# Seroprevalence and Risk Factors ofToxoplasma gondii Infection among Domestic Ruminants in East Hararghe Zone of Oromia Region, Ethiopia

Authors: Berhanu Tilahun; Yacob Hailu Tolossa; Getachew Tilahun; Hagos Ashenafi; Shihun Shimelis
Journal: Veterinary Medicine International
 (2018)

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## Abstract

A cross-sectional study was carried out from July 2011 to September 2013 to assess the seroprevalence and identify risk factors ofToxoplasma gondii infection in domestic ruminants of East Hararghe zone of Oromia region, Ethiopia. Sera of 1360 domestic ruminants were analyzed for the presence of anti-T. gondii IgG antibodies using the indirect enzyme-linked immunosorbent assay (iELISA). Additionally, the owners were also interviewed using a structured questionnaire to identify the potential risk factors ofT. gondii infection. Overall, the prevalence ofT. gondii infection in domestic ruminants was 22.2% (302/1360). The seroprevalence in sheep, goats, cattle, and camels was 33.7%, 27.6%, 10.7%, and 14.4%, respectively. District, species, sex, age, and water source were identified as risk factors forT. gondii infection. Increased seropositivity was observed in females (OR = 2.63) and also with the use of pond (OR = 4.25) and pipe (OR = 9.57) water sources in sheep; age >1 year old (OR = 3.45) and with drinking from pond (OR = 6.03) and pipe (OR = 11.61) water sources in goats; with the use of pond (OR = 5.60) and pipe (OR = 10.68) water sources in cattle; and in >4-year-old camels (OR = 2.49). In conclusion,T. gondii infection is common and widespread among the domestic ruminants of the study area, indicating the potential transmission to humans from these animals when they are used as a source of food. Hence, it is crucial to raise awareness of the people aboutT. gondii infection and conduct further study to explore the impact of the disease on food animal production.


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## Body

## 1. Introduction

Toxoplasma gondii is an obligate intracellular protozoan parasite with worldwide distribution which can infect all warm blooded animals and man. Most animals and man serve as intermediate hosts, while domestic cats and wild felids are definitive hosts that have an important role in the transmission ofT. gondii infection by shedding oocysts to the environment. Animals and humans can acquireT. gondii infection by ingesting feed and water contaminated with cats’ faeces containing infective oocysts and animal tissues with viable cysts ofT. gondii and congenitally [1].Toxoplasmosis is an economically important disease of livestock, causing abortion, stillbirth, fetal malformation, preterm deliveries, and neonatal death predominantly in sheep and goats infected byT. gondii, subsequently creating a potential challenge to the small ruminant industry worldwide [2]. Food animals infected withT. gondii pose a risk for the public, since consumption of raw or undercooked meat from such animals can facilitate zoonotic transmission. Moreover,T. gondii can be congenitally transmitted to the foetus during pregnancy [1, 3, 4].Several reports have indicated a great variation on the seroprevalence ofT. gondii infection in domestic ruminants across the world and it ranges from 3% to 92% in sheep [3, 5], from 5% to 77% in goats [3, 6, 7], and from 0% to 99% in cattle [8]. In Africa, the reported seroprevalence in animals varied between 3.6% and 57.5% [9–13].The estimated domestic ruminant population of Ethiopia in millions is sheep (27.35), goats (28.16), cattle (55.03), and camels (1.10) [14]. These large populations of domestic ruminants are mostly raised for milk, meat production, and breeding purpose. The seroprevalence ofT. gondii infection in Ethiopia ranges from 22.9% to 54.7% in sheep and from 11.6% to 74.8% in goats [15–20]. Aside from that, the only report found on the seroprevalenceT. gondii infection in cattle was that of 6.6% in Central Ethiopia [16]. Nonetheless, to date, there is no report from East Hararghe zone. Therefore, this study was carried out to bridge this information gap with the objectives of determining the seroprevalence and identifying the potential risk factors ofT. gondii infection in domestic ruminants of East Hararghe zone.


## 2. Materials and Methods

### 2.1. Study Area

The study was conducted in three selected districts of East Hararghe zone of Oromia region, Ethiopia. The districts were found at an altitude ranging from 950 to 2950 meters above sea level (masl). Accordingly, Gursum district is located at 9°7′–32°14′N latitude and 42°17′–42°38′E longitude with an altitude range of 1200–2950 masl; Babille district is located at 8°9′–9°23′N latitude and 41°16′–41°46′E longitude with an altitude ranging from 950 to 2000 masl; and Haramaya district is located at 9°9′–9°32′N latitude and 41°50′–42°05′E longitude with an altitude ranging from 1600 to 2140 masl. The districts are inhabited mainly by the “Oromo” tribe. Crop production and livestock rearing are the main economic activities in the rural areas, while small-scale trade is practiced in urban areas. Sorghum, maize, groundnut,“chat” (“khat”), and wheat are the main crops produced [21].


### 2.2. Study Animals and Design

The study animals comprised indigenous sheep, goats, cattle, and camels kept under extensive grazing system. Districts were selected purposively depending on their accessibility. Within the districts, 38“kebeles” (lowest administrative units) from both rural and urban areas were identified by simple random sampling from the lists obtained from the respective district administrations.The sample size was determined using a method recommended by Thrusfield [22]. A total of 1360 animals (sheep = 332, goats = 410, cattle = 326, and camels = 292) were sampled based on expected prevalence of 57.4% for sheep and 26% for goats [18] and 50% for both cattle and camels at 5% absolute precision and 95% confidence level. The sample size was allocated proportionally to the selected study districts. Individual sample units were identified systematically at night resting places, grazing areas, and watering points. Only sheep, goats, and cattle above six months of age and camels above two years of age were included in the study.


### 2.3. Blood Samples Collection and Serology

A total of 1360 animal sera were collected and analyzed from July 2011 to September 2013. Approximately 5–10 ml of blood was drawn from the jugular vein using plain vacutainer tubes and kept overnight at room temperature to clot for serum separation. Aliquots of sera were obtained by centrifugation at 3000 revolutions per minute for 10 min and the sera were transported to the parasitology laboratory of College of Veterinary Medicine and Agriculture at Bishoftu (Debre Zeyit) in ice box and stored at −20°C until they were tested.All sera were tested for anti-T. gondii IgG antibodies using indirect ELISA multispecies diagnostic kit (ID VET Innovative Diagnostic, ID Screen, Montpellier, France). On each working day, only the required amount of antigen and sera were thawed prior to serological testing. The preparation of the reagents and the iELISA test were performed based on the manufacturer’s recommendation at the National Animal Health Diagnostic and Investigation Center (NAHDIC) Sebeta, Ethiopia. Positive and negative controls were included in each test and an animal was considered to be infected when the serum presented an OD% ≥ 50% with ELISA. Herds or flocks were considered asT. gondii seropositive, when at least one animal was tested positive.


