively. There were differences on the hematological findings of bovine trypanosomosis in anemic than normal animals. The study indicated that trypanosomosis is the major constraint of livestock production in the area that alarms for further detailed investigation.

Key Words: entomological, Glossina, hematological, prevalence, traps


Introduction

Animal trypanosomosis has a significant negative impact on economic growth in many parts of the world (Sharma et al 2013) and it is an important livestock disease in Africa which is considered as a threat to the ongoing effort on poverty alleviation in the continent (Wint et al 2010). Trypanosomosis is a complex disease caused by unicellular parasites found in the blood and other tissues of vertebrates including livestock, wild life and people. The most important trypanosome species affecting livestock in Ethiopia are Trypanosoma congolense, Trypanosoma vivax, and Trypanosoma brucei in cattle, sheep and goats, Trypanosoma evansi in camels and Trypanosoma equiperdium in horses (Abebe 2005).Trypanosomosis is a major constraint contributing to the direct and indirect economic losses to crop and livestock production (Abebe 2005). Once it is estimated that about 38% of the national cattle herd affected or at risk of trypanosomosis infection (Dagnachew1982). More than 20,000 heads die per annum, and annual loss attributed to the diseases is estimated to be over US$236million, whereas loss due to reduce meat, milk and draft power is not applicable to this figure (OAU 2002).

 

In Ethiopia, trypanosomosis is one of the most important disease limiting livestock productivity and agricultural development due to its high prevalence in the most arable and fertile land of South-west and North-west part of the country following the greater river basins of Abay, Omo, Ghibe and Baro with a high potential for agricultural development. Currently, about 220,000 km2 area is infested with tsetse flies namely Glossina pallidipes, Glossina morsitans, Glossina fuscipes, Glossina tachinoides and Glossina longipennis (MOA 1995). A large portion of the southern part of Ethiopia is currently infested by tsetse flies and livestock are therefore at risk of trypanosomosis (Kidanemariam et al 2000). Although trypanosomosis is considered as an important disease of cattle in the SNNPRS area (Terzu 2004). However, limited researches have been done in estimating the prevalence of trypanosomosis and distribution of flies in Edja district. The present study was undertaken with the main objectives of estimating the prevalence of trypanosomosis and identifying the species of trypanosomes infecting cattle and assessing risk factors of the disease in addition to evaluate the apparent density of tsetse fly as a benchmark to initiate strategic control interventions.


Materials and methods

Study area

 

The study was conducted at three purposively selected Kebeles (small administrative units) of Edja district from January to September 2015. Edja district was located in Gurage Zone, southern nation’s nationalities people’s regional state (SNNPRS) of Ethiopia, situated at 195 Km south of Addis Ababa. According to available data the mean annual rain ranges from 600-900 mm. The altitude of the district ranges from 1,100 to 1,150 meters above sea level. Climatically the district is divided in to three distinct ecological zones namely lowland (kola, 10%), midland (Woynadega, 37%) and high land (Dega, 53%).  The land is covered by different vegetation types namely savanna grass land, forest and bush land. The livestock populations that are found in Edja district include cattle, sheep, goat, horses, mule, donkey and poultry. Among these animals, cattle are the dominant species raised in the area. The cattle population in the district is estimated about 148,000 (CSA 2009).

 

Study Population

 

The study populations constituted of zebu cattle (148 male, 252 female) kept under traditional extensive husbandry system with communal grazing and watering points. The age of animals was estimated by the following description of Bitew (2011) for Zebu cattle. Conventional age categories were made as young (1-3 years), and adult (>3 years). Body condition for each cattle was recorded by classifying animals in to three groups as good, medium and poor based on Nicholson and Butterworth (1986).

 

Study design

 

Across sectional study was conducted on 400 randomly selected cattle to estimate the prevalence of bovine trypanomosis and evaluate associated risk factors of the selected animals and study sites. The sample size was determined based on the expected prevalence of 50% and absolute desired precision of 5% at 95% confidence level. The desired sample size was calculated using the standard formula described by Thrusfield (2005).

