Prevalence of Wound Myiasis in Sheep, Goat and Donkey

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Published on International Journal of Agriculture & Agribusiness
Publication Date: December, 2019

Samuel Engdaw and Kindalem Bayew
Animal Health Disease Surveillance Expert
West Belessa Wereda Livestock Resource Development and Promotion Office
Animal Health Department Head
Janamora Wereda Livestock Resource Development and Promotion Office
West Belessa, Ethiopia

Journal Full Text PDF: Prevalence of Wound Myiasis in Sheep, Goat and Donkey (Studied in Arbaya Veterinary Clinic).

Abstract
A cross sectional study was conducted in Arbaya Veterinary Clinic from May, 2019 to October, 2019 to know the prevalence of Wound Myiasis in sheep, goat and donkey. Animals which were brought to the clinic as a case were diagnosed and the case for Wound Myiasis was identified and recorded. The study was carried out on a total of 384 animals. From these 384 diagnosed animals, 103 animals with an overall prevalence of 26.8% were found with the disease Wound Myiasis. Sheep, goats and donkeys with a respective prevalence of 24.1% (36/149), 27.8 % (52/187) and 31.2% (15/48) were found infected with the disease. Age, season, management systems, body site of infection and animal species were taken as risk factors in order to assess their significance relation with the disease. From these risk factors, age, season, management systems and body site of infection with their respective p-value 0.006, 0.00, 0.03 and 0.00 were found statistically significant while animals’ species was not significantly associated (p>0.05). The prevalence of Wound Myiasis for age young, adult and old was 13.1%, 32.2% and 26.7% respectively. Management systems were found 28.4% and 14.8% prevalence respectively for extensive and semi intensive management systems. The animals’ body site of infection were found with highly occurrence rate around the vagina followed by anus, ear and tail with their respective prevalence rate of 9.6%, 8%, 5.2% and 3.9%. Season of infection was one of the major determinant factor with high prevalence rate in the month September followed by August, October, July, June and May with their prevalence rate 50.5%, 44.7%, 32.3%, 8%, 3.4% and 0% respectively. Therefore further detailed studies of the disease and its control & prevention methods are required in the area.

Keywords: Wound myiasis, Prevalence, Risk factor & Arbaya.

1. INTRODUCTION
Ethiopia is believed to have the largest livestock population in Africa. There are about 29.3 million sheep, 29.1 million goats and 7.4 million donkeys in the country and 10 million sheep, 6 million goats and 2.6 million donkeys in the region [1]. The livestock contributes about 16% of national GDP and 35.6% of agricultural GDP. It also contributes about 15% of export earnings and 30% of agricultural employment [2]. The sector also plays a vital role as a source of food income, services and foreign exchange to the country’s economy [3]. Even though the country has this large numbers of animal population, full exploitation is very low due to the constraints of disease, nutrition and poor management system [4].
Myiasis froma a Greek word myia for “fly” [5] is the infestation of vertebrate animals with dipterous fly larvae, feed on the host’s dead or living tissue, liquid substances or ingested food for a period of time [6]. Myiasis is an arthropod disease of the major health problems of animals and causes a broad range of infections depending on the location of larvae on the body of the host [7]. Its distribution is worldwide, in tropical, subtropical and warm temperate areas. So, it is a challenging disease of domestic animals in global world [8 & 9].
It is one of the major cases that were brought to Arbaya Veterinary Clinic during the study period. Soreness and laceration, breach after delivery, urine and fecal contamination, cleanliness and sanitary condition, lack of aseptic surgery are the major predisposing factors for myiasis and its infestation causes irritation, annoyance to animals, disruption of normal habits including resting, feeding and digestion which has leading role to retard growth, loss of weight and reduced milk and meat production, death etc. [10].
Therefore this study is aimed at the following objectives:
 Determining the prevalence of wound myiasis and its relation with the risk factors.
 To recommend suitable preventive and control strategy.

2. MATERIALS AND METHODS
2.1. Study Area
A cross sectional study was conducted from May, 2019 to October, 2019 in Arbaya Veterinary Clinic of West-Belessa District, Ethiopia. Arbaya is a town in North-West Ethiopia, in Central Gondar Zone Administration. It is found at a distance of 81 km from its zone city Gondar and 178 km far from its regional city Bahirdar. It has a minimum annual average temperature 13 °C and maximum average temperature 35 °C with annual rainfall range from 800 mm to 1200 mm. It is found at 1800-2100 m high above the sea level [11].

