Seroprevalence of toxoplasma gondii and brucella abortus in dairy animals from the Sudan: special emphasis to their serological co-existence

Toxoplasmosis and brucellosis are the most common zoonotic food borne diseases worldwide. The abortion caused by these agents is one of the major causes of socioeconomic losses in human and livestock. We thus conducted a cross-sectional study during October 2012 to April 2014 to determine the seroprevalence and the coexistence of Toxoplasma gondii and Brucella abortus in dairy cattle and the co-herded camels, sheep and goats in the Khartoum State using different serological techniques. The study revealed over all seroprevalence of 94.9% at herd level and 63.2% at individual level. T. gondii and B. abortus seroprevalence were 46.2% and 22.7% respectively. Seroprevalence of these zoonosis showed highly statistically significant (p<0.01) differences among different localities and different animals species. Antibody to T. gondii was found to be more prevalent in Sheep, goats and camels respectively while antibody against B. abortus was more prevalent in cattle and camels. Mixed antibodies against the two zoonotic agents were detected in almost all seropositive herds (99.1%). Only one seropositive herd (0.9%) revealed a single Brucella abortus infection. Mix-infection was observed in 16.2% out of all seropositive animals. The univariate analysis of different localities and different animal species showed significant (p<0.01) association with mix-infection seropositivity. Increasing odds ratios without significant (p>0.05) associations were observed in the multivariate analysis of districts and animals species (odds=2.588, CI 95%) for cattle and (odds=2.200, CI 95%) for camels compared to goats as reference. Generally, the present results were the first comprehensive data explaining the serological co-existence of T. gondii and B. abortus as zoonotic organisms in Sudanese food animals. We came to conclude that, the exposure to these organisms as well as their co-infection may play a significant role in the economic losses in dairy farm industry in the country. Moreover, the great public health importance of T. gondii, B. abortus and their co-existence could not be neglected. Further studies to elucidate their socio-economic consequences in man and his livestock are recommended. ـــــــــــــــــــــــــــــــــــــــــ


INTRODUCTION
Food security is one of the major global challenges we face.Brucella abortus (B.abortus) is an important zoonotic abortifacient agent among dairy animals.However, nowadays the most common zoonosis, Toxoplasma gondii (T.gondii) is steadily reported as parasitic abortifacient from farm animals

Study Area
Khartoum State (fig.1), the capital State of the Sudan is the smallest state by area (22,142 km 2 ), but it is the most populous (5,274,321 in 2008 census).The Sudan dairy industries of different production systems are concentrated in this State (MLFR 2014).

Study Population
The study involved a total of 1447 adult animals, including 1190 heads of dairy cows, 60 shecamels, 97 sheep and 100 goats from 177 dairy herds selected at random from various dairy clusters in the seven localities of the State (fig.1).

Samples
Taking the advantage of blood drawing for research project on Brucellosis blood for serum was collected from the jugular vein of the above mentioned animals during October 2012 to April 2014.Their sera were separated and cryo-preserved in -20ºC until examined.

Statistical analysis
Differences in the seroprevalence and the coexistence of these agents among the investigated areas and animal species were analyzed by Chi-square test.The differences were considered statistically significant when (p≤0.05).The same test was used to analyze the association between their seropositivity (Univariate analysis) before multivariate analysis was used (Logistic Regression).The overall fit of the logistic regression models was assessed using Hosmer-Lemeshow goodness of fit statistics.All statistics were performed using SPSS version 17.0 statistical package.

Mapping
Maps were produced using Arc GIS version 10.2.2 (ESRI, Redlands, California) to show the study area and the distribution of the prevalence rate in different localities of the State.

