Knowledge and perception of community about causes of cattle abortion and case‐control study of brucellosis as cause of abortion in Jimma zone, Ethiopia

Abstract Background Abortion, causes by several infectious and non‐infectious factors is one of the most critical health problems of cattle in Ethiopia. Thus, this study aimed to assess knowledge and perception of the community about potential causes of abortion and case‐control study of brucellosis as a cause of abortion in cattle of study districts. Methods A cross‐sectional study was conducted between October 2016 and October 2017 in selected districts of the Jimma zone using a questionnaire survey. Based on the questionnaire survey, we also carried out a case‐control study (141 cases and 282 controls) to confirm whether the most frequently mentioned disease (brucellosis) is associated with abortion. The blood samples were collected from both cases and controls cattle groups and then serum was separated. The presence of antibody against Brucella organism in serum was first tested by Rose Bengal Plate Test (RBPT) and all RBPT positive samples were confirmed using the Complement Fixation Test (CFT). Results From a total of 180 randomly selected respondents, the majority (59.4%) of them attributed abortion to infectious diseases. Based on the questionnaire survey, brucellosis, leptospirosis and listeriosis were identified as the major infectious causes of abortion in the areas. Physical injuries, shortage of feed and toxic substances were observed as less important non‐infection causes of abortion in the study areas. This study also identified improper disposal of aborted materials and birth products, use of communal bulls, sharing communal grazing areas and water sources which favour disease transmission. Exposure to Brucella organism was higher among cases (6.4%) than controls (2.8%) with a statistically significant difference (p = 0.042). Conclusion Brucellosis is the most important infectious cause of cattle abortion in this study. Thus, important to conduct appropriate control methods and increasing public awareness of the zoonotic transmission of brucellosis are suggested. This finding also recommended the need for further study to isolate and characterise brucellosis as a cause of abortion in cattle.


INTRODUCTION
Ethiopia has paid considerable attention to improve cattle productivity (meat and milk). Breeding and health interventions are the major strategies to be employed to increase the contribution of cattle to economic growth as well as to meet the increasing local demands (Zegeye, 2003). The priority focus area of the dairy development in the country is to develop dairying at the farmer level to increase the supply of milk from smallholder dairy farms (Dessalegn et al., 2016;Tulu et al., 2018).
However, reproductive health problems are the major factor that hinders the dairy industry development in the country (Adane et al., 2014;Benti & Zewdie, 2014). Abortion and premature expulsion of the fetus is the main constraint in dairy sector development to achieve its goal (Ernest, 2009;Lobago et al., 2006;Peter, 2000).
The cause of abortion in cattle is multifactorial, which could be infectious and non-infectious agents (Hovingh, 2009 (Pal et al., 2016;Tulu et al., 2018). Non-infectious factors such as heat stress, production stress, seasonal changes, chemical poisoning, drug, hormones, nutritional deficiencies and genetic disorders have been reported in some investigations (Hansen, 2002;Regassa & Ashebir, 2016;Sani & Amanloo, 2007). Although the infectious cause of abortion is documented to be the most common cause, diagnosis of abortions a very challenging task both to the veterinarian and cattle owner. Abortion has a direct impact on the reproductive performance of cattle (De Vries, 2006;Dinka, 2013;Hossein-Zadeh, 2013).
In Ethiopia, studies have shown that abortion in cattle is the most common reproductive health problem (Benti & Zewdie, 2014;Regassa & Ashebir, 2016;Tesfaye & Shamble, 2013). Moreover, abortion results in high economic loss because of reduced milk yield, rebreeding cost and replacement costs to the owners (Carpenter et al., 2006;Peter, 2000;Thurmond et al., 2005). A prevalence as high as ranging from 2% to 29% has been reported (Eshete & Moges, 2014;Gizaw et al., 2007;Siyoum et al., 2016;Tesfaye & Shamble, 2013) in different parts of the country. There is a steady increase in abortion cases of unknown causes in the southwest part of Ethiopia in recent years. Though, no study has been done to identify the potential causes of abortion in the study areas. This study helps to implement appropriate control and prevention methods in the study areas. Therefore, the objective of this study is to assess the knowledge and perception of the community about causes of abortion and case-control study of brucellosis as the cause of abortion in cattle of Jimma zone, Ethiopia.

