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Prevalence of Bovine Fasciolosis, Amplitude of Liver Condemnation and Its Economic Impact in Municipal Abattoir of Mekelle, Ethiopia

bovine fasciolosis
Vol 2(2), 196-205
DOI- http://dx.doi.org/10.5455/ijlr.20120616061138

A study was carried out to determine the prevalence, the amplitude of liver condemnation, and to estimate the economic impact of bovine fasciolosis at Mekelle Municipal Abattoir. Out of 1000 cattle examined, 352 (35.2%) were found positive for fasciolosis. Based on severity of tissue damage, lightly affected liver constituted 22.7% followed by moderately affected (33.5%) and severely affected (43.7%). The fluke count made on 50% of examined livers, a minimum of 2 and a maximum of 193 flukes with an overall mean load of 62 flukes per infected liver could be observed. There was a strong relationship between body condition and fluke burden. Less fluke burden (Mean = 73) in severely-affected liver and higher in moderately affected livers (Mean = 91) was detected. The species identified in 352 livers revealed the presence of Fasciola hepatica, F. gigantica, mixed infection by both species and immature fluke in 52%, 21.9%, 14.5% and 11.6%, respectively. Fasciolosis is of significant economic importance as the liver condemnations caused an average loss of US$ 2245 per annum. Hence, this disease deserves serious attention by the various stakeholders in order to improve livestock productivity of the study area in particular and the country at large. Finally, changing the livestock production system and strategic application of safe and effective anthelmentics were recommended.


Keywords : Abattoir Fasciolosis Fasciola gigantica Fasciola hepatica Liver condemnation Mekelle

Introduction

Fasciolosis is a cosmopolitant disease but its occurrence being dependent on the presence of biotypes suitable for the parasites as well as the snail intermediate host. Both Fasciola hepatica and F. gigantica are the two liver flukes commonly reported to cause fasciolosis in cattle. The life cycle of these flukes involves an intermediate host snail (Soulsby, 1986). In Ethiopia, F.hepatica is wide spread in area with altitude above 1800 to 2600 meter above sea level while F.gigantica appears to be the most common in areas below 1200 meters above sea level. Both species co-exits in area with altitude ranging between 1200 to 1800 meters above sea level.

So far, little information is available on the magnitude of fasciolosis in this region. This study therefore, aimed to determine the prevalence of the disease and its economic impact associated to liver condemnation in Mekelle Municipal Abattoir, and also to compare the intensity of infection with gross liver damage and identify the commonly involved fluke species.

Materials and Methods

Study Area and Animals

The study was conducted from November 2007 to March 2008 at Municipital Abattior, Mekelle, located about 783 km North of Addis Ababa. Purposefully, cattle were selected by age, body condition, and area of origin. In all, 1000 local Zebu cattle were examined following the antemortem and postmortem meat inspection to determine the impact of these factors on the disease.   

Study Methodology

Antemortem inspection was made on selected animals based on origin, age, and body condition and fecal examination was done on 20 % of the selected animals randomly and registered for further comparison during postmortem examination. During every visit, each animals was identified based on its body tagged before slaughter and assessment of body condition was carried out using a modified method described by Heinonen (1989). Accordingly, animals with body condition scored poor as 1, medium as 2, and good as 3. The animals examined was also grouped into two age group <5 and >5 years by dentition according to the modified procedure mentioned by De – Lahunta and Hable (1986).

During postmortem examination of the liver, flukes were collected in universal bottles and then examined to identify Fasciola species. Species identification was made using criterion mentioned by Soulsby (1986). To count the number of flukes, livers were purposively selected by intensity of tissue damage viz lightly, moderately, and severely affected; and counting was done by slicing the liver into 1.5 cm pieces, immersing in saline water and then squeezing to remove the fluke from the bile ducts. The fluid containing the flukes was sieved by mesh wire and counted.

 

 

Gross Liver Lesion

The gross lesion encountered on the infected liver was recorded as light, moderate and severely depending on severity of lesion described by Ogunrinade and Adegoke, (1982). Accordingly, 352 affected livers were classified into three groups.

  1. Lightly affected: If quarter of the liver was affected or if one bile duct was prominently enlarged on the ventral surface of the liver.
  2. Moderately affected: If half of the organ was affected or if two or more bile passages were hyper plastic.
  3. Severely affected: If the entire organ was involved or if it was cirrhotic and triangular in outline and when the right lobe was atrophied.

