Comparison of a Commercial Enzyme-Linked Immunosorbent Assay (ELISA) with the Modified Agglutination Test (MAT) for the Detection of Antibodies against Toxoplasma gondii in a Cohort of Hunting Dogs

SIMPLE SUMMARY: Toxoplasmosis is a zoonotic disease that has serious consequences for immunocompromised individuals, in particular for the fetus during primary infection in pregnant women. The parasite responsible, Toxoplasma gondii, can infect all warm-blooded animals, and studies on antibodies against the parasite in their blood can give a good estimate of its burden in the environment and the risk for human infections. This is less studied in dogs than in other animal species, especially in northern African countries, despite evidence that they can be a potential source of human contamination. The study reported here compared two different methods to assess the presence of antibodies against T. gondii in a cohort of hunting dogs from northern Algeria, as these dogs are in close contact with wildlife and humans, in both rural and urban environments. The results of this study show that about 37% of hunting dogs are infected by T. gondii and that both tests can be used for this diagnostic purpose. This work also highlights the importance of this kind of study in companion animals to assess infectious risk of T. gondii for human populations. ABSTRACT: Toxoplasmosis is a zoonotic disease, caused by the protozoan Toxoplasma gondii, affecting most warm-blooded animals. Assessing the seroprevalence of T. gondii in different animal species gives a good estimate of the global circulation of the parasite and the risk for human infections. However, the seroprevalence of T. gondii in dogs is not studied as much as other species, despite their close contact with wildlife and humans in rural or urban environments and evidence that dogs can also be a potential source for human contaminations. A commercial enzyme-inked immunosorbent assay (ELISA) kit to detect anti-T. gondii antibodies in sera of hunting dogs potentially naturally infected, was compared to the modified agglutination test (MAT), used as the reference method. The ELISA presented a sensitivity of 76.5% (CI 95%: 60.0–87.6) and a specificity of 87.7% (CI 95%: 76.7–93.9) and a substantial agreement with the MAT for the detection of canine anti-T. gondii antibodies. Both tests can therefore be used widely for epidemiology studies on T. gondii infections in dogs. With a mean seroprevalence of T. gondii infection in hunting dogs from northern Algeria of 36.8% (CI 95%: 34.9–38.7), this study also highlights the importance of T. gondii seroprevalence studies in companion animals to assess infectious risk for human populations.