Description of study areas
The study was conducted in the Limu Seka and Chora Boter districts of the Jimma zone. The districts are located at an altitude of 1100-2200 m above sea level, 09 • 24′ North latitude and 37 • 56′ East longitudes. The management systems of the districts are extensive (croplivestock production) and semi-intensive (urban production) systems ( Figure 1).

Study designs and animals
Cross-sectional and case-control studies were undertaken from October 2016 until October 2017 in selected districts of the Jimma zone.
A questionnaire survey (using a structured and semi-structured set of a question) was used to investigate the potential causes of abortion. We carried out a case-control study to investigate the potential role of brucellosis, the primary disease mentioned as a cause of cattle abortion in the areas. Cows or heifers that had experienced abortion were defined as cases, whereas controls were cows or heifers from the same herd but had no record of abortion. Female cattle with the age of two years and above were included as study animals.
Cows or heifers with no history of vaccination against brucellosis were involved in the study. For this study, abortion was defined as the loss of pregnancy at a stage where the expelled fetus is of recognisable size ranging from 42 to 260 days of gestation (Peter, 2000). The Brucella organism in cattle indeed causes abortion mainly after the third trimester though it should be suspected if abortion occurs after five months (as the erythritol concentration starts rising during this time).
The definition we used is a standard definition of abortion though it is less likely that the owners' notice early cases of abortion. In our study, 'a case' is an abortion that occurred anytime between 42 and 260 days.

Sampling method and sample size determination
We conducted a multistage sampling strategy with the zone as highest and household as lowest sampling stage, district and village in between the two stages. Jimma zone was selected purposively, while districts, peasant associations (the small administrative units in the district), villages and households were selected by a simple random sampling method. Six and four peasant associations were sampled from Limu Seka and Chora Boter districts, respectively based on the number of peasant associations and cattle population. For this study, a total of 180 households were randomly selected from both districts (107 households from Limu Seka and 73 households from Chora Boter) after initially developing of sampling frame from a list of all households in each peasant association of the districts. In the case-control study, cows/heifers with a history of abortion in the herds were selected purposely based on a case book from veterinary clinics and owners' information. The required minimum sample size was calculated using (Ausvet, 2016) base on a case-control study design with a predetermined odds ratio (OR) of 3, an expected prevalence of exposure in control groups of 10%, a desired level of confidence 95%, the precision of 5% and a power of 80% (Asmare et al., 2012;Dohoo et al., 2003), thus leading to a sample size of 97 cases. With two controls selected per case, the number of controls should have been 194. The sample size was multiplied by the design effect (D) to correct the variation in design, which was calculated using this formula D = ρ (n -1) + 1, where n was an average number of cattle in the cluster (herd) (6), an intercorrelation coefficient of ρ = 0.09 was described for Brucella abortus in cattle (Otte & Gumm, 1997). The design effect (D) was 1.45 and increasing the power by using two controls per case. Thus, a minimum of 141 cases and 282 controls were selected to be enrolled in this study.

Data collection
A total of 180 cattle keepers were randomly selected and interviewed.
To get information on the potential cause of abortion, gestation stage of abortion and management of abortion. In addition, some variables such as grazing system, water source, breeding system and feeding of storage feed also recorded. The disposal of abortion and birth product also studied. The questionnaire was administered using face-to-face interviews of respondents. In the case-control study, the important information related abortion history of animals was also recorded.

Sample collection and serological tests
About 10 ml blood samples were collected from the jugular vein of each cattle by using a sterile needle and plain vacutainer tube. Identification of each cattle was labeled on corresponding vacutainer tube and

Cross-sectional study
The age of respondents ranged between 22 and 76 years with an aver- agents to a human. Thus a good proportion (66.1%) of respondents did not handle and dispose of aborted materials or birth products properly (Table 4).
Infectious agents were mentioned as the most likely cause of abortion by the majority (59.4%) of respondents in study areas (Figure 2).
Those causes of abortion were significantly associated (χ 2 = 13.87, p = 0.003) with the occurrence of abortion in cattle using the χ 2 test.
The common infectious causes of abortion in cattle were named in Afan Oromo, the local language. The respondents recognised brucel- (2.8%) were mentioned as the leading infectious diseases causing an abortion in study areas (Figure 3).