### 2.4. Questionnaire Survey

100 verbally consented owners of domestic ruminants whose herds and flocks were involved in the survey were interviewed using a structured close-ended questionnaire. The gathered information included the demographic characteristics of the animals such as age, sex, breed, herd size, and physiological status of the animals and their husbandry including house types, feed storage facilities, grazing types, and water sources as well as cats holding and the presence of feral cats in the vicinity (variables obtained from literatures).


### 2.5. Statistical Analysis

The data were analyzed using STATA version 11.0 for MA Windows (Stata Corp., College Station, USA). The data were categorized to make the analysis easy. Accordingly, sheep and goats were classified in two groups as ≤1 year and >1 year old, cattle into three groups as ≤1 year, >1–5 years, and >5 years old, and camels into two groups, ≤4 years and >4 years old. The flock/herd size for sheep, goats, and cattle was considered as small (<10 animals) or large (≥10 animals), while for camels it was considered as small (≤34 animals) or large (>34 animals). Type of housing with total confinement is categorized as pen for sheep and goats and barn for cattle, while it is classed as fence for those with access to the outside. Water source was classified as mixed (river, stream, pond, and well), pond, and pipe water (except camels). Species seroprevalence and the association of risk factors as independent categorical variable withT. gondii seropositivity were analyzed by the chi-square test (χ2). Logistic regression analysis was performed to measure the strength of association between the potential risk factors andT. gondii seropositivity. Noncollinear variables with values of P<0.20 in univariable analysis at 95% confidence level were entered into multivariable logistic regression model. The level of statistical significance was set as P<0.05.


## 2.1. Study Area

The study was conducted in three selected districts of East Hararghe zone of Oromia region, Ethiopia. The districts were found at an altitude ranging from 950 to 2950 meters above sea level (masl). Accordingly, Gursum district is located at 9°7′–32°14′N latitude and 42°17′–42°38′E longitude with an altitude range of 1200–2950 masl; Babille district is located at 8°9′–9°23′N latitude and 41°16′–41°46′E longitude with an altitude ranging from 950 to 2000 masl; and Haramaya district is located at 9°9′–9°32′N latitude and 41°50′–42°05′E longitude with an altitude ranging from 1600 to 2140 masl. The districts are inhabited mainly by the “Oromo” tribe. Crop production and livestock rearing are the main economic activities in the rural areas, while small-scale trade is practiced in urban areas. Sorghum, maize, groundnut,“chat” (“khat”), and wheat are the main crops produced [21].


## 2.2. Study Animals and Design

The study animals comprised indigenous sheep, goats, cattle, and camels kept under extensive grazing system. Districts were selected purposively depending on their accessibility. Within the districts, 38“kebeles” (lowest administrative units) from both rural and urban areas were identified by simple random sampling from the lists obtained from the respective district administrations.The sample size was determined using a method recommended by Thrusfield [22]. A total of 1360 animals (sheep = 332, goats = 410, cattle = 326, and camels = 292) were sampled based on expected prevalence of 57.4% for sheep and 26% for goats [18] and 50% for both cattle and camels at 5% absolute precision and 95% confidence level. The sample size was allocated proportionally to the selected study districts. Individual sample units were identified systematically at night resting places, grazing areas, and watering points. Only sheep, goats, and cattle above six months of age and camels above two years of age were included in the study.


## 2.3. Blood Samples Collection and Serology

A total of 1360 animal sera were collected and analyzed from July 2011 to September 2013. Approximately 5–10 ml of blood was drawn from the jugular vein using plain vacutainer tubes and kept overnight at room temperature to clot for serum separation. Aliquots of sera were obtained by centrifugation at 3000 revolutions per minute for 10 min and the sera were transported to the parasitology laboratory of College of Veterinary Medicine and Agriculture at Bishoftu (Debre Zeyit) in ice box and stored at −20°C until they were tested.All sera were tested for anti-T. gondii IgG antibodies using indirect ELISA multispecies diagnostic kit (ID VET Innovative Diagnostic, ID Screen, Montpellier, France). On each working day, only the required amount of antigen and sera were thawed prior to serological testing. The preparation of the reagents and the iELISA test were performed based on the manufacturer’s recommendation at the National Animal Health Diagnostic and Investigation Center (NAHDIC) Sebeta, Ethiopia. Positive and negative controls were included in each test and an animal was considered to be infected when the serum presented an OD% ≥ 50% with ELISA. Herds or flocks were considered asT. gondii seropositive, when at least one animal was tested positive.


## 2.4. Questionnaire Survey

100 verbally consented owners of domestic ruminants whose herds and flocks were involved in the survey were interviewed using a structured close-ended questionnaire. The gathered information included the demographic characteristics of the animals such as age, sex, breed, herd size, and physiological status of the animals and their husbandry including house types, feed storage facilities, grazing types, and water sources as well as cats holding and the presence of feral cats in the vicinity (variables obtained from literatures).


## 2.5. Statistical Analysis

The data were analyzed using STATA version 11.0 for MA Windows (Stata Corp., College Station, USA). The data were categorized to make the analysis easy. Accordingly, sheep and goats were classified in two groups as ≤1 year and >1 year old, cattle into three groups as ≤1 year, >1–5 years, and >5 years old, and camels into two groups, ≤4 years and >4 years old. The flock/herd size for sheep, goats, and cattle was considered as small (<10 animals) or large (≥10 animals), while for camels it was considered as small (≤34 animals) or large (>34 animals). Type of housing with total confinement is categorized as pen for sheep and goats and barn for cattle, while it is classed as fence for those with access to the outside. Water source was classified as mixed (river, stream, pond, and well), pond, and pipe water (except camels). Species seroprevalence and the association of risk factors as independent categorical variable withT. gondii seropositivity were analyzed by the chi-square test (χ2). Logistic regression analysis was performed to measure the strength of association between the potential risk factors andT. gondii seropositivity. Noncollinear variables with values of P<0.20 in univariable analysis at 95% confidence level were entered into multivariable logistic regression model. The level of statistical significance was set as P<0.05.


