Seroconversion to Brucella spp. and Toxoplasma gondii in Sheep and Goats in Dohuk Province, Iraq and Its Association with Pregnancy Loss

Simple Summary Brucellosis and toxoplasmosis cause economic losses in small ruminants, notably through abortions. Both Brucella melitensis and Toxoplasma gondii are important zoonotic agents with infection of the former arising from contact with infected small ruminants or their products and the latter through ingestion of tissue cysts in undercooked/raw meat products of livestock or from oocysts from cats. In Iraq, factors which influence reproductive failure in small ruminants are mostly unknown; however, of the many endemic diseases present, brucellosis and toxoplasmosis are considered important in reducing reproductive output and productivity. This study is part of an integrated research project aiming at understanding the epidemiology of reproductive diseases in small ruminants in northern Iraq. We present in this work a prospective cohort study aiming to determine the incidence risk of seroconversion to Brucella and Toxoplasma and the association of seroconversion with the reproductive outcome in pregnant sheep and goats in Dohuk, northern Iraq. In this study, sera from 240 small ruminants (192 sheep and 48 goats) belonging to 12 farms in Dohuk Province, northern Iraq, were collected on two occasions to investigate the incidence risk of seroconversion to Brucella spp. and Toxoplasma gondii. All selected animals were confirmed pregnant (approximately 2 months pregnant) by ultrasound examination at the time of the first blood collection. A second ultrasound examination and blood sampling were undertaken two months after the initial scanning/sampling. Antibodies to Brucella were tested using the Rose Bengal Test (RBT) and an indirect enzyme-linked immunosorbent assay (iELISA), and the results were interpreted in series. The Latex Agglutination Test (LAT) and an indirect enzyme-linked immunosorbent assay (iELISA) were also used in series to confirm the presence of antibodies to T. gondii. The seroprevalence for Brucella and Toxoplasma increased significantly between the two sampling times (p = 0.0003 and 0.03 in first and second sampling, respectively). The incidence risk of seroconversion to Brucella over the two months was 10.6% (95% CI: 6.9-15.3) and 7.3% (95% CI: 4.3-11.6) for Toxoplasma. Animals that seroconverted to Brucella were 2.9 times more likely to lose their pregnancy (95% CI: 1.6-5.5) than animals that remained seronegative; however, seroconversion to Toxoplasma had no significant impact on loss of pregnancy. This study is the first reported investigation on the association of seroconversion to Brucella and Toxoplasma with the reproductive outcome of pregnant sheep and goats in northern Iraq. Brucellosis and toxoplasmosis continue to negatively impact small ruminants' reproductive performance and compromising food security in Iraq. It is hoped that this study will assist the development of a better-informed economic model to estimate Brucella and Toxoplasma burden in small animals in northern Iraq, and such a model could be used to validate the impact of various potential intervention programs in.