 

Study methodology

 

Entomological survey

 

For the entomological survey a total of 56 monopyramidal baited traps were deployed along Edja district in order to asses distribution and species of tsetse flies involved in transmission of trypanosomosis. All traps were baited with acetone, Octenol (1-3-Octane) and cow urine filled in separated bottles and labeled and deployed at an interval of 200 to 250 m. After 48 hrs of trap deployment, the cages were collected to identify and count captured flies. The tsetse flies were identified in species level (Leak 1999).

 

Hematological examination

 

A total of 400 blood samples were collected from the jugular vein using sterile sharp needle and kept in by a heparinized vacutainer tubes (Radwan and Madawy 2010). Dark phase contrast buffy coat examination and Giemsa stained thin blood smears were used. Then one end (the heparanized end) of capillary rubes were sealed with crystal sealant and centrifuged at 12,000 rpm for five minutes to separate the blood cells and to concentrate trypanosomes using centrifugal forces, as buffy coat. Then the PCV was determined and recorded. The capillary tubes were then broken just below buffy coat using diamond pencil and expressed on microscopic slide and covered with a coverslip. Then it was examined under 40 objective of microscope to detect the presence of the parasites. Identification was done by morphological examination of trypanosomes on Giemsa stained thin blood smears prepared from the positive animals and examined under a microscope using the oil immersion 100 objectives (Murray et al 1988).

 

Data management and analysis

 

Data on individual animals and parasitological examination results was inserted into Ms-excel spread sheet program and transferred to the SPSS soft ware version 20.0. Chi-square was employed to estimate the prevalence on sex, age, body condition, and skin color. Two sample student’s t-test was used to assess the deference in mean PCV between trypanosome positive and negative animals. The test result was considered significant when the calculated p-value was less than 0.05 at 95% confidence interval. The density of fly population was calculated by dividing the number of flies caught by the number of traps deployed and the number of days of deployment and expressed as fly/trap/day (FTD).


Results

Entomological survey result

 

Two species of Glossina (G. pallidepes and G. fusicpes) species were identified during the entomological survey. The apparent density of flies is 0.64 FTD was caught from the district. Out of total caught tsetse flies, 36.6% were male and 63.4% were female (Table 1).

Table 1. Proportion of male and female Glossina species in the study area

Study
site

No. of
trap

Collected Glossina species

G. pallidipes

G. fuscipes

Total

FTD

Male

Female

Male

Female

Bate

22

17

21

4

9

51

1.16

Degez

19

2

5

1

6

14

0.37

Wekya

15

2

3

0

1

6

0.2

Total

56

21

29

5

16

71

0.63

FTD = fly /trap/ day

Hematological result

 

Out of 400 cattle examined with a Buffy coat technique, 21 were positive for trypanosomes giving an overall prevalence of 5.25%.The highest prevalence (10.7%) was observed in Bate while the lowest 1.6% was observed in wekya PA’s. Out of these, 21 cases of trypanosome infections detected 15 (71.42%) of the infections were due to T. congolense and 6 (28.57%) due to T. vivax (Table 2).

Table 2. Parasitological prevalence of trypanosomosis detected at study locations

Sampling
sites

No of
animal tested

Total
positive

Parasitological result

Prevalence
(%)

T . congolense

T .vivax

Bate

150

16

11(68.8)

5(31.25)

10.7

Degez

125

3

2 (66.7)

1 (33.3)

2.4

Wekya

125

2

2 (100)

-

1.6

Total

400

21

15 (71.43)

6 (28.57)

5.25

The association of trypanosomes infection with different potential risk factors analyzed revealed that there was no significant association between trypanosome infection, and the sex of animals (p=0.94). The prevalence was slightly high in male (5.1%) than female cattle (5.4%). However, statistically significant association were observed between trypanosome infection and age of the animals, body condition, skin colour and altitude level. Adult animals (11.2%), poor body condition (9.26%) black colored (8.41%) than young (2.82%), medium(4.38%) and mixed skin colour (2.8%) with P-value of 0.33, 0.004 and 0.008 respectively (Table 3).