## 3. Results

### 3.1. Serological Findings

Out of 1360 sera of domestic ruminants tested, the presence of anti-T. gondii IgG antibodies was detected in 302 (22.2%, 95% CI: 20.0%–24.5%) of them that belonged to 173 (49.29%, 95% CI: 43.94%–54.65%) herds or flocks. The highest seroprevalence of infection was observed in sheep (33.7%) and the lowest was in cattle (10.7%). The distribution ofT. gondii infection among domestic ruminants is presented in Table 1.T. gondii infection was detected in 32 out of the 38 (84.2%) farm areas/“kebeles” included in the study.Table 1
Seroprevalence ofT. gondii infection in domestic ruminants.
Species Animal level Herd/flock level N No. of positive Percentage (%) 95% CI N ∗ No. of positive Percentage (%) 95% CI Sheep 332 112 33.73 28.66–39.10 102 62 60.78 50.62–70.31 Goats 410 113 27.56 23.29–32.16 120 67 55.83 46.48–64.89 Cattle 326 35 10.74 7.59–14.61 82 19 23.17 14.56–33.80 Camels 292 42 14.38 10.57–18.94 47 25 53.19 38.08–67.89  Total 1360 302 22.2 20.02–24.51 351 173 49.29 43.94–54.65 N: number of animals tested; No.: number; N∗: number of herds/flocks tested; CI: confidence interval (CI).In a univariable analysis, goats had high risk ofT. gondii infection (OR = 0.75, 95% CI: 0.55–1.02, P=0.069) comparable with that of sheep, whereas cattle (OR = 0.24, 95% CI: 0.16–0.36, P<0.001) and camel (OR = 0.33, 95% CI: 0.22–0.49, P<0.001) were at low risk.


#### 3.1.1. Sheep

A multivariable logistic regression analysis showed that sex of the animal and water source were risk factors for increased seroprevalence. A higher risk ofT. gondii infection occurred in females (OR = 2.63, 95% CI: 1.18–5.88, P=0.019) than in males in those given pipe water (OR = 9.57, 95% CI: 5.00–18.33, P<0.001) and pond water (OR = 4.25, 95% CI: 2.15–8.38, P<0.001) compared with those that drank from a mixed water source (Table 2). But the variables district, age, and cats contact were insignificant (P>0.05). Nonetheless, relatively higher seroprevalence was observed in sheep from Babille district (45.7%) than from Gursum (30.8%) and Haramaya (26.3%), in >1 year old (35.2%) than in ≤1 year old (23.1%), and in those having contact with cats (40.0%) than in those not in contact (30.0%).Table 2
Analysis of risk factors related toT. gondii seropositivity in sheep at animal level (n=332).
Variables Category Number tested Positive (%) Crude OR (95% CI) Adjusted OR (95% CI) P value District Haramaya 95 25 (26.3) 1.00 (ref.) 1.00 (ref.) Gursum 143 44 (30.8) 1.24 (0.70–2.22) 0.69 (0.35–1.34) 0.270 Babille 94 43 (45.7) 2.36 (1.28–4.35) 0.95 (0.46–1.94) 0.881  Environment Rural 253 58 (22.9) 1.00 (ref.) — — Urban 79 54 (68.4) 7.26 (4.16–12.68) — —  Sex Male 68 11 (16.2) 1.00 (ref.) 1.00 (ref.) — Female 264 101 (38.3) 3.21 (1.61–6.41) 2.63 (1.18–5.88) 0.019∗  Age ≤1 year 39 9 (23.1) 1.00 (ref.) 1.00 (ref.) >1 year 293 103 (35.2) 1.81 (0.83–3.95) 1.15 (0.45–2.91) 0.772  Flock size Small 270 89 (33.0) 1.00 (ref.) — — Large 62 23 (37.1) 1.20 (0.68–2.13) — —  Cats contact No 207 62 (30.0) 1.00 (ref.) 1.00 (ref.) — Yes 125 50 (40.0) 1.56 (0.98–2.48) 1.28 (0.74–2.20) 0.371  Water source Mixed† 198 34 (17.2) 1.00 (ref.) 1.00 (ref.) Pond‡ 55 24 (43.6) 3.73 (1.95–7.14) 4.25 (2.15–8.38) <0.001∗ Pipe water 79 54 (68.4) 10.42 (5.71–19.00) 9.57 (5.00–18.33) <0.001∗  House type Pen 24 3 (12.5) 1.00 (ref.) — — Both 207 48 (23.2) 2.11 (0.60–7.39) — — Fence 101 61 (60.4) 10.68 (2.99–38.15) — — Mixed†: river, stream water, and well; Pond‡: stagnant water; OR: odds ratio; CI: confidence interval. ∗Significant.


#### 3.1.2. Goats

District, age, and water sources were identified as risk factors forT. gondii infection. An increased risk of infection occurred in goats >1 year old (OR = 3.45, 95% CI: 1.34–8.90, P=0.010) compared to ≤1 year and in those given pipe (OR = 11.61, 95% CI: 4.35–30.95, P<0.001) and pond water (OR = 6.03, 95% CI: 2.42–15.05, P<0.001) than in those that drank from mixed water sources. In contrast, Babille district (OR = 0.15, 95% CI = 0.05–0.48, P<0.001) was found to be a lower risk for goats (Table 3). Variables such as sex, breed, and flock size were not found to be significant (P>0.05). However, raised seroprevalence was obtained in females (30.6%) compared to males (17.2%) and in small flock size (29.3%) compared to large (20.9%).Table 3
Logistic regression analysis of risk factors withT. gondii seropositivity in goats at animal level (n=410).
Variables Category Number tested Positive (%) Crude OR (95% CI) Adjusted OR (95% CI) P value District Haramaya 121 22 (18.2) 1.00 (ref.) 1.00 (ref.) — Gursum 176 61 (34.7) 2.39 (1.37–4.16) 0.52 (0.20–1.36) 0.185 Babille 113 30 (26.6) 1.63 (0.87–3.03) 0.15 (0.05–0.48) <0.001∗  Environment Rural 340 79 (23.2) 1.00 (ref.) — — Urban 70 34 (48.6) 3.12 (1.83–5.31) — —  Sex Male 93 16 (17.2) 1.00 (ref.) 1.00 (ref.) – Female 317 97 (30.6) 2.12 (1.18–3.82) 1.65 (0.86–3.18) 0.134  Age ≤1 year 63 6 (9.5) 1.00 (ref.) 1.00 (ref.) — >1 year 347 107 (30.8) 4.24 (1.77–10.12) 3.45 (1.34–8.90) 0.010∗  Breed Hararghe highland 29 5 (17.2) 1.00 (ref.) 1.00 (ref.) — Long ear Somali 349 95 (27.2) 1.80 (0.67–4.84) 1.10 (0.36–3.39) 0.863 Undetermined 32 13 (40.6) 3.28 (0.99–10.84) 2.77 (0.68–11.31) 0.155  Flock size Small 324 95 (29.3) 1.00 (ref.) 1.00 (ref.) — Large 86 18 (20.9) 0.64 (0.36–1.13) 0.85 (0.45–1.60) 0.607  Cats contact No 270 70 (25.9) 1.00 (ref.) — — Yes 140 43 (30.7) 1.27 (0.81–1.99) — —  Water source Mixed† 188 29 (15.4) 1.00 (ref.) 1.00 (ref.) — Pond‡ 152 50 (32.9) 2.69 (1.60–4.52) 6.03 (2.42–15.05) <0.001∗ Pipe water 70 34 (48.6) 5.18 (2.80–9.56) 11.61 (4.35–30.95) <0.001∗  House type Pen 27 5 (18.5) 1.00 (ref.) — — Both 292 73 (25.0) 1.47 (0.54–4.01) — — Fence 91 35 (38.5) 2.75 (0.95–7.93) — — Mixed†: river, stream water, and well; Pond‡: stagnant water; OR: odds ratio; CI: confidence interval. ∗Significant.