Case-control study
In this study, a total of 423 female cattle (141 cases and 282 controls) were sampled. From a total of 423 tested cattle, 4.5% and 4.1% were positive for Brucella antibody by using RBPT and CFT, respectively.
A higher seroprevalence of brucellosis was observed in cases (6.4%) than controls (2.8%). A statistically significant difference was observed between cattle abortion and seroprevalence of brucellosis (p < 0.05) in study areas (Table 5).

DISCUSSION
The average size of cows and heifers kept by the farmers was higher than the rest of the cattle classes. Ownership of cows and heifers are differed significantly (p = 0.001) between study areas. This may indicate that farmers in the study areas keep cattle mainly for milk production and heifers were used for replacement purposes. A similar finding was reported by (Berihu & Toffik, 2014;Mengistu et al., 2017) where heifer and cows dominate their herd composition followed by oxen. The oxen were important for plowing land for crop cultivation and also for threshing.
The present study indicated that abortion (31.7%) was one of the major reproductive health problems. Most respondents indicated that abortion occurred at the last stage of pregnancy in study areas. This finding concurs with the work (Benti & Zewdie, 2014;Dinka, 2013) who reported abortion as one of the major reproductive challenges in central and southern Ethiopia. Similar results have been published by (Dechicha et al., 2010), who reported abortion as one of the main constraints to cattle production in other African countries like Algeria.
The majority of this study participants responded that they did not take aborted cows to a veterinary clinic (p = 0.034). Similarly, (Ebrahim et al., 2016) reported that the majority of respondents did not take aborted animals to a veterinary clinic (82.8%) in Kersa district, southwestern Ethiopia. This indicates that abortion is common and is not considered a serious health problem by livestock producers as its effect is subtle. Most of the respondents failed to properly manage abortion products as they simply leave them on the ground or give it to dogs. This practice would favour the transmission of contagious pathogens to susceptible species of animals including human beings. This is particularly true for some hardy pathogens which survive long in the environment.
Furthermore, the lack of awareness on potential means of transmission of abortion-causing pathogens could pose a great risk of the spread of the disease to humans and animals. This finding concurs with the report of (Tolosa, 2004) and (Bashahun et al., 2015) in selected sites of the Jimma zone.
Most of the respondents bred their cattle using common bull (p = 0.001). This might increase the chance of transmission of venereal transmitted diseases that causes abortion in cattle such as trichomoniasis and some extent leptospirosis among herds (Ndengu et al., 2017). This finding agrees with previous studies (Anteneh et al., 2010;Ebrahim et al., 2016;Mengistu et al., 2017;Regassa & Ashebir, 2016) that reported most cattle producers in most parts of the country used common bulls for breeding.
Most of the respondents (66.7%) in study areas conserve feed (grass) for their cattle (p = 0.038) in their backyard. Although it is a very good strategy, this practice has its own risk as it can harbour some pathogens if it is poorly stored. One of the most important abortifacient pathogens associated with poor feed storage includes Listeria and Mycotic microorganisms (Chandranaik et al., 2014). Interestingly, farmers have explicitly described listeriosis (Dhukkuba Hokaa) (with its clinical signs and symptoms) as one of the most important causes of abortion in the study areas. Listeria abortions usually develop in the rainy season due to farmers feed stored grass to their dairy cattle. Cattle abortions due to this organism mostly occur in the last trimester of pregnancy (Yaeger & Holler, 2007). The finding concurs with (Radostits et al., 2007), who stated the listeriosis abortion is related to stored forage and silage feeding to cattle.
The majority of the respondents used common grazing land (p = 0.039) and water source (p = 0.007) for their cattle in study areas.
This could increase frequency contact between cattle at common feeding and watering points. This in turn creates a favourable condition for the transmission of infectious causes of abortion among herds. In addition, herding a large number of animals (overcrowding) could also predispose the animals to mechanical causes of abortion as mentioned by respondents (Matope et al., 2010). This finding is in line with the reported of (Ndengu et al., 2017).
The various causes of abortion (infectious diseases, mechanical or physical agents, shortage of feed and toxic agent) mentioned by respondents (p = 0.003) in study areas agrees with standard veterinary textbooks and literature (Givens, 2006;Hovingh, 2009;Ortega-Mora et al., 2007;Pal et al., 2016;Peter, 2000) that reported the occurrence of abortion in cattle could be due to nutritional deficiencies, trauma, toxicities, or infectious agents and most of the abortion in cattle caused by infectious diseases. Most of the respondents suggested that the likely infectious causes of abortion were brucellosis, leptospirosis and listeriosis.
Abortion is one of the characters of leptospirosis (Dhukkuba Hantuuta) in female cattle. Abortion usually occurs during the last trimester of pregnancy but can occur from the 4th month onwards (Radostits et al., 2007). This may be due to Leptospira organisms prefer pregnant uterus to proliferate (Yadeta et al., 2016). Similarly, leptospirosis was stated as the most important cause of abortion in cattle in Ethiopia (Yadeta et al., 2016) and elsewhere (Dechicha et al., 2010;Elelu et al., 2016;Ndengu et al., 2017). Leptospirosis has been reported also one of the five priority zoonotic diseases identified in the country (Pieracci et al., 2016).
A good proportion of the respondents indicated that abortion was followed by a retained fetal membrane. Abortion followed by a retained fetal membrane is mainly associated with brucellosis as Brucella infection is characterised primarily by a retained fetal membrane in cattle (Radostits et al., 2007). A diseased cow usually aborted between the 5th and 7th month of pregnancy. Abortion caused by brucellosis (Gatachiisaa) commonly occurs during the last trimester of pregnancy (Parthiban et al., 2015). Similar results have been reported elsewhere state that most cattle keepers knew brucellosis as a cause of abortions (Dechicha et al., 2010;Ndengu et al., 2017). Some of the respondents also mentioned that trypanosomosis (Gowwoomsaa) and FMD (Maasa) were associated with abortion in cattle. This might be due to any disease-causing high fever in cattle that can potentially cause abortion. This does not have to be a disease that affects the reproductive tract (Radostits et al., 2007).
The case-control study was carried out to verify the disease was primarily incriminated as a cause of abortion by the farmers in the study districts. A statistically significant difference (p = 0.042) was observed in the seroprevalence of brucellosis between cases and controls. This suggests that brucellosis may be associated with cattle abortion in study areas. This result confirms the idea of the farmers as they stated brucellosis (Gatachiisaa) was the most cause of cattle abortion in their areas. Even though this result differs from earlier studies (Asmare, 2014;Asmare et al., 2012;Kebede et al., 2008;Shabbir et al., 2013), they are consistent with those of (Adugna et al., 2013;Berhe et al., 2007;Derdour et al., 2017;Haileselassie et al., 2011;Tsegaye et al., 2016). The variation between results may be due to differences in agroecology, breed, management and husbandry condition in the areas.
This can also be differences between the study areas regarding conditions that could favour the transmission of the various causes of abortion (Radostits et al., 2007).