Table 3. Prevalence of trypanosomosis based on different risk factors

Risk factors

Categories

No. examined animal

No. positive animal

Prevalence

χ2

P- value

Sex

Male

158

8

5.1

0.005

0.942

Female

242

13

5.4

Total

400

21

5.25

 

Age

Young

284

8

2.82

4.54

0.033

Adult

116

13

11.2

Total

400

21

5.21

 

Body condition

Poor

162

15

9.26

11.09

0.004

Medium

138

6

4.38

Good

100

-

-

Total

400

21

5.25

 

Skin color

Black

214

18

8.41

9.659

0.008

Red

116

1

0.86

Mixed

70

2

2.86

Total

400

21

5.25

The mean PCV of parasitemic animals were lower than that of the aparasitemic ones (p=0.000) (Table 4).

Table 4. The mean PCV value of parasitemic and aparasitemic animals

Status

No.
Examined

No. Examined

Mean
PCV (%)± SD

t-test

P-value

PCV <24%

PCV > 24%

Parasitemic

21

20(95.2%)

1(3.4%)

20.67±2.87

6.76

0.000

Aparasitemic

379

250(65.7%)

129(34%)

24.84±3.46

Total

400

270(67.5%)

130(32.5%)

24.62±3.55


Discussion

In the present study, the apparent density of tsetse flies caught was 0.63 fly/trap/day. This result is lower than the finding of Endalu et al (2016) who reported 3.38 fly/trap/day in Dangur district. The low apparent density of tsetse fly by this study may be attributed to application of tsetse control measures such as target impregnated insecticides and insecticide treatment of cattle (Kumela et al 2015).

 

The result of the present study indicated that trypanosomosis is one of the health constraints in the district. Two species of trypanosomes were observed in hematological examination namely T. congolense and T. vivax with an overall prevalence of 5.25%. The finding is not in line with Abraham and Tesfaheywet (2012) who reported 27.5% in Wozeka grid in the southern part of  Arba Minch and Wondoson (1986) who reported 19.01% in Bunno district. This lower prevalence of the present study may occur due to the difference in agro ecology of the study area, prophylactic measure and differences in veterinary services employed in the area which all contribute to the low prevalence of the disease (Cherenet et al 2006).

 

In this study, T. congolense (71.43%) is predominant species detected  as compared to T.vivax. This is in agreement with the previous result of Getachew and Jebre (1996) having 66.1% prevalence in tsetse infested area of Ethiopia. The predominance of T. congolense infection in cattle may be due to the development of better immune response to T. vivax by the infected animal (leak et al 1999).

 

Prevalence of bovine trypanomosis was ranged between sex of animals and among 21 trypanosome positive animals, 5.4% of them were female and 5.1% were male animals which agree with the study of  Getachw (1993),Tefera (1994) and Adane (1995) who reports those both male and female animas were equally susceptible to the disease. This show equal exposure to the vector of the parasite (Quadeer et al 2008).The population studied based on the age indicated adult age groups of animals were highly infected by the parasite than young. This result is comparable with the previous work by Alekaw (2004) who conclude that there is difference in prevalence between age groups who observed a higher infection in adults than in young groups. This significant difference can be due to restricted grazing of young animals which tends to reduce their chance of contact with the vectors of these disease (Bizuayehu et al 2012).

 

In infection between the emaciated, poor and good body condition animals emaciated animals are more infected than other which supports the previous study of Bizuayehu et al (2012). Animals with poor body condition were more associated with the disease as compared with animals in good body condition. Comparison conducted between the different skin colours of cattle indicated that higher prevalence was observed in cattle’s having black skin colour than that of red and mixed colour. This higher prevalence in the present study observed could due to tsetse flies by nature are attracted toward a black colour so in animals having black skin colour was high prevalence of trypanosomosis (Wondewosen2012).