#### 3.1.3. Cattle

Multivariable logistic regression analysis indicated that district, herd size, and water source were risk factors forT. gondii infection. Using pond water (OR = 5.60, 95% CI: 2.12–14.78, P<0.001) and pipe water sources (OR = 10.68, 95% CI: 2.23–51.22, P=0.003) had significantly increased the risk of acquiringT. gondii infection compared to using mixed water sources, while living in Gursum district (OR = 0.19, 95% CI: 0.06–0.59, P=0.004) and belonging to large herd size (OR = 0.35, 95% CI: 0.13–0.97, P=0.044) were associated with lower risk (Table 4). Among the variables included in the statistical analysis, cats contact and house types were not significant (P>0.05).Table 4
Logistic regression analysis of risk factors withT. gondii seropositivity in cattle at animal level (n=326).
Variables Category Number tested Positive (%) Crude OR (95% CI) Adjusted OR (95% CI) P value District Haramaya 87 14 (16.1) 1.00 (ref.) 1.00 (ref.) — Gursum 153 9 (5.9) 0.33 (0.13–0.79) 0.19 (0.06–0.59) 0.004∗ Babille 86 12 (14.0) 0.85 (0.37–1.95) 1.60 (0.49–5.16) 0.434  Environment Rural 303 30 (9.9) 1.00 (ref.) — Urban 23 5 (21.7) 2.53 (0.88–7.30) —  Sex Male 97 11 (11.3) 1.00 (ref.) — Female 229 24 (10.5) 0.92 (0.43–1.95) —  Age ≤1 year 34 3 (8.8) 1.00 (ref.) — >1–5 years 186 19 (10.2) 1.18 (0.33–4.21) — >5 years 106 13 (12.3) 1.44 (0.39–5.40) —  Herd size Small 218 27 (12.4) 1.00 (ref.) 1.00 (ref.) — Large 108 8 (7.4) 0.57 (0.25–1.29) 0.35 (0.13–0.97) 0.044∗  Cats contact No 223 19 (8.5) 1.00 (ref.) 1.00 (ref.) — Yes 103 16 (15.5) 1.97 (0.97–4.02) 2.23 (0.86–5.77) 0.097  Water source Mixed† 234 14 (6.0) 1.00 (ref.) 1.00 (ref.) — Pond‡ 69 16 (23.2) 4.75 (2.18–10.32) 5.60 (2.12–14.78) <0.001∗ Pipe water 23 5 (21.7) 4.37 (1.41–13.49) 10.68 (2.23–51.22) 0.003∗  House type Barn 29 5 (17.2) 1.00 (ref.) 1.00 (ref.) — Both 246 23 (9.4) 0.50 (0.17–1.42) 0.23 (0.05–0.99) 0.049 Fence 51 7 (13.7) 0.76 (0.22–2.67) 0.42 (0.08–2.32) 0.318 Mixed†: river, stream water, and well; Pond‡: stagnant water; OR: odds ratio; CI: confidence interval. ∗Significant.


#### 3.1.4. Camels

The sole risk factor identified in camels is age. Camels in the age group of >4 years (OR = 2.49, 95% CI: 1.14–5.45,P=0.022) showed an increased risk ofT. gondii infection than those ≤ 4 years (Table 5). Although not statistically significant, difference seen (P>0.05) inT. gondii infection in camels having contact with cats (21.7%) was higher than that seen in those not having contact (13.0%).Table 5
Analysis of risk factors withT. gondii seropositivity in camels at animal level (n=292).
Variables Category Number tested Positive (%) Crude OR (95% CI) Adjusted OR (95% CI) P value District Gursum 95 13 (13.7) 1.00 (ref.) — — Babille 197 29 (14.7) 1.09 (0.54–2.20) — — Sex Male 73 11 (15.1) 1.00 (ref.) — — Female 219 31 (14.2) 0.93 (0.44–1.96) — — Age ≤4 years 110 9 (8.2) 1.00 (ref.) 1.00 (ref.) — >4 years 182 33 (18.1) 2.49 (1.14–5.42) 2.49 (1.14–5.45) 0.022∗ Herd size Small 203 30 (14.8) 1.00 (ref.) — — Large 89 12 (13.5) 0.90 (0.44–1.85) — — Cat contact No 246 32 (13.0) 1.00 (ref.) 1.00 (ref.) — Yes 46 10 (21.7) 1.86 (0.84–4.10) 1.87 (0.84–4.18) 0.127 Water source Mixed† 215 30 (14.0) 1.00 (ref.) — — Pond‡ 77 12 (15.6) 1.14 (0.55–2.35) — — Mixed†: river, stream water, and well; Pond‡: stagnant water; OR: odds ratio; CI: confidence interval. ∗Significant.


## 3.1. Serological Findings

Out of 1360 sera of domestic ruminants tested, the presence of anti-T. gondii IgG antibodies was detected in 302 (22.2%, 95% CI: 20.0%–24.5%) of them that belonged to 173 (49.29%, 95% CI: 43.94%–54.65%) herds or flocks. The highest seroprevalence of infection was observed in sheep (33.7%) and the lowest was in cattle (10.7%). The distribution ofT. gondii infection among domestic ruminants is presented in Table 1.T. gondii infection was detected in 32 out of the 38 (84.2%) farm areas/“kebeles” included in the study.Table 1
Seroprevalence ofT. gondii infection in domestic ruminants.
Species Animal level Herd/flock level N No. of positive Percentage (%) 95% CI N ∗ No. of positive Percentage (%) 95% CI Sheep 332 112 33.73 28.66–39.10 102 62 60.78 50.62–70.31 Goats 410 113 27.56 23.29–32.16 120 67 55.83 46.48–64.89 Cattle 326 35 10.74 7.59–14.61 82 19 23.17 14.56–33.80 Camels 292 42 14.38 10.57–18.94 47 25 53.19 38.08–67.89  Total 1360 302 22.2 20.02–24.51 351 173 49.29 43.94–54.65 N: number of animals tested; No.: number; N∗: number of herds/flocks tested; CI: confidence interval (CI).In a univariable analysis, goats had high risk ofT. gondii infection (OR = 0.75, 95% CI: 0.55–1.02, P=0.069) comparable with that of sheep, whereas cattle (OR = 0.24, 95% CI: 0.16–0.36, P<0.001) and camel (OR = 0.33, 95% CI: 0.22–0.49, P<0.001) were at low risk.