RESULTS
The overall seroprevalence of T. gondii or/and B. abortus infections at herd level was 94.9% (Table 1).Antibody against T. gondii and B. abortus was detected in 92.7% and 65.6% of the tested herds respectively.The minimum and the maximum within herd prevalence rate were presented in table (2).The majority of the herds that infected with T. gondii recorded more than 50% prevalence rate, while the herds having B. abortus recorded less than 50% prevalence rate (Table 3).At individual level, the overall seroprevalence was 63.2% (Table 3).
As presented in table (4), T. gondii and B. abortus seroprevalence were 46.2% and 22.7 respectively.Highly statistically significant (p<0.01)differences were reported among animal species.Mixinfection was significantly higher (p<0.05) in cattle and camels followed by goats and sheep (Table 4).The details of co-existence of T. gondii and B. abortus was presented in table ( 5), where mix-infection was detected in 140 (16.2%)out of 865 seropositive animals.
As presented in table 6, the univariate analysis showed highly significant (p<0.01)association between the mix-infection of T. gondii and B. abortus seropositivity and the different localities (p=0.000) and different animals species (p=0.000).In the multivariate analysis, increasing odds ratio were observed in Khartoum (odds=1.444,95% CI=0.566 -3.689) and Khartoum North (odds=1.576,95% CI= 0.718 -3.459) districts, but without significant association (p=0.052).Cattle (odds=2.588,95% CI=0.848 -7.901) and camels (odds=2.200,95% CI= 0.204 -23.736) are more susceptible to the mix-infection than sheep and goats (Table 7).Because of the contradiction reports in cattle toxoplasmosis (Dubey 1995) our cattle samples were retested using ELISA to support the results of the screening test (LAT).These results together with the known feeding habits in the Sudan (eating and drinking raw meat and unpasteurized milk), put people under high risk of getting infected with these serious zoonotic diseases.In our recent report (Ibrahim et al., 2014a), it was stated that dairy animals with reproductive problems were usually sent to slaughter house for human consumption.Generally, the authors believe that the results of this study may provide the first comprehensive data explaining the co-existence of T. gondii and B. abortus in dairy industry in the Sudan for their economic and public health concern.

CONCLUSION
In conclusion, Co-existence of T. gondii and B. abortus is frequently occurring in food animals and their public health importance could not be neglected.Further in-depth study on Sudanese people and their livestock is recommended.

(
Seri et al. 2003; Figliuolo et al. 2004; Ortega-Mora et al. 2007; Weiss and Kim 2007).Reports on Coexistence of T. gondii with Neospora caninum was more available worldwide (Dubey et al. 1998; Huong et al. 1998; Hilali et al. 1998; Helmick et al. 2002).However, studies on T. gondii and B. abortus coexistence are spares (Yildiz et al. 2009).Human and animal brucellosis was extremely investigated in the Sudan (Angara 2005; Angara et al., 2009).However, meager data on toxoplasmosis was available in the Sudanese people (Abd Elhameed, 1991; Adnan, 1994; Elnahas et al., 2003; Maha et al., 2012; Khalil et al., 2013; Abdel-Raouff and Elbasheir 2014) and animals (Seri et al. 2003, Khalil and Elrayah 2011; Abdel Hafez 2013; Elfahal et al., 2013; Ibrahim et al., 2014a).Toxoplasmosis is an opportunistic infection.Antibodies to T. gondii are detected more frequently in sick (Immunosuppressed) animals and any complications of primary disease (Svoboda et al. 1988; Svoboda et al. 1998).Toxoplasma gondii infection has become a major public health concern in recent years due to the ravaging HIV/AIDS pandemic (Dubey 2004; Lindstrom et al., 2006; Negash et al., 2008).Both, T. gondii and B. abortus are transmitted to human through eating or drinking raw/undercooked or unpasteurized milk of infected animals (Tenter 2009; Tenter et al., 2000).Thus we aimed to determine the seroprevalence, mix-infection and to interrogate the association of T. gondii and B. abortus seropositivity in dairy cows and the co-herded camels, sheep and goats in dairy farms from the Sudan.

Fig. 1 :
Fig. 1: The Sudan map showing the Khartoum State Localities (the area of the study in red colour). Fig3:

Table 1 :
Overall Seroprevalence of T. gondii or/and B. abortus in dairy farms from the Khartoum State, Sudan.

Table 2 :
Seroprevalence of T. gondii and B. abortus in dairy herds from the Khartoum State, Sudan.

Table 4 :
Seroprevalence of Toxoplasma gondii and Brucella abortus in different dairy animals from the Khartoum state, Sudan.

Table 5 :
Distribution of Mix-infection among over all seropositive dairy animals from the Khartoum state, Sudan.

Table 6 :
Results of Univariate association of Risk factors with T. gondii and B. abortus Mix-infection in Dairy animals from the Khartoum state, Sudan.

Table 7 :
Results of Multivariate association of Risk factors with T. gondii and B. abortus Mix-infection in Dairy animals from the Khartoum State, Sudan.Efforts aimed at reducing the impact of zoonotic diseases in human and his livestock will be vital to improve people livelihood and production efficiency.The majority of abortion cases in dairy farms originate from infectious agents including T. gondii and B. abortus (

Ortega-Mora et al. 2007).
The present study revealed that dairy animals in the Sudan were widely exposed to T. gondii and B. abortus.Similar results were reported by Yildiz et al.(2009).In agreement with the later authors, T. gondii was found to be more prevalent than B. abortus.Among all seropositive animals 16.2% were co-infected with both T. gondii and B. abortus.