Assessment of Economic Loss

The total economic loss due to fasciolosis was estimated from the summation of annual whole and partial liver condemnation (ALC) and carcass weight loss (ACW). All livers affected due to fasciolosis were not totally condemned. Partial condemnation of the liver was a common practice in the abattoir. The annual liver condemnation rate was assessed considering slaughtered animals. Annual slaughter rate was calculated from the retrospective abattoir record of the last three years while retail market price of an average sized Zebu liver was determined from the personal interview made with butcheries in Mekelle town. Information obtained was then subjected to mathematical computation using the formula set by Ogunrinade and Ogurinade (1980).

  1. Total annual liver condemnation   (ALC)  = MCS  X  MLC X I

Where   ALC   =   Annual loss from liver condemnation

MCS   =   Mean annual cattle slaughtered at Mekelle Abattoir

MLC   =   Mean cost of one liver in Mekelle town

I   =    Incidence of totally condemned liver at abattoir

  1. b) Annual partial liver condemnation (PLC)

Where:       PLC =   Annual loss from partial liver condemnation

MCS =   Mean annual cattle slaughtered at Mekelle Abattoir

½ MLC =   Mean cost of half liver in Mekelle town

I = Incidence partially condemned liver at abattoir

  1. c) Carcass weight loss due to fasciolosis: An average carcass weight loss due to bovine fasciolosis was then assessed using the following formula.

Annual loss from carcass weight loss (ACW)   =   CSR X CL X BC X I

Where:             ACW   =   Annual loss from carcass weight loss.

CRS    =   Average number of cattle slaughtered per annum at Mekelle Abattoir.

CL   =   Carcass weight loss in individual cattle due to fasciolosis

BC   =   Average price of 1kg beef in Mekelle town.

I   =   Incidence rate of fasciolosis at Mekelle Abattoir

Total annual economic loss   = a + b + c

Statistical Analysis

Descriptive statistics were computed using the Excel data spread sheet programme of computer, and incidence determination and testing the different associated factors was calculated with Stata 7.0 software. Factors that influence the incidence of fasciolosis such as age, body condition and animal origin were tested using the chi-square. The infection rate and incidence rate of fasciolosis during coprological and postmortem examination was calculated by percentage.

Results           

Prevalence of fasciolosis

Out of 1000 cattle examined, 352 cattle were found to be positive for fasciolosis during postmortem examination giving a mean incidence rate of 35.2%. Monthly variation of fasciolosis was found to be 42.5 %, 40.9 %, 31.4%, 27.5% and 26.4 % in November, December, January, February and March, respectively (Table 1).

 

Table1. Monthly variation of bovine fasciolosis in Mekelle Abattoir

Month Number  examined   Number positive Monthly distribution (%)
November 275 117 42.5
December 225 92 40.9
January 175 55 31.4
February 200 55 27.5
March 125 33 26.4
Total 1000 352 35.2

In addition, out of the 200 cattle selected for coprological examination, 49 were positive for fasciolosis with an overall prevalence of 24.5%. There was monthly variation in Fasciola egg findings, the highest (29%) in November and the lowest (16%) during March (Table 2).

Table 2:- Faecal examination of cattle during antemortem examination.

Month Number

 examined

Number

positive

Monthly distribution (%)
November 55 16 29
December 45 13 28.8
January 35 8 22.8
February 40 8 20
March 25 4 16
Total 200 49 24.5

Animals with < 5 and above 5 years of age showed an infection rate of 50.6% and 33.8%, respectively (Table 3), and infection rate was significant with P<0.05.

Table 3:- Incidence of bovine fasciolosis according to age

Age (year) Number examined Number  positive Infection rate (%)
< 5 81 41 50.6
> 5 919 311 33.8
Total 1000 352 35.2

Pearson X2 (1) = 9.185            P < 0.05

The incidence of bovine fasciolosis on the basis of body condition score was graded as 1, 2, 3, and were found to be 42.4%, 36.8%, and 21.9%, respectively (Table 4), and the rate showed significant (P < 0.05) value. So, the body condition was inversely related to infection rate.

Table 4: Incidence of fasciolosis according to body condition of animals

Body

condition

Number  examined Number  positive Infection rate (%)
Poor 144 61 42.4
Medium 696 256 36.8
Good 160 35 21.8
Total 1000 352 35.2

Pearson X2 (2) = 16.173 P< 0.05

The incidence of fasciolosis based on the animal origin was assessed, and the infection rate of disease in animals originated from highland area of the region was higher than that of lowland (Table 5).