### 3.1.1. Sheep

A multivariable logistic regression analysis showed that sex of the animal and water source were risk factors for increased seroprevalence. A higher risk ofT. gondii infection occurred in females (OR = 2.63, 95% CI: 1.18–5.88, P=0.019) than in males in those given pipe water (OR = 9.57, 95% CI: 5.00–18.33, P<0.001) and pond water (OR = 4.25, 95% CI: 2.15–8.38, P<0.001) compared with those that drank from a mixed water source (Table 2). But the variables district, age, and cats contact were insignificant (P>0.05). Nonetheless, relatively higher seroprevalence was observed in sheep from Babille district (45.7%) than from Gursum (30.8%) and Haramaya (26.3%), in >1 year old (35.2%) than in ≤1 year old (23.1%), and in those having contact with cats (40.0%) than in those not in contact (30.0%).Table 2
Analysis of risk factors related toT. gondii seropositivity in sheep at animal level (n=332).
Variables Category Number tested Positive (%) Crude OR (95% CI) Adjusted OR (95% CI) P value District Haramaya 95 25 (26.3) 1.00 (ref.) 1.00 (ref.) Gursum 143 44 (30.8) 1.24 (0.70–2.22) 0.69 (0.35–1.34) 0.270 Babille 94 43 (45.7) 2.36 (1.28–4.35) 0.95 (0.46–1.94) 0.881  Environment Rural 253 58 (22.9) 1.00 (ref.) — — Urban 79 54 (68.4) 7.26 (4.16–12.68) — —  Sex Male 68 11 (16.2) 1.00 (ref.) 1.00 (ref.) — Female 264 101 (38.3) 3.21 (1.61–6.41) 2.63 (1.18–5.88) 0.019∗  Age ≤1 year 39 9 (23.1) 1.00 (ref.) 1.00 (ref.) >1 year 293 103 (35.2) 1.81 (0.83–3.95) 1.15 (0.45–2.91) 0.772  Flock size Small 270 89 (33.0) 1.00 (ref.) — — Large 62 23 (37.1) 1.20 (0.68–2.13) — —  Cats contact No 207 62 (30.0) 1.00 (ref.) 1.00 (ref.) — Yes 125 50 (40.0) 1.56 (0.98–2.48) 1.28 (0.74–2.20) 0.371  Water source Mixed† 198 34 (17.2) 1.00 (ref.) 1.00 (ref.) Pond‡ 55 24 (43.6) 3.73 (1.95–7.14) 4.25 (2.15–8.38) <0.001∗ Pipe water 79 54 (68.4) 10.42 (5.71–19.00) 9.57 (5.00–18.33) <0.001∗  House type Pen 24 3 (12.5) 1.00 (ref.) — — Both 207 48 (23.2) 2.11 (0.60–7.39) — — Fence 101 61 (60.4) 10.68 (2.99–38.15) — — Mixed†: river, stream water, and well; Pond‡: stagnant water; OR: odds ratio; CI: confidence interval. ∗Significant.


### 3.1.2. Goats

District, age, and water sources were identified as risk factors forT. gondii infection. An increased risk of infection occurred in goats >1 year old (OR = 3.45, 95% CI: 1.34–8.90, P=0.010) compared to ≤1 year and in those given pipe (OR = 11.61, 95% CI: 4.35–30.95, P<0.001) and pond water (OR = 6.03, 95% CI: 2.42–15.05, P<0.001) than in those that drank from mixed water sources. In contrast, Babille district (OR = 0.15, 95% CI = 0.05–0.48, P<0.001) was found to be a lower risk for goats (Table 3). Variables such as sex, breed, and flock size were not found to be significant (P>0.05). However, raised seroprevalence was obtained in females (30.6%) compared to males (17.2%) and in small flock size (29.3%) compared to large (20.9%).Table 3
Logistic regression analysis of risk factors withT. gondii seropositivity in goats at animal level (n=410).
Variables Category Number tested Positive (%) Crude OR (95% CI) Adjusted OR (95% CI) P value District Haramaya 121 22 (18.2) 1.00 (ref.) 1.00 (ref.) — Gursum 176 61 (34.7) 2.39 (1.37–4.16) 0.52 (0.20–1.36) 0.185 Babille 113 30 (26.6) 1.63 (0.87–3.03) 0.15 (0.05–0.48) <0.001∗  Environment Rural 340 79 (23.2) 1.00 (ref.) — — Urban 70 34 (48.6) 3.12 (1.83–5.31) — —  Sex Male 93 16 (17.2) 1.00 (ref.) 1.00 (ref.) – Female 317 97 (30.6) 2.12 (1.18–3.82) 1.65 (0.86–3.18) 0.134  Age ≤1 year 63 6 (9.5) 1.00 (ref.) 1.00 (ref.) — >1 year 347 107 (30.8) 4.24 (1.77–10.12) 3.45 (1.34–8.90) 0.010∗  Breed Hararghe highland 29 5 (17.2) 1.00 (ref.) 1.00 (ref.) — Long ear Somali 349 95 (27.2) 1.80 (0.67–4.84) 1.10 (0.36–3.39) 0.863 Undetermined 32 13 (40.6) 3.28 (0.99–10.84) 2.77 (0.68–11.31) 0.155  Flock size Small 324 95 (29.3) 1.00 (ref.) 1.00 (ref.) — Large 86 18 (20.9) 0.64 (0.36–1.13) 0.85 (0.45–1.60) 0.607  Cats contact No 270 70 (25.9) 1.00 (ref.) — — Yes 140 43 (30.7) 1.27 (0.81–1.99) — —  Water source Mixed† 188 29 (15.4) 1.00 (ref.) 1.00 (ref.) — Pond‡ 152 50 (32.9) 2.69 (1.60–4.52) 6.03 (2.42–15.05) <0.001∗ Pipe water 70 34 (48.6) 5.18 (2.80–9.56) 11.61 (4.35–30.95) <0.001∗  House type Pen 27 5 (18.5) 1.00 (ref.) — — Both 292 73 (25.0) 1.47 (0.54–4.01) — — Fence 91 35 (38.5) 2.75 (0.95–7.93) — — Mixed†: river, stream water, and well; Pond‡: stagnant water; OR: odds ratio; CI: confidence interval. ∗Significant.


