Development and evaluation of a modified agglutination test for diagnosis of Toxoplasma infection using tachyzoites cultivated in cell culture

Toxoplasma gondii is a zoonotic protozoan parasite that can cause significant disease in most warm-blooded animals, including humans. Surveillance testing of human and animal populations is essential to estimate disease prevalence, assess food safety risks and establish control programmes. Serological tests are the most practical methods to detect the prevalence of infection in a broad range of host populations. The modified agglutination test (MAT) is a sensitive serological method to detect Toxoplasma IgG antibodies in livestock and wild animals. An in-house MAT was developed using tachyzoites produced by in vitro cultivation instead of traditional propagation in murine peritoneal cavity. The assay was evaluated using samples of serum and/or meat juice from pigs and cats experimentally infected with T. gondii. Samples were also tested by a commercially available MAT kit. Comparative analysis of test results from serum and meat juice samples showed excellent agreement between the in-house MAT and the commercial MAT. Serum and/or blood samples from naturally infected cats, sheep, and 20 wildlife host species were also tested by the in-house MAT, with overall results comparable to those obtained using the commercial MAT kit. Therefore, this new MAT is an efficient and convenient method for testing a variety of terrestrial and aquatic domestic or wild host species for T. gondii.