 

 In the present study 95% of the parasitemic cattle were anaemic. This result was in line with the previous results by Abraham and Tesfaheywet (2012) who reported85% in Arba Minch and Muturi (1999) 88.9% at Merab. Abaya and southern Ethiopia have showed parasitemic animals were found to be anaemic as compared with aparasitemic animals. Such significant difference of PCV values in infected and non-infected cattle had been reported by Marcotty et al (2008). Anemia is one of the most indicators of trypanosomosis in cattle (Stephen 1986). Cattle with PCV values less than 24% were considered anaemic (Vanden Bossche et al 2000). Therefore, trypanosomosis may be involved in adversely lowering the PCV value of infected animals (Bizuayehu et al 2012).


Conclusion


Acknowledgements

We would like to thank the Agricultural Bureau of the Edja district. Special heartfelt thanks are extended to Melkamu Million and Dawit Tesfaye for their support during the sample collection and examination. Gurage Zone Agricultural Bureau in particular is also acknowledged for its host and intellectual support for the whole project work to end up.


References

Abebe G and Jobere Y 1996 trypanosomosis a threat to cattle production to Ethiopia. Revenne Med Vet Pp:147, 897-902.

Abraham Z and Tesfaheywet Z 2012 Prevalence of Bovine Trypanosomosis in Selected District of Arba Minch, SNNPR, Southern Ethiopia. Global Veterinaria 8 (2): 168-173.

Adane M 1995 Survey on the prevalence of bovine trypanomosis in and around Bahir Dar. Dvm thesis, Addis Ababa University, Facility of Veterinary Medicine, Debre zeit, Ethiopia.

Alekaw S 2004 Epidemiological investigation of mechanically transmitted trypanosomes (Trypanosom cangolense) of domestic animals in three district bordering lake Tana, Ethiopia. MSC thises, Addis Ababa University Faculty of veterinary medicine, Debre zeit Ethiopia.

Bitew M, Amedie Y, Abebe A andTolosa T 2011 Prevalence of bovine trypanosomosis in selected areas of Jabitehenan district, west Gojjam of Amhara regional state, north western Ethiopia. African Journal of Agricultural Research 6:140-144

Bizuayehu A, Basaznew B, Tewodros F and Mersha C 2012 Bovine trypanosomosis A threat to cattle production in Chena district, Southwest Ethiopia .Open Journal of Animal Sciences 2(4): 287-291.

CSA 2009 Federal Republic of Ethiopia central statistical agency, agricultural sample survey Report on livestock and livestock characteristic bulletin 446: 39.

Cherenet T, Sani R A, Speybroeck N, Panandam J M, Nadzr S and Van den Bossche P 2006 A comparative longitudinal study of bovine trypanosomosis in tsetse-infested zones of the Amhara Region, northwest Ethiopia. Veterinary Parasitology 140: 251-258.

Dagnachew Z 1982 trypanosomosis in Ethiopia. Proceedings of the 3rdInternational Symposium on Veterinary Epidemiology and Economics Pp 485.

Endalu M, Kumela L and Delesa D 2016 Prevalence of bovine trypanosomosis and apparent density of tsetse fly in eastern part of Dangur District, north western Ethiopia. Journal of veterinary science and technology 7:4

Getachew T 1993 Prevalence of bovine trypanomosis in two districts of western Gojjam province. DVM thesis AAU, FVM, Debre zeit, Ethiopia.

Getachw A and Jober Y 1996 Trypanomosis, A threat for cattle production in Ethiopia. Revenne Med. Vet 147:897-902.

Kidanemariam  A , Hadgu K and Sahle M 2000 Study on trypanosomosis and its vectors in Humbo and Merab districts, North Omo, Ethiopia. Journal of the Ethiopian Veterinary Association 4:73-78.