### 3.1.3. Cattle

Multivariable logistic regression analysis indicated that district, herd size, and water source were risk factors forT. gondii infection. Using pond water (OR = 5.60, 95% CI: 2.12–14.78, P<0.001) and pipe water sources (OR = 10.68, 95% CI: 2.23–51.22, P=0.003) had significantly increased the risk of acquiringT. gondii infection compared to using mixed water sources, while living in Gursum district (OR = 0.19, 95% CI: 0.06–0.59, P=0.004) and belonging to large herd size (OR = 0.35, 95% CI: 0.13–0.97, P=0.044) were associated with lower risk (Table 4). Among the variables included in the statistical analysis, cats contact and house types were not significant (P>0.05).Table 4
Logistic regression analysis of risk factors withT. gondii seropositivity in cattle at animal level (n=326).
Variables Category Number tested Positive (%) Crude OR (95% CI) Adjusted OR (95% CI) P value District Haramaya 87 14 (16.1) 1.00 (ref.) 1.00 (ref.) — Gursum 153 9 (5.9) 0.33 (0.13–0.79) 0.19 (0.06–0.59) 0.004∗ Babille 86 12 (14.0) 0.85 (0.37–1.95) 1.60 (0.49–5.16) 0.434  Environment Rural 303 30 (9.9) 1.00 (ref.) — Urban 23 5 (21.7) 2.53 (0.88–7.30) —  Sex Male 97 11 (11.3) 1.00 (ref.) — Female 229 24 (10.5) 0.92 (0.43–1.95) —  Age ≤1 year 34 3 (8.8) 1.00 (ref.) — >1–5 years 186 19 (10.2) 1.18 (0.33–4.21) — >5 years 106 13 (12.3) 1.44 (0.39–5.40) —  Herd size Small 218 27 (12.4) 1.00 (ref.) 1.00 (ref.) — Large 108 8 (7.4) 0.57 (0.25–1.29) 0.35 (0.13–0.97) 0.044∗  Cats contact No 223 19 (8.5) 1.00 (ref.) 1.00 (ref.) — Yes 103 16 (15.5) 1.97 (0.97–4.02) 2.23 (0.86–5.77) 0.097  Water source Mixed† 234 14 (6.0) 1.00 (ref.) 1.00 (ref.) — Pond‡ 69 16 (23.2) 4.75 (2.18–10.32) 5.60 (2.12–14.78) <0.001∗ Pipe water 23 5 (21.7) 4.37 (1.41–13.49) 10.68 (2.23–51.22) 0.003∗  House type Barn 29 5 (17.2) 1.00 (ref.) 1.00 (ref.) — Both 246 23 (9.4) 0.50 (0.17–1.42) 0.23 (0.05–0.99) 0.049 Fence 51 7 (13.7) 0.76 (0.22–2.67) 0.42 (0.08–2.32) 0.318 Mixed†: river, stream water, and well; Pond‡: stagnant water; OR: odds ratio; CI: confidence interval. ∗Significant.


### 3.1.4. Camels

The sole risk factor identified in camels is age. Camels in the age group of >4 years (OR = 2.49, 95% CI: 1.14–5.45,P=0.022) showed an increased risk ofT. gondii infection than those ≤ 4 years (Table 5). Although not statistically significant, difference seen (P>0.05) inT. gondii infection in camels having contact with cats (21.7%) was higher than that seen in those not having contact (13.0%).Table 5
Analysis of risk factors withT. gondii seropositivity in camels at animal level (n=292).
Variables Category Number tested Positive (%) Crude OR (95% CI) Adjusted OR (95% CI) P value District Gursum 95 13 (13.7) 1.00 (ref.) — — Babille 197 29 (14.7) 1.09 (0.54–2.20) — — Sex Male 73 11 (15.1) 1.00 (ref.) — — Female 219 31 (14.2) 0.93 (0.44–1.96) — — Age ≤4 years 110 9 (8.2) 1.00 (ref.) 1.00 (ref.) — >4 years 182 33 (18.1) 2.49 (1.14–5.42) 2.49 (1.14–5.45) 0.022∗ Herd size Small 203 30 (14.8) 1.00 (ref.) — — Large 89 12 (13.5) 0.90 (0.44–1.85) — — Cat contact No 246 32 (13.0) 1.00 (ref.) 1.00 (ref.) — Yes 46 10 (21.7) 1.86 (0.84–4.10) 1.87 (0.84–4.18) 0.127 Water source Mixed† 215 30 (14.0) 1.00 (ref.) — — Pond‡ 77 12 (15.6) 1.14 (0.55–2.35) — — Mixed†: river, stream water, and well; Pond‡: stagnant water; OR: odds ratio; CI: confidence interval. ∗Significant.


## 3.1.1. Sheep

A multivariable logistic regression analysis showed that sex of the animal and water source were risk factors for increased seroprevalence. A higher risk ofT. gondii infection occurred in females (OR = 2.63, 95% CI: 1.18–5.88, P=0.019) than in males in those given pipe water (OR = 9.57, 95% CI: 5.00–18.33, P<0.001) and pond water (OR = 4.25, 95% CI: 2.15–8.38, P<0.001) compared with those that drank from a mixed water source (Table 2). But the variables district, age, and cats contact were insignificant (P>0.05). Nonetheless, relatively higher seroprevalence was observed in sheep from Babille district (45.7%) than from Gursum (30.8%) and Haramaya (26.3%), in >1 year old (35.2%) than in ≤1 year old (23.1%), and in those having contact with cats (40.0%) than in those not in contact (30.0%).Table 2
Analysis of risk factors related toT. gondii seropositivity in sheep at animal level (n=332).
Variables Category Number tested Positive (%) Crude OR (95% CI) Adjusted OR (95% CI) P value District Haramaya 95 25 (26.3) 1.00 (ref.) 1.00 (ref.) Gursum 143 44 (30.8) 1.24 (0.70–2.22) 0.69 (0.35–1.34) 0.270 Babille 94 43 (45.7) 2.36 (1.28–4.35) 0.95 (0.46–1.94) 0.881  Environment Rural 253 58 (22.9) 1.00 (ref.) — — Urban 79 54 (68.4) 7.26 (4.16–12.68) — —  Sex Male 68 11 (16.2) 1.00 (ref.) 1.00 (ref.) — Female 264 101 (38.3) 3.21 (1.61–6.41) 2.63 (1.18–5.88) 0.019∗  Age ≤1 year 39 9 (23.1) 1.00 (ref.) 1.00 (ref.) >1 year 293 103 (35.2) 1.81 (0.83–3.95) 1.15 (0.45–2.91) 0.772  Flock size Small 270 89 (33.0) 1.00 (ref.) — — Large 62 23 (37.1) 1.20 (0.68–2.13) — —  Cats contact No 207 62 (30.0) 1.00 (ref.) 1.00 (ref.) — Yes 125 50 (40.0) 1.56 (0.98–2.48) 1.28 (0.74–2.20) 0.371  Water source Mixed† 198 34 (17.2) 1.00 (ref.) 1.00 (ref.) Pond‡ 55 24 (43.6) 3.73 (1.95–7.14) 4.25 (2.15–8.38) <0.001∗ Pipe water 79 54 (68.4) 10.42 (5.71–19.00) 9.57 (5.00–18.33) <0.001∗  House type Pen 24 3 (12.5) 1.00 (ref.) — — Both 207 48 (23.2) 2.11 (0.60–7.39) — — Fence 101 61 (60.4) 10.68 (2.99–38.15) — — Mixed†: river, stream water, and well; Pond‡: stagnant water; OR: odds ratio; CI: confidence interval. ∗Significant.