2.2. Study Animals
The study was conducted in sheep, goats and donkeys which were brought to Arbaya Veterinary Clinic as a case for diagnosis. The study animals were all local breeds with different age, species and management systems. The animal’s case histories show that these animals under extensive management systems were allowed to graze in the field freely in day light and housed during the night in poorly constructed houses.

2.3. Study Design
A cross sectional study was conducted in extensively and semi intensively managed sheep, goat and donkey for the determination of the prevalence of Wound Myiasis. Information about age, species, body site of infection and management systems of the study animals were gathered appropriately from the animal owners. The ages were determined using owners’ information and animals’ dentition pattern as described by [12 & 13.

2.4. Sample Size Determination:
The sample size required for this study was determined according to [14. Since there was no previous work done in this study area, 50% prevalence as an expected prevalence for sample size determination and 95% confidence interval with 5% desired absolute precision were considered. Hence the sample size is estimated as:
N =
N =
Using the above formula, 384 animals were required and examined.

2.5 Data Collection
The histories of the animals which were brought with different case to Arbaya Veterinary Clinic were appropriately recorded step by step and animals were diagnosed for the detection of wound myiasis and those animals with these problems were separated and recorded carefully.

2.6. Management and Analysis
The collected data were coded and entered into Microsoft Excel spread sheet and Statistical analyses was performed using SPSS version 20 software packages. Descriptive and regression analysis was made to know the Chi-square (X2), the significance of the risk factors with the occurrence of wound myiasis and the prevalence described as percentages. Chi-square test at P<0.05 was considered as significant.

3. RESULTS
384 animals (sheep, goat and donkey) which were brought to Arbaya Veterinary Clinic as a case were diagnosed and examined for the identification of wound myiasis. From these 384 diagnosed animals, 103 cases with an overall prevalence rate of 26.8% were found being infected with wound myiasis. The disease was found with the prevalence rate of 24.1%, 27.8% and 31.2% respectively for sheep, goat and donkey. The risk factors animal’s species, age, management system, season and body site of infection were taken to assess their significance relation with the disease. The logistic regression analysis indicated the presence of strong association of wound myiasis with the risk factors age, season, management systems and body site of infection in the study area with their respective p-values of 0.006, 0.00, 0.03 and 0.00.This shows age, season, management systems and body site of infection are all significantly associated with the risk of being infected with the disease, since their p-value, P<0.05. But, the risk factor animal species was not significantly associated with the occurrence of the disease with its p-value (p=0.5). Even though the animal species are not significantly associated with the disease, donkeys are more being exposed than goat and sheep with their respective prevalence rate of 31.2% (15/48), 27.8 (52/187) and 24.1% (36/149). Animals with adult age were found more exposed than old age and young age with their prevalence rate of 32.2%, 26.7% and13.1% respectively. Animals which are managed under semi intensive management systems are less likely infected than extensively managed animals with their respective prevalence rate of 14.8% and 28.4%. The animals’ body site of infection were also found with highly occurrence rate around the vagina followed by anus, ear and tail with their respective prevalence rate of 9.6%, 8%, 5.2% and 3.9%. in the month September followed by August, October, July, June and May with their prevalence rate 50.5%, 44.7%, 32.3%, 8%, 3.4% and 0% respectively. Table 1: Overall Prevalence of wound myiasis Number of animals examined Positive animals Prevalence in % 384 103 26.8 Table 2: Prevalence of wound myiasis based on animal species Animals examined Number of animals examined Positive animals Prevalence in % Sheep 149 36 24.1 Goat 187 52 27.8 Donkey 48 15 31.2 Total 384 103 26.8 Table 3: Analysis results of wound myiasis based on different risk factors Risk factors Category Animals examined by number Positive Animals Prevalence in % Chi-Square (X2 ) P-value Species Ovine 36 36 24.1 1.1 0.5 Caprine 52 52 27.8 Equine (donkey) 15 15 31.2 Age Young 76 10 13.1 10.1 0.006 Adult 192 62 32.2 Old 116 31 26.7 Management Extensive 337 96 28.4 3.8 0.03 Semi intensive 47 7 14.8 Body site of infection Vagina 384 37 9.6 45 0.00 Anus 384 31 8.0 Ear 384 20 5.2 Tail 384 15 3.9 May 43 0 0 Season June 58 2 3.4 98 0.00 July 62 5 8 August 67 30 44.7 September 89 45 50.5 October 65 21 32.3 Figure 1: Prevalence rate in relation to season

