Toxoplasmos
Authors: Sodré Carolina Marcia Moura , Campos Lucas Amaral , Silva Lyliane Freitas , Oliveira Sarah dos Santos , Alvarenga Janaina Sousa Campos , Alvarenga Ângela Cardoso 
Published: March 2024

Introduction: Toxoplasmosis is a disease caused by the protozoan parasite Toxoplasma gondii, which can affect several organs and systems of the human body. It is a common infection worldwide, and it is estimated that about one-third of the world's population has already been infected. Objective: The objective of this chapter is to provide information about Toxoplasmosis, including the etiological agent, forms of contamination, treatment and diagnosis, but also how to control it. Etiologic agent: Toxoplasmosis is caused by the protozoan Toxoplasma gondii, an obligate intracellular parasite. It has a heteroxenous life cycle, with two types of hosts, humans and felines being the most common. Evolutionary forms: Throughout the biological cycle, this parasite goes through three evolutionary forms: tachyzoites, bradyzoites, and oocysts. Tachyzoites are found in the acute phase of infection, while bradyzoites are found in the chronic phase and oocysts are the forms eliminated in the feces of felines. Forms of contamination of human beings: The main form of contamination of humans occurs through the ingestion of food or water contaminated with oocysts present from the feces of infected felines, especially cats. In addition, contamination can also occur through the ingestion of raw or undercooked meat from infected animals, by contaminated blood transfusion, and by vertical transmission. Biological cycle: The biological cycle of T. gondii involves two hosts: the definitive (felines) and the intermediate (humans and other animals). In the definitive host, the parasite reproduces sexually, with the formation of oocysts that are eliminated in the feces. Clinical manifestations: The clinical manifestations of toxoplasmosis vary according to the host's immune system. In immunocompetent individuals, the infection is usually asymptomatic or oligosymptomatic, and is often confused with other infectious processes. In immunocompromised individuals, such as HIV patients, transplant recipients, and cancer patients, symptoms may be more severe, especially affecting the central nervous system. In addition, congenital toxoplasmosis can lead to a number of complications in the fetus and newborn, including chorioretinitis, brain calcifications, delayed neuropsychomotor development, among others. Diagnosis: The diagnosis of toxoplasmosis is mainly made through laboratory tests, such as the detection of specific antibodies in the blood (IgM and IgG) and molecular tests to identify the parasite's DNA. Treatment: Treatment of toxoplasmosis varies depending on the severity of the disease and the patient's immune status. In mild or asymptomatic cases, treatment is usually not required. In severe cases or in immunocompromised patients, antiparasitic drugs are used, such as the combination of sulfadiazine and pyrimethamine. Infected pregnant women also need to be promptly treated. Prophylaxis: Toxoplasmosis prophylaxis involves preventive measures such as proper food hygiene, avoiding the consumption of raw or undercooked meat, washing hands after contact with cats, and maintaining daily cleaning of cat litter boxes. Conclusion: The chapter provides a comprehensive overview of toxoplasmosis, a disease caused by Toxoplasma gondii, which can cause several consequences to humans. The comprehension of the themes addressed within the chapter promotes a better coping with this parasitosis.