## 3.1.2. Goats

District, age, and water sources were identified as risk factors forT. gondii infection. An increased risk of infection occurred in goats >1 year old (OR = 3.45, 95% CI: 1.34–8.90, P=0.010) compared to ≤1 year and in those given pipe (OR = 11.61, 95% CI: 4.35–30.95, P<0.001) and pond water (OR = 6.03, 95% CI: 2.42–15.05, P<0.001) than in those that drank from mixed water sources. In contrast, Babille district (OR = 0.15, 95% CI = 0.05–0.48, P<0.001) was found to be a lower risk for goats (Table 3). Variables such as sex, breed, and flock size were not found to be significant (P>0.05). However, raised seroprevalence was obtained in females (30.6%) compared to males (17.2%) and in small flock size (29.3%) compared to large (20.9%).Table 3
Logistic regression analysis of risk factors withT. gondii seropositivity in goats at animal level (n=410).
Variables Category Number tested Positive (%) Crude OR (95% CI) Adjusted OR (95% CI) P value District Haramaya 121 22 (18.2) 1.00 (ref.) 1.00 (ref.) — Gursum 176 61 (34.7) 2.39 (1.37–4.16) 0.52 (0.20–1.36) 0.185 Babille 113 30 (26.6) 1.63 (0.87–3.03) 0.15 (0.05–0.48) <0.001∗  Environment Rural 340 79 (23.2) 1.00 (ref.) — — Urban 70 34 (48.6) 3.12 (1.83–5.31) — —  Sex Male 93 16 (17.2) 1.00 (ref.) 1.00 (ref.) – Female 317 97 (30.6) 2.12 (1.18–3.82) 1.65 (0.86–3.18) 0.134  Age ≤1 year 63 6 (9.5) 1.00 (ref.) 1.00 (ref.) — >1 year 347 107 (30.8) 4.24 (1.77–10.12) 3.45 (1.34–8.90) 0.010∗  Breed Hararghe highland 29 5 (17.2) 1.00 (ref.) 1.00 (ref.) — Long ear Somali 349 95 (27.2) 1.80 (0.67–4.84) 1.10 (0.36–3.39) 0.863 Undetermined 32 13 (40.6) 3.28 (0.99–10.84) 2.77 (0.68–11.31) 0.155  Flock size Small 324 95 (29.3) 1.00 (ref.) 1.00 (ref.) — Large 86 18 (20.9) 0.64 (0.36–1.13) 0.85 (0.45–1.60) 0.607  Cats contact No 270 70 (25.9) 1.00 (ref.) — — Yes 140 43 (30.7) 1.27 (0.81–1.99) — —  Water source Mixed† 188 29 (15.4) 1.00 (ref.) 1.00 (ref.) — Pond‡ 152 50 (32.9) 2.69 (1.60–4.52) 6.03 (2.42–15.05) <0.001∗ Pipe water 70 34 (48.6) 5.18 (2.80–9.56) 11.61 (4.35–30.95) <0.001∗  House type Pen 27 5 (18.5) 1.00 (ref.) — — Both 292 73 (25.0) 1.47 (0.54–4.01) — — Fence 91 35 (38.5) 2.75 (0.95–7.93) — — Mixed†: river, stream water, and well; Pond‡: stagnant water; OR: odds ratio; CI: confidence interval. ∗Significant.


## 3.1.3. Cattle

Multivariable logistic regression analysis indicated that district, herd size, and water source were risk factors forT. gondii infection. Using pond water (OR = 5.60, 95% CI: 2.12–14.78, P<0.001) and pipe water sources (OR = 10.68, 95% CI: 2.23–51.22, P=0.003) had significantly increased the risk of acquiringT. gondii infection compared to using mixed water sources, while living in Gursum district (OR = 0.19, 95% CI: 0.06–0.59, P=0.004) and belonging to large herd size (OR = 0.35, 95% CI: 0.13–0.97, P=0.044) were associated with lower risk (Table 4). Among the variables included in the statistical analysis, cats contact and house types were not significant (P>0.05).Table 4
Logistic regression analysis of risk factors withT. gondii seropositivity in cattle at animal level (n=326).
Variables Category Number tested Positive (%) Crude OR (95% CI) Adjusted OR (95% CI) P value District Haramaya 87 14 (16.1) 1.00 (ref.) 1.00 (ref.) — Gursum 153 9 (5.9) 0.33 (0.13–0.79) 0.19 (0.06–0.59) 0.004∗ Babille 86 12 (14.0) 0.85 (0.37–1.95) 1.60 (0.49–5.16) 0.434  Environment Rural 303 30 (9.9) 1.00 (ref.) — Urban 23 5 (21.7) 2.53 (0.88–7.30) —  Sex Male 97 11 (11.3) 1.00 (ref.) — Female 229 24 (10.5) 0.92 (0.43–1.95) —  Age ≤1 year 34 3 (8.8) 1.00 (ref.) — >1–5 years 186 19 (10.2) 1.18 (0.33–4.21) — >5 years 106 13 (12.3) 1.44 (0.39–5.40) —  Herd size Small 218 27 (12.4) 1.00 (ref.) 1.00 (ref.) — Large 108 8 (7.4) 0.57 (0.25–1.29) 0.35 (0.13–0.97) 0.044∗  Cats contact No 223 19 (8.5) 1.00 (ref.) 1.00 (ref.) — Yes 103 16 (15.5) 1.97 (0.97–4.02) 2.23 (0.86–5.77) 0.097  Water source Mixed† 234 14 (6.0) 1.00 (ref.) 1.00 (ref.) — Pond‡ 69 16 (23.2) 4.75 (2.18–10.32) 5.60 (2.12–14.78) <0.001∗ Pipe water 23 5 (21.7) 4.37 (1.41–13.49) 10.68 (2.23–51.22) 0.003∗  House type Barn 29 5 (17.2) 1.00 (ref.) 1.00 (ref.) — Both 246 23 (9.4) 0.50 (0.17–1.42) 0.23 (0.05–0.99) 0.049 Fence 51 7 (13.7) 0.76 (0.22–2.67) 0.42 (0.08–2.32) 0.318 Mixed†: river, stream water, and well; Pond‡: stagnant water; OR: odds ratio; CI: confidence interval. ∗Significant.


