A brief report on the nature and epidemiology of T. gondii infection is firstly presented. The importance of the specific IgG avidity test and polymerase chain reaction (PCR) for toxoplasmosis is discussed, along with their significance and importance as auxiliary methods for determining the most likely time for the initial infection by this coccidian and for defining the therapeutic strategy. Lastly, practical comments are made in relation to the classical therapeutic regimens, with special attention to the indications for fetal treatment, when this is necessary. 1. Introduction Toxoplasmosis is an infection caused by the intracellular protozoon T. gondii, for which the primary host is cats. It is known that approximately 10% of all cats are contaminated by T. gondii. Sexual reproduction of this parasite takes place in the intestinal environment of cats, and the oocysts produced are eliminated together with the feces. The oocysts remain viable in the external environment for up to one year. Within this setting, T. gondii contaminates secondary hosts through these hosts’ contact with sand, foods, or plants that have been contaminated by the oocysts. After ingestion of the oocysts, the oocyst wall becomes thinned by the digestive juices, thereby leading to release of sporozoites into the intestinal lumen. The sporozoites rapidly invade the intestinal epithelium, though the vascular endothelium. At this stage of the evolution, they are transformed into tachyzoites, which are the invasive form of the parasite. Through tachyzoite dissemination, the parasite will lodge in a wide variety of tissues in the secondary host, in which large numbers of cysts that are rich in bradyzoites are produced. The secondary hosts are commonly humans, rodents, birds, crustaceans, domestic animals, and practically all other warm-blooded animals, which explains why consumption of raw or undercooked meat can contaminate other hosts with bradyzoites from tissue cysts. Ingestion of sporozoites occurs mainly through eating poorly washed fruits or vegetables, doing gardening, coming into contact with children who were playing on the ground or on sand, and so on [1]. Data in the literature consistently draw attention to the importance of proper guidance regarding the commonest means of becoming infected with T. gondii, with the aim of preventing this event within the pregnancy cycle and the possible harm done to the fetus [2, 3]. A study conducted in the “Economic Research Service” in the United States concluded that approximately half of the cases of toxoplasmosis occurred due to
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