Kumela L, Delesa D, Mohamed K and Teka F 2015 Prevalence of Bovine Trypanosomosis and Apparent Density of Tsetse and Other Biting Flies in Mandura District, North west Ethiopia journal of veterinary science and technology 6:3

Leak SGA 1999 Tsetse Biology and Ecology their role in the Epidemiology of Trypanosomosis. CAB International, Nairobi, Kenya. Pp 568.

Marcotty T, Simukoko H, Berkvens D, Vercruysse J, Praet N and Van den Bossche P 2008 The use of the PCV-value in the diagnosis of trypanosomal infections in cattle. Preventive Veterinary Medicine87:288-330.

MOA 1995 Federal Democratic Republic of Ethiopia, Ruminant livestock development strategy, Addis Ababa, Ethiopia. Pp 13.

Murray M, Murray P K and McIntyre,W I M 1988 An improved parasitological technique for the diagnosis of African trypanomiasis. Transaction of the Royal Society of Tropical Medicine and Hygien71: 325-326.

Muturi K 1999 Epidemiology of bovine trypanosomosis in selected sites of the Southern RiftValley of Ethiopia. M. Sc. thesis, Addis Ababa University with Freie Universitants, Berlin.

Nicholson  M J and Butterworth M H 1986 A guide to condition scoring of zebu cattle. ILCA, Addis Ababa Ethiopia pp 212-235.

OAU 2001 Trypanosomosis, Tsetse and Africa. The year book report 2001.

Quadeer M A, anbirni D S, Usman M, Akogun O B,Gundiri M A and Bobbo A G 2008 Prevalence of bovine trypanosomosis in Bassa local government area, Plateau State, Nigeria. Nigeria Journal of Parasitology29: 136-139.

Radwan R and Madawy E 2010 Diagnosis and epidemiological studies of bovine trypanosomosis in Kaliobia Governorate, American journal of science 6(11).

Sharma A, Singla LD, Ashuma, Batth BK, Kaur P, Javed M and Juyal PD 2013 Molecular prevalence of Babesia bigemina and Trypanosoma evansi in dairy animals from Punjab, India by duplex PCR: A step forward to detection and management of concurrent latent infections. Biomed Res. Int. Article ID 893862 pp. 8.

Stephen LE 1986 Trypanosomosis: A veterinary perspective. Pergamon press, Oxford. P 67.

Terzu D 2004  seasonal Dynamics of tsetse and trypanosomosis in select site of southern nation nationalitys and people reginal state (SNNPRS), Ethiopian MSCT in, hesu- Addis Ababa university faculty of veterinary medicine, Debrezite, Ethiopia. 

Tewolde N, Abebe G, Eisler M Mc, Dermott J, Greiner  M, Afework Y, Kyule, Munsterman S, Zessin K h and Clausen P H 2004 Application of field methods to assess Isometamidium resistance of trypanosomes in cattle in Western Ethiopia. Acta tropica  90:163-170.

Thrusfield M 2005 Veterinary Epidemiology, Third Edition, Blackwell Science Ltd., UK, Pp. 229-245.

Vanden Bossche P, Shumba W and Makhambera P 2000 The distribution and epidemiology of bovine trypanosomosis in Malawi. Veterinary Parasitology88: 163-176.

Wint W, Shaw A, Cecchi G, Mattioli R and Robinson T 2010 Animal trypanosomosis  and poverty in the Horn of Africa Workshop Report. IGAD Livestock Policy Initiative, July 6–7, 2010at Regional Centre for Mapping of Resources for Development (RCMRD).

Wondesen  A 1986 Testes and trypanomosis In bunno province. DVM thesis faculty of veterinary medicine, Addis Ababa university debre zeit.

Wondewosen T, Dechasa T and Anteneh W 2012 Prevalence study of bovine trypanosomosis and tsetse density in selected villages of Arbaminch Ethiopia, Journal of Veterinary Medicine and Animal Health 4(3): 36-41


Received 24 December 2016; Accepted 9 February 2017; Published 1 May 2017

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