CONCLUSION
The information generated in this study provides some important insights about abortion's potential causes. Brucellosis is the most important infectious cause of cattle abortion in this study. The finding of this study indicated that Brucella seropositive status was associated with abortion in cattle. Further intervention is needed to address the risk practices like poor disposal of abortion products, lack of awareness on the causes and transmission of the abortion-causing pathogen, use of the communal bull, common water source and grazing land. Moreover, the need for implementing control measures, making the public aware of the transmission of brucellosis and further study should be conducted to isolate and characterise brucellosis as the cause of abortion in cattle.

ACKNOWLEDGMENTS
The authors would like thank the farmers who participate in this study.
They also thank to Jimma University college of Agriculture and veterinary Medicine, and Ethiopian Institute of Agricultural Research for their assistance and cooperation during this study.

ETHICS STATEMENT
All procedures were conducted according to the experiment practice and standards approved by the animals' welfare and research ethic committee at Jimma University that is following the international guidelines for animal welfare with AgVmVM/16/1 reference number.
Additionally, verbal consent was obtained from owner of the animals.
Full cooperation and voluntary participation of all participants was obtained by assuring them the confidentiality of their involvement.

CONFLICT OF INTEREST
The authors have not declared any conflict of interests.

DATA AVAILABILITY STATEMENT
The data that support the findings of this study are available from the corresponding author upon reasonable request.

PEER REVIEW
The peer review history for this article is available at https://publons.