Toxoplasma gondii infection in pigs in Serbia
Toxoplasma gondii is a common zoonotic intracellular parasite in livestock raised for human consumption and is a public health concern. The mode of transmission is ingestion, and meat is considered to be a major vehicle for human and animal infection. As T. gondii is environmentally transmissible, other important vehicles in particular for animals include vegetation, soil and water. The seroprevalence of T. gondii infection in pigs is Serbia has been determined in several studies over the past two decades. It has been established that it varies considerably, primarily based on husbandry, with strictly to mostly indoor animals having a lower prevalence (below 20%) than animals raised outdoors, where prevalence exceeds 60%. Experimental data suggests that different genotypes of the parasite vary in virulence, but the significance of virulence in terms of pathology and disease manifestations is still being investigated. Genotypes of T. gondii isolated from pig tissues in Serbia to date are ToxoDB#1 (archetype II) and ToxoDB#2 (archetype III). Archetype II is predominant and, based on historical reports and recent findings, low to intermediately virulent. The virulence phenotype and mechanisms of archetype III, however, have not been extensively studied, but recent data suggests that its virulence may vary considerably. This review will also summarize the current knowledge regarding the virulence of archetypes II and III and evaluate it in the context of the pig host.