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Toxoplasmosis in Sheep from Kurdistan Province, Iran



M. Khezri, B. Mohammadian, K. Esmailnia and O. Khezri
 
ABSTRACT

Toxoplasmosis is one of the most common parasitic zoonosis in Iran. The causative agent, Toxoplasma gondii, uses a wide range of warm-blooded intermediate hosts in its life cycle, including sheep. Sheep is an important domestic animal in the Kurdistan province of Iran due to its minimal rearing and maintenance costs and production of meat, milk and wool. This study was conducted on the seroprevalence of T. gondii infection in sheep from different regions of Kurdistan province between December 2008 and September 2009 and analyzed the main risk factors associated with the infection. Sera from 368 sheep were examined for anti T. gondii IgG antibodies by indirect enzyme-linked immunosorbent assay ELISA test. According to the results, the seropositive rates of sheep were 21.74%. Though, the southern with 44% and western with 13.25% had the highest and lowest infection rates, respectively; the differences between geographical locations were statistically significant (p<0.05). Although, the specific antibodies were detected in 20.87% of males and 22.13% of female's sheep but there were no significant differences between two genders. On the other hand, no significant differences were observed between age groups. These results indicate that the seroprevalence of T. gondii infection in sheep is relatively high.

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M. Khezri, B. Mohammadian, K. Esmailnia and O. Khezri, 2012. Toxoplasmosis in Sheep from Kurdistan Province, Iran. Asian Journal of Animal Sciences, 6: 182-188.

DOI: 10.3923/ajas.2012.182.188

URL: https://scialert.net/abstract/?doi=ajas.2012.182.188
 
Received: November 05, 2011; Accepted: April 03, 2012; Published: May 21, 2012

INTRODUCTION

Toxoplasmosis is worldwide-established parasitic zoonosis capable of causing clinical manifestations such as abortion, stillbirths, fetal death or birth of weak, non-viable animals (Tenter et al., 2000; El-On and Peiser, 2003). The parasite has a worldwide distribution and it is mainly transmitted by food contaminated with Oocysts dispersed by definitive hosts, cats and other felines, uncooked meat containing tissue cysts or non-pasteurized milk containing tachyzoites stages and transplacentally (Sacks et al., 1982; Dubey, 1996; Jittapalapong et al., 2005; Sukthana, 2006; Clementino et al., 2007). Toxoplasmosis is a parasitic disease that causes serious reproductive problems and economic losses to the sheep industry all over the world (Buxton et al., 2007).

Sheep are important to the economy of many countries because they are a source of food for humans sheep are commonly infected with the protozoan parasite, Toxoplasma gondii. Infection with the parasite may cause early embryonic death and resorption, fetal death and mummification, abortion, stillbirth and neonatal death. Severity of infection is associated with the stage of pregnancy at which the ewe becomes infected, the earlier in gestation, the more severe the consequences. Infected sheep meat is a source of T. gondii infection for humans and carnivorous animals. Most sheep acquire T. gondii infection after birth and less than 4% of persistently infected sheep transmit the parasite vertically to the next generation (Dubey, 2009).

In a review by Tenter et al. (2000) of surveys carried out in Europe, values range from 4 to 92% in farmed sheep. Antibodies to T. gondii were found in (22.0%) lambs and in (65.6%) ewes slaughtered in Haute-Vienne district (Dumetre et al., 2006).

In animals, T. gondii infection not only in significant reproductive and hence economic losses but also has implications for public health since consumption of infected meat or milk can facilitate zoonotic transmission. T. gondii can be transmitted directly by animal-human contact or through contact with contaminated feces, soil or herbage, it can also be transmitted through contaminated food or water (Jittapalapong et al., 2005).

In Iran, studies have shown the presence and importance of T. gondii, especially in sheep and goats (Ghazaei, 2005; Hamidinejat et al., 2008; Hoghooghi-Rad and Afraa, 1993; Sharif et al., 2007; Zia-Ali et al., 2007).

Since, there is little information on the prevalence of infection in Kurdistan province (west Iran) the objectives of the present study were, therefore, to investigate the prevalence of T. gondii and its relationships between age, sex and various geographical regions.