## 3.1.4. Camels

The sole risk factor identified in camels is age. Camels in the age group of >4 years (OR = 2.49, 95% CI: 1.14–5.45,P=0.022) showed an increased risk ofT. gondii infection than those ≤ 4 years (Table 5). Although not statistically significant, difference seen (P>0.05) inT. gondii infection in camels having contact with cats (21.7%) was higher than that seen in those not having contact (13.0%).Table 5
Analysis of risk factors withT. gondii seropositivity in camels at animal level (n=292).
Variables Category Number tested Positive (%) Crude OR (95% CI) Adjusted OR (95% CI) P value District Gursum 95 13 (13.7) 1.00 (ref.) — — Babille 197 29 (14.7) 1.09 (0.54–2.20) — — Sex Male 73 11 (15.1) 1.00 (ref.) — — Female 219 31 (14.2) 0.93 (0.44–1.96) — — Age ≤4 years 110 9 (8.2) 1.00 (ref.) 1.00 (ref.) — >4 years 182 33 (18.1) 2.49 (1.14–5.42) 2.49 (1.14–5.45) 0.022∗ Herd size Small 203 30 (14.8) 1.00 (ref.) — — Large 89 12 (13.5) 0.90 (0.44–1.85) — — Cat contact No 246 32 (13.0) 1.00 (ref.) 1.00 (ref.) — Yes 46 10 (21.7) 1.86 (0.84–4.10) 1.87 (0.84–4.18) 0.127 Water source Mixed† 215 30 (14.0) 1.00 (ref.) — — Pond‡ 77 12 (15.6) 1.14 (0.55–2.35) — — Mixed†: river, stream water, and well; Pond‡: stagnant water; OR: odds ratio; CI: confidence interval. ∗Significant.


## 4. Discussion

The present study had given an insight on toxoplasmosis and revealed the widespread occurrence ofT. gondii infection among the domestic ruminants raised in East Hararghe zone. The observed seroprevalence ofT. gondii infection in sheep in this study is in agreement with those previously reported from Ethiopia, 31.59% from East and West Shewa Zones of Oromia Region [15] and 34% in Debre Birhan [17], and from elsewhere in the world, 29.41% and 32.9% from Brazil [5, 23] and 27.6% from Morocco [9]. But the current prevalence is slightly higher than the prevalence from central Ethiopia, 22.9% [16], Nigeria, 6.7% [10], Pakistan, 11.1% [24], and northeastern China, 3.0% [25], while it is lower than the seroprevalence of 52.6% using MDAT and 56% with ELISA from Nazareth, Ethiopia [19].In goats, the percentage ofT. gondii infection is in consistence with the reported prevalence of 24.1% using MDAT and 25.9% by ELISA in Nazareth, Ethiopia [18], and 27.9% in Thailand [26] and higher than 11.6% [16] and 15.48% [27] in Central Ethiopia. However, on the contrary, it was lower than the reported prevalence of 35% in Debre Berhan, Ethiopia [16], and 44.3% in Egypt [28].The seroprevalence ofT. gondii infection in cattle observed in this study is comparable with the reported seroprevalence of 6.6% from Central Ethiopia [16], 15.77% in Iran [29], and 13% in Tanzania [11]. However, the current value is higher than the reported seroprevalence of 2.68% in Brazil [30] and 3.92% in Algeria [31]. In contrast, it is lower than that of the determined seroprevalence of 22.3% in Thailand [32], 32% in Sudan [12], and 43.5% in Pakistan [33].In the present study, the proportion of camels positive for anti-T. gondii antibodies (14.4%) at animal level is in consistence with the proportion in Sudan (20%) [12], while it is higher than that of 3% in China [34].The flock/herd level seroprevalence in sheep, goats, cattle, and camels in the current study was high. The flock seroprevalence recorded in sheep is like that of the previously reported value of 70.48% in East and West Shewa zones of Oromia Region, Ethiopia [15], and 58.89% in Algeria [31]. In goats, the flock seroprevalence was higher than that of 45.17% reported by Swai and Kaaya [13] in Tanzania. The variation in seroprevalence ofT. gondii infection among domestic ruminants in the current study from those previously reported in Ethiopia and elsewhere in the world might be attributed to differences in geographical location, animal management practices, and the sensitivity and specificity of serological diagnostic tests used for detecting the infection.In this study, a significant difference inT. gondii seropositivity was observed between the two sex groups of sheep. Female sheep were 2.63 times more infected than males and those that drank from pond and pipe water sources were 4.25 and 9.57 times more infected than those that drank from mixed water sources, respectively. This finding was in accordance with that reported by Ramzan et al. [24]. The increased susceptibility of females might be associated with their lower immunologic resistance in certain periods of their lives [35]. In contrast, Silva et al. [36] and Lashari and Tasawar [37] observed that higher seroprevalence in male sheep than in females is attributed to androgen production lowering their immunity.In goats, those >1 year old were 3.45 times more infected than those ≤1 year old. Besides, goats that drank pond and pipe water had 6.03 times and 11.61 times more chance of acquisition ofT. gondii infection, respectively. Likewise, cattle that obtained drinking water from ponds and pipes were 5.60 and 10.68 times more infected withT. gondii compared with those that used other water sources. Camels > 4 years old were 2.49 times more infected compared with those ≤4 years old.The progressive increase in seroprevalence with age seen in sheep, goat, cattle, and camel indicates sustained exposure to theT. gondii infection in the environment [6, 19]. Moreover, in the present study, a significantly higherT. gondii infection was found in goats > 1 year old and camel > 4 years old compared with the remaining age groups. This may be due to the fact that animals that lived longer might be more likely exposed to the infectious agent from different sources [19, 26].The observed increased risk of infection in sheep, goats, and cattle that were given pipe water might be explained by the presence of several roaming cats capable of contaminating the pipe water source with infectiveT. gondii oocysts. Silva et al. [36] and Tenter [38] suggested that few cats are sufficient to contaminate a wide field area in short time, since one infected cat sheds millions of oocysts. In addition, watering troughs and the storage of animal feeds stored outdoor which are accessible to cats might be contributed to the heightened seropositivity ofT. gondii infection among domestic ruminants.Consistent with the present finding, Gebremedhin et al. [15] reported high risk of infection in sheep given pipe water. However, contrary to our finding, Pinheiro et al. [5] observed increased chances of infection in animals living on properties with running water systems than those living with stagnant water sources. The similarities and differences might be attributed to the resemblance and variations in agroecological situation and rate of contamination of the water properties by infective oocysts.


## 5. Conclusion

It could be concluded thatT. gondii infection is more common and widespread among domestic ruminants found in the study area. Sex, age, and water source act as risk factors forT. gondii infection. Thus, the higher seroprevalence encountered in these animal species used as a food source revealed the potential risk ofT. gondii infection presented to people through consumption of their meat. Therefore, awareness of people on ways of transmission and prevention ofT. gondii infection should be raised through education and further study should be conducted to explore the impact of the disease on food animal production.



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*Source: 4263470-2018-05-20.xml*