The infection is usually asymptomatic and results in chronicity however, a primary infection in pregnant women could cause congenital transmission and consequent serious damage to the fetus ( Jones et al., 2001). In humans, this parasite infects up to a third of the total global population ( Bigna et al., 2020 Rostami et al., 2020). Usually, the infection courses asymptomatic and becomes chronic (tissue cyst formation), except in pregnant and immunocompromised host, when it could have serious clinical implications.
IH can mainly get infected via fecal-oral transmission (ingestion of sporulated oocysts), carnivorism (ingestion of tissue cysts) or transplacental transmission (congenital infection). The extraintestinal asexual stage of the cycle (D) could occur in a wide variety of warm-blooded animals, as intermediate hosts (IH). Sporulated oocysts are infectious for both intermediate and definitive hosts. Sporogony involves meiosis (postzygotic) and sporulation. During the exogenous stage of the cycle (C), felids shed unsporulated non-infectious oocysts in their feces, but sporogony occurs in the environment within 5 days given suitable conditions of aeration, humidity, and temperature. After fertilization of haploid macrogametes by haploid microgametes, resulting in diploid (2n) zygotes formation, an oocyst wall is developed around the parasite and epithelial cells lysis permits the release of the unsporulated oocysts to the lumen. After tissue cyst wall digestion and bradyzoites release (haploids, n), several asexual replication cycles by schizogony take place before gametogony begins. Then, the enteroepithelial sexual stage of the cycle takes part in the small intestine of DH (B). Cats become infected mainly after ingestion of viable tissue cyst. Members of the family Felidae (domestic and wild cats) are the only known definitive hosts (DH) of T. gondii (top left): tachyzoites, bradyzoites (inside tissue cysts) and sporozoites (within sporulated oocysts). Toxoplasma gondii life cycle and transmission routes. In addition, globalization and trade could contribute to the inter-regional and intercontinental spread of new parasite strains ( Bertranpetit et al., 2017 Galal et al., 2019).
gondii as the fourth most important foodborne parasite in the world ( FAO and WHO, 2014). Due to its wide host range the parasite is of importance not only in public health, but also in livestock industry and wildlife management programs. gondii is present and circulates through all compartments defined in this paradigm ( Aguirre et al., 2019 Djurković-Djaković et al., 2019). Toxoplasmosis is a zoonosis of global distribution ( Robert-Gangneux and Dardé, 2012 Dubey, 2021a) and represents an excellent example of the One Health concept, since T. gondii is defined as facultative heteroxenous, with virtually all warm-blooded animals as intermediate hosts (including humans, domestic and wild mammals and birds), and members of the Felidae family acting as definitive hosts ( Dubey, 2021a) ( Figure 1). Toxoplasma gondii, the etiologic agent of toxoplasmosis, is an apicomplexan obligate intracellular protist of major medical and veterinary relevance.
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