MATERIALS AND METHODS

Kurdistan covers a territory of 28,203 km2, all sample areas were between 750 and 3300 m above sea level and rainfall ranges from 250 to 800 mm year-1. Kurdistan has three types of weather. Southern and central parts of the temperate climate and average rainfall of 450 mm. Eastern and northern part shave cold and relatively dry climate, with rainfall less than 300 mm. Western part is cold and wet climate and average rainfall is 700-800 mm. A total sheep of different ages (>6 months old, 6 = 18 months old and <18 months old) and sex from various locations in the Kurdistan province were selected for study. Blood samples were obtained from 386 sheep (115 male and 253 female) between December 2008 and September 2009 from the various geographical regions of Kurdistan province, Iran. Sera were extracted from 5 mL venous blood samples, by centrifugation at 2000 g for 10 min and were stored at -20°C prior to testing. Sheep IgG antibodies against T. gondii were tested using an enzyme-linked immunosorbent assay (ELISA). The indirect ELISA (ID. VET. Innovative diagnostics, France) was performed by commercial kit. Optical densities (OD) were read at 450 nm. The results were expressed as the percentage of the mean absorbance values of sample (S) to the mean absorbance value of the positive (P) control sample provided with the diagnostic kit. The resultant S-P ratio was expressed as a percentage (S/P %). According to the manufacturers recommendation, sera with S/P% = 40% should be regarded as negative, between 40 and 50% as doubtful, between 50% = and <200% as positive and = 200% as strong positive.

Statistical analysis: The Chi-squared test was used for statistical analysis using SPSS, version 11.5, p<0.05 was considered significant.

RESULTS

Using the cELISA, from 386 tested samples, IgG prevalence of toxoplasmosis among sheep was 21.74% (80 sheep) in Kurdistan province, Western Iran (Table 1). The results of age, sex and different regions with positivity to T. gondii are summarized in Table 2, 3 and 4, respectively.

Table 1: Seroprevalence of Toxoplasma gondii antibodies in sheep between sexes in Kurdistan province, Iran

Table 2: Seroprevalence of Toxoplasma gondii antibodies in sheep between ages in Kurdistan province, Western Iran

Table 3: The rate of sheep Toxoplasma infection in different districts of Kurdistan, Western Iran

Table 4: The rate of toxoplasmosis infection of sheep in different cities of Kurdistan province

The highest frequency of infection was seen in Southern parts (44%, α = 0.05) and lowest Western localities (13.24%, α = 0.0.5) (Table 3). The highest prevalence (44%) was observed in Kamyaran. However, the lowest prevalence (13.16%) was found in Marivan (Table 4).

There was no difference among seropositivity for T. gondii in serum samples in all age groups (p>0.05). The seroprevalence of antibodies in female and male were 22.60 and 21.34%, respectively (p>0.05). There were variations in the rate of T. gondii-positive samples in different regions (p<0.05).

DISCUSSION

Prevalence of toxoplasmosis across the world is variable, with prevalence rates from 0 to 100% in different countries (Olivier et al., 2007; Tenter et al., 2000), depending upon their customs, traditions, life styles of the inhabitants, weather conditions, age of the animals and husbandry practice (Smith, 1999).

This study showed, the prevalence of sheep toxoplasmosis from Kurdistan province, for the first time in Iran. The seroprevalence of T. gondii in sheep was 21.74%. The rate of toxoplasmosis in our study is close to some studies (Zia-Ali et al., 2007; Sabry and Reda, 2008), respectively, who reported 20.9, 22 and 25.6% of T. gondii infection in sheep in Iran, Brazil and Egypt. However, higher incidence rates 40.4, 41.7, 50, 51.5, 52.2, 67.7, 72.6 and 84.5% were recorded by Mainar-Jaime and Barberan (2007) in Spain, Shaapan et al. (2008) in Egypt, Mason et al. (2010) in UK, Romanelli et al. (2007) in Brazil, Sanad and Al-Ghabban (2007) in Saudi Arabia, Hove et al. (2005) in Zimbabwe, Hamidinejat et al. (2008) in Iran and Klun et al. (2006) in Serbia, respectively but the lower values of 3.8, 4.3 and 11.2% detected by Sharma et al. (2008) in India, Samra et al. (2007) in South Africa, Ramzan et al. (2009) in Pakistan, respectively.