Table5. Incidence of fasciolosis based on origin of animals.

Origin of animals Number  examined Number positive Infection rate (%)
Lowland 397 125 31.5
Highland 603 227 37.64
Total 1000 352 35.2

Pearson X2(1) = 3.9811           P<0.05 (statistically significant).

Of a total of 352 infected livers, Fasciola hepatica was most commonly encountered (52%) followed by Fasciola gigantica (21.9%). Mixed infections due to both F. hepatica and F. gigantica and immature flukes accounted 14.5% and 11.6%, respectively (Table 6).

Table 6:  Fasciola species encountered in affected livers

Species of

Fasciola

Number of livers

examined

Per cent

positive

Fasciola hepatica 183 52.0
Fasciola gigantica 77 21.9
Mixed infection 51 14.5
Immature fluke 41 11.6
Total 352 100.00

Pearson X2 (3) = 13, 1326       P< 0.05

Gross Pathological Lesion of Liver Affected By Fasciolosis

Out of 352 infected livers examined, 80, 118, and154 were found to be lightly, moderately and severely affected, respectively (Table 7).

Table7. Intensity of lesions observed in 352 infected livers

Severity of infection Number

 infected

Per cent

positive

Light 80 22.73
Moderate 118 33.52
Severe 154 43.75
Total 352 100.00

 

Tthe mean number of flukes found in moderately affected livers was higher (91) than the mean number of flukes in either severely affected (73) or lightly affected liver (23).

Table 8. Lesion classification in livers with their respective average fluke burden

Pathological

lesion in liver

Number

 affected

Average fluke

burden

Lightly affected 40 23
Moderately affected 59 91
Severely affected 77 73
Total 176 187

Economic Loss Analysis

Estimation of annual economic loss analysis due to fasciolosis at Mekelle municipal abattoir was estimated from the summation of Annual whole and partial liver condemnation (ALC) and carcass weight loss (ACW).

  1. Total Annual liver condemnation (ALC) = MCS X MLC XI

Where   ALC   =   Annual loss from liver condemnation

MCS   =   Mean annual cattle slaughtered at Mekelle Abattoir

MLC   =   Mean cost of one liver in Mekelle town

I   =    Incidence of totally condemned liver at the abattoir

ALC =    7750 X 36 X 0.272

= 75,888 ETH Birr

  1. b)  Annual Partial liver condemnation (PLC)

Where:       PLC =   Annual loss from partial liver condemnation

MCS =   Mean annual cattle slaughtered at Mekelle Abattoir

½ MLC =   Mean cost of half liver in Mekelle town

I= Incidence partially condemned liver at the abattoir

PLC= 7750 X 18 X 0.08

= 11,160 Birr

  1. Carcass weight loss due to fasciolosis (ACW): Annual economic loss due to reduction of meat production. Annual loss from carcass weight loss (ACW) =CSR X CL X BC X I

Where: ACW   =   Annual loss from carcass weight loss.

CRS    =   Average number of cattle slaughtered per annum at Mekelle Abattoir.

CL   =   Carcass weight loss in individual cattle due to fasciolosis

BC   =   Average price of 1kg beef in Mekelle town.

I =   Incidence rate of fasciolosis at Mekelle Abattoir

ACW= 7750 X 0.1 X 126 X 40 X 0.352 = 137, 491. 20

Therefore, total annual economic loss due to fasciolosis in the Mekelle Municipal Abattoir is;   a + b + c

= 75,888 + 11, 160 + 137,491.20

                    = 224,539.20 ETH Birr = (2245 USD)

Discussion

The current study revealed that fasciolosis is the most prevalent parasitic disease causing considerable direct and indirect economic losses in the study area. The parasite is primarily important for condemnation of liver and causing significant financial losses. The incidence was lower (35.2%) when compared with previous reports in different parts of Ethiopia, such as 81.6% in West Shoa (Yadeta, 1994), and 83.6% in Debere Berhane (Zerihun, 2005). This might be due to difference in climate and ecological conditions such as altitude, rainfall, and temperature and livestock management system.