4. DISCUSSION
This study revealed that a total of 384 animals (sheep, goat and donkey) were examined during the study period of which 103 animals were affected by Wound Myiasis with an overall prevalence rate of 26.8%. This result is relatively higher than the study results of [15-18] in respective study area of Chittagong, Italy, Qassim and Riyadh Region with their respective prevalence of 5.2%, 3%, 12.5% and 2%. This study prevalence rate is also lower than the study results of [19 & 20]. This difference in prevalence may be due to the differences in the level of management, environmental condition, housing, genetics of animals and study season. The risk factor age, management systems and body site of infection which are all significantly associated (p<0.05) with the risk of being infected with the disease are in line with the study results of [15 & 17]. Species which is not significantly associated (p>0.05) with the disease occurrence rate also agrees with the study results of [17]. Donkeys are more likely exposed to the disease than goat and sheep with their respective prevalence rate of 31.2%, 27.8 and 24.1%. This high prevalence rate to donkeys may be due to the different reasons as the owner in the area does not give attention to the housing, cleansing and management systems to donkeys comparing to sheep and goats. Goats are more exposed than sheep may be due to the feeding nature of goat that exposed it to different traumatic injury on skin which makes suitable to fly to arrest on its body than sheep. Animals which were managed under semi intensive management systems are less likely infected than extensively managed animals with their respective prevalence rate of 14.8% and 28.4%. This difference may be due to animals under extensive management systems are more exposed to fly that transmit the disease than semi intensively managed animals.
Adult age animals which were found more exposed than old age and young age with their prevalence rate of 32.2%, 26.7% and13.1% respectively, agrees with the study results of [17] that reported high prevalence rate in adults (13.0%) than young aged (11.0%). This difference of high prevalence in adult and old aged animals than young might be due to young animals pass most of their time in door which decrease their exposure to the fly and young and old animals more exposed to traumatic injury at the time of fighting together and outdoor feeding systems that exposed and attract flies than young animals.
The animals’ body site of infection vagina, anus, ear and tail were found significantly associated (p<0.05) with their respective prevalence rate of 9.6%, 8%, 5.2% and 3.9%. This high prevalence around the vagina and anus is in agreement with the study of [15] that reported myiasis as it was frequently occurs at vagina and perineal region. Giangaspero et al. [16] and Farkas et al. [21] also respectively reported as they found myiatic wound on vulva & prepuce of sheep and wound myiasis on external genital organs of sheep. This high prevalence rate around the anus and vagina region might be due to the areas are mostly soiled with diarrhea that makes suitable condition to fly. Season was the major determinant factor for the disease prevalence of Wound Myiasis. The case was highly registered in the month September followed by August, October, July, June and May with the respective prevalence of 50.5%, 44.7%, 32.3%, 8%, 3.4% & 0%. This is in line with the study results of [15, 17, 19, 22 & 23] as they reported high prevalence rate in the season of warm and humid season. This might be due to the season September, August and October in the study area is hot and humid months those are suitable to fly activities that predispose the disease to occur.

5. CONCLUSIONS AND RECOMMENDATIONS
In general, this study indicated as wound myiasis is one of the major infectious disease problems of the case brought to Arbaya Veterinary Clinic in the study season. Risk factors such as age, management systems, body site of infection and species were taken for the assessment of the prevalence. This study result show high prevalence rate in animals managed extensively and in adult and old aged animals than young. High prevalence rate was also found in the season of August, September and October and the vagina and the anus were the most frequently affected areas. Further studies are required as molecular identification of species of flies and economic analysis caused by myiasis. Based on the above conclusions, the following recommendations are forwarded:  Improvement of housing and feeding management system is important  Owners should be trained to improve the management system, especially in terms of the level of nutrition and housing systems  Extensive grazing systems should be avoided  The owner should bring the animals to veterinary clinic instead of treating traditionally in house.

6. REFERENCE
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