Introduction

The Brazilian national sheep flock is approximately 17 million head, and 56.7% of this effective are concentrated in the Northeastern region. In the State of Paraiba, sheep farming has economic importance, and this state has a headcount of 433,032 animals distributed in 19,826 farms (^{IBGE, 2010}). In this context, epidemiological investigations of infectious and parasitic diseases are of relevance. Among these diseases, toxoplasmosis can be highlighted, given that this is an important cause of abortions among sheep (^{DUBEY, 2010}). Furthermore, the fact that this disease is a widespread zoonosis has to be taken into account.

Toxoplasma gondii is a protozoan parasite with worldwide distribution that can infect a wide range of animal species, including sheep. It has an indirect life cycle with felids as the definitive hosts (^{DUBEY, 2010}). In sheep, T. gondii has been recognized as one of the main causes of infectious ovine abortion in New Zealand, Australia, the United Kingdom, Norway and the United States (^{DUBEY & BEATTIE, 1988}; ^{DUBEY, 2010}). This agent is estimated to infect between 4% and 77% of the human population (^{TENTER et al., 2000}). Although not normally a significant problem for healthy individuals, T. gondii infection can be life-threatening to infants infected congenitally and to immunosuppressed patients (^{CHINTANA et al., 1998}). In animals, T. gondii infection not only results in significant reproduction losses and, hence, economic losses, but also has implications for public health, since consumption of infected meat or milk can lead to zoonotic transmission (^{DUBEY, 2010}).

To date, there have not been any reports of epidemiological investigations relating to toxoplasmosis in sheep in the State of Paraiba, Northeastern Brazil. Therefore, the aims of this survey were to determine the flock-level and animal-level prevalences and to identify the risk factors for T. gondiiinfection among sheep in the State of Paraiba, using a planned sampling.

Materials and Methods

Results and Discussion

Among the 63 flocks, 28 (44.4%) presented at least one seropositive sheep, and among the 540 sheep used, 60 were seropositive for T. gondii, thus resulting in a prevalence of 11.1% with antibody titers ranging from 64 to 2,048. ^{Sakata et al. (2012)} found a seroprevalence of 56.94% among sheep in the municipality of Lages, State of Santa Catarina. This high prevalence, in comparison to that obtained in the present study, may be explained by the high humidity of the Lajes region, with greater and more regular rainfall, which may contribute towards higher viability among T. gondii oocysts in the environment. On the other hand, ^{Pereira et al. (2012)} and ^{Andrade et al. (2013)} found prevalence rates of 16.9% and 26.29% among sheep in the States of Pernambuco and Rio Grande do Norte, respectively, which are both located in the semiarid region of Brazil.

Even though the prevalence of seropositive animals was low, there was at least one seropositive animal in 44.4% of the flocks. This demonstrates that this agent is spread in the region. In this context, it should be noted that the sheep-rearing profile in this region consists of extensive and semi-intensive management systems, in which the animals are set free during the day and are gathered into rustic pens at night, lacking basic infrastructure, with inadequate hygiene practices. This demonstrates that there is a need to apply appropriate technologies to the realities of sheep farming in the semiarid region. Absence of technification, such as practicing regular cleaning of the installations and reproductive management during the postpartum period, may facilitate the contact with T. gondiioocysts present in the environment (^{TENTER et al., 2000}).

In the risk factor analysis, the variables of purpose of rearing (P= 0.164), technified rearing (P = 0.066), flock size (P = 0.066) and occurrences of abortions (P = 0.081) were selected from the univariable analysis (Table 1). In the multivariable analysis, the variable of flock size > 25 animals was identified as a risk factor (odds ratio = 3.2; 95% CI = 1.09 – 9.34; P = 0.033). This indicator reinforces the argument that the risk of introduction and spreading of diseases and, consequently, occurrence of economic losses in sheep production is greater when the flock size is larger, however, variables related to herd size are not liable of correction, and in this case, an adequate sanitary planning assumes an important role as a control measure.

Regarding occurrences of abortions, although this variable was not associated with T. gondii prevalence in the multivariable analysis, the frequency of positivity was greater in flocks with no reports of abortions (53.7%) than in flocks with history of abortions (27.3%) (Table 1), with an odds ratio of 3.09 (95% CI = 1.01 – 9.48) (data not shown). This situation raises the awareness that is a need of analysis in which the matter of sub-notification of abortions can be taken into consideration, particularly with regard to extensive rearing systems. The predominance of extensive systems under semiarid conditions, in association with precarious management practices and absence of a zootechnical register, contribute towards ineffective monitoring of events relating to reproductive problems. This may make it difficult to evaluate the productive and economic performance.

Conclusion

We concluded that T. gondii infection is spread among sheep in the State of Paraíba, Northeastern Brazil, and our findings suggest that the implementation of adequate sanitary planning is necessary to avoid the spreading of the infection and, consequently, occurrence of economic losses in sheep production.