During the present study, Fasciola hepatica showed higher prevalence (52%) as compared to Fasiola gigantica (21.9%). Mixed infestation by both species and immature fluke was represented by 14.5% and 11.6%, respectively. The earlier findings of Hagos (2007) in the same abattoir indicated that Fasciola hepatica was predominant species which accounted 45% followed by F. gigantica 25%, mixed infection by both species (13%) and immature fluke (27%). The origin of animal also played a significant role on disease occurrence. Out of 1000 animals examined, 603 (60.3%) were from high land, and of these, 37.6% were found affected with fasciolosis.

Statistical analysis of infection rates on the basis of age indicated significant difference (P<0.05) between the two age groups. Higher infection rate occurred in younger animals (less than 5 years old) as compared to older animals. This is in agreement with Radostitis et.al. (2000) who mentioned higher infection rate occurs in young animals.

Analysis on the incidence of fasciolosis in relation to body condition of animals showed significant difference (P<0.05) indicating an inverse relation of incidence rate with body condition score. The incidence rate was observed 42.4%, 36.8%, and 21.8% for poor, medium and good body condition of animals, respectively. The animals with poor body condition are susceptible to the infectious disease. This finding corresponds with Hagos (2007) who reported 37.7%; 33.1% and 29.1% incidence rate in poor, medium and good body condition animals, respectively.

The observations of our study showed that incidence of fasciolosis was positively correlated with rainfall and humidity. The highest incidence rate was recorded during November (42.5%) during the wet month and the lowest during March (26.4%) which is dry season. The rise in the infection rates of fasciolosis during the wet months of the year is attributed to seasonal peak of snail activity in breeding and development of the larval stage flukes with in snails.

Economic importance of bovine Fasciolosis has been the main concern of several workers in Ethiopia. Bahiru and Ephrem (1979) reported an annual loss of US$ 3.6 million per annum on national basis. It is difficult to evaluate the actual economic losses incurred due to individual parasitic disease because of the occurrence of poly-parasitism in the natural cases. However, in the present study, total annual economic loss due to bovine fasciolosis was estimated US$ 2245.39 at Municipal Abattoir, Mekelle.

It is concluded that use of anthelmentics and molluscides treatment based on adequate epidemiological information seems to be the most reliable method in the control of this parasitic disease. Emphasis is given to conduct a detailed epidemiological study on the incidence of fasciolosis taking into consideration the agro- ecological situation of the region.

Acknowledgements

Sincere thanks are due to Dr. Abreha Bisrat for his kind help at the study site and also to the staff of Mekelle Municipal Abattoir and Tigray Regional Laboratory for their esteemed cooperation during the study period.

References

Bahiru, G. and Ephrem, M. 1979. Preliminary survey of bovine fasciolosis in Ethiopia. Ethiopian Journal of Agricultural Sciences 1:13-24.

De-Lahunta A. and Hable, R.E.1986. Applied Veterinary Anatomy. W.B. Saunders Company, USA.

Hagos, A. 2007. Prevalence and economic importance of fasciolosis and hydatidosis at Mekelle Municipal Abattoir. D.V.M. Thesis, Faculty of Veterinary Medicine, Addis Ababa University,  Debre Zeit, Ethiopia.

Heinonen, M. 1989. Manual of Cattle Evaluation. Ministry of Agriculture Yearly Bulletin, Addis Ababa, Ethioipa.

Ogunrinade, A. and Adegoke G.D. 1982. Bovine fasciolosis in Nigeria. Recurrent parasitic and bacterial infection. Tropical Animal Health and Production. 14: 121-125.

Ogunrinade, A. and Ogunrinade, B.I. 1980. Economic importance of bovine Fasciolosis in Nigeria. Tropical Animal Health and Production. 12: 155-159.

Radostitis, O.M., Gay, C. C., Blood, D.C. and Hencheliff, K.W. 2000. Veterinary Medicine, 9th edition. Bailliere Tindall, London.Pp.1378-1383.

Soulsby, E.J.L. 1986. Helminthes, Arthropods and Protozoa of Domesticated Animals 7th edition Billiere Tindall, London. Pp. 40-52.

Yadeta, B. 1994. Epidemiology of bovine and ovine fasciolosis and distribution of its snail intermediate

host in Western Shoa. D.V.M. Thesis, Faculty of Veterinary Medicine, Addis Ababa University, Debre Zeit, Ethiopia.

Zerihun, A. 2005. Ruminant fasciolosis: Review of the disease and its control measures in Ethiopia. Master Thesis, Faculty of Veterinary Medicine, Addis Ababa University, Debre Zeit, Ethiopia.

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