These differences in seropositivity between the different countries indicate that animals bred in these areas were exposed to different environmental contamination with T. gondii oocysts.

Further, it can be related to differences in techniques used in each study to monitor the T. gondii antibody (Ramzan et al., 2009).

The results of this study showed that, there was no significant difference in sex for antibodies to T. gondii (Table 1). This finding is similar to Bonyadian et al. (2007), Oncel and Vural (2006) and Gorman et al. (1999), While in contrast with the results of Ramzan et al. (2009), Lashari and Tasawar (2010) and Clementino et al. (2007).

However, Alexander and Stinson (1988) reported that female animals were more susceptible to be infected with T. gondii. The literature generally indicates that females have more immunity than males which may be due to the presence of estrogen in females which normally increases the immunity, while androgen in males decreases the immunity Romanelli et al. (2007). However, there are various other factors which may break down the immunity in females’ e.g., changes in sex-associated hormones, environmental factors, age, nutrition and pregnancy (Martin, 2000; Messingham et al., 2001).

This study shows no positive association between the presences of anti-T. gondii antibodies and sheep age. It is widely accepted that animals acquired Toxoplasma infection with the acquisition of age through ingestion of infective Oocysts from the environment (Ramzan et al., 2009; Figliuolo et al., 2004; Van der Puije et al., 2000) as apparently opportunity for exposure to T. gondii is routinely available. As animal ages, its cumulative likely hood for exposure increases. Due to some reasons, the age of animals is considered an important factor in determining prevalence rate of toxoplasmosis in animals (Dumetre et al., 2006; Van der Puije et al., 2000). Older sheep have a higher prevalence of toxoplasmosis than younger sheep. According to the results of the prevalence of T. gondii in present study was higher in younger animals than adult ones. This could be explained on the basis that the animals included in this age group were less resistant to T. gondii (Yung, 2000; Pawelec et al., 2002).

Seroprevalence for various regions of the province is shown in Table 3. Significant differences were indicated for seroprevalence of sheep in different areas (p<0.05). Our study showed that sheep from southern Kurdistan were at an increased risk of infection to all other regions, possibly associated with its hot and humid environment Higher prevalence rate of toxoplasmosis in warm, moist areas compared to those which are cold and dry is attributed to the longer viability of T. gondii oocysts in moist or humid environments southern Kurdistan is a warm and moist area which helps T. gondii oocysts to maintain their viability (Van der Puije et al., 2000).

The 21.74% seropositivity rate detected in 368 sheep in Kurdistan (West Iran) is lower than those reported by Bonyadian et al. (2007) and Roberts et al. (2001), in center, Sharif et al. (2007) and Youssefi et al. (2007), in North, Hamidinejat et al. (2008) in South-West and Hamzavi et al. (2007) in west, Asgari et al. (2009) in south of Iran, respectively, 29.1, 25.5, 35, 31.2, 58, 22.5 and 26.4%. These differences from different countries indicated that animals bred in these areas were exposed to different environmental contamination with T. gondii Oocysts. Furthermore, it may be due to differences of techniques used condition to monitor T. gondii antibody (Ramzan et al., 2009).

For this reason, the lower T. gondii prevalence could be attributed to the low relative humidity, cold and dry weather (Hashemi-Fesharaki, 1996).

In conclusion, the results of this study confirm the presence of Toxoplasma antibodies in sheep in Kurdistan. As some of the infected animals play a distinct role as a source of human infection, adequate management might be useful and essential to control the toxoplasmosis in the sheep herds of Kurdistan, Iran.

ACKNOWLEDGMENTS

This research was made possible by grants received from county office of Education and Research in Kurdistan- Iran. We are grateful to Mr. B. Rokhzad and Mr. H. Khanbabaie for their kind help with blood sampling.

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