Toxoplasma gondii, the causative agent of toxoplasmosis, is a widespread parasite found in most parts of the world and can infect any warm-blooded animal. The prevalence of infection in humans varies widely, from 7% in Navajo Indians to 94% in Guatemala, with an average of about 30% in England. Infection occurs when trophozoites penetrate and multiply in host cells, leading to the formation of tissue cysts that persist for years. Transmission can occur through various routes, including transplacental transfer, consumption of undercooked meat, and contact with infected cat feces containing oocysts. Clinically, toxoplasmosis can manifest as congenital or acquired infections. Congenital toxoplasmosis can cause fetal infection, leading to abortion, miscarriage, stillbirth, or live-born infants with varying degrees of severity. Ocular involvement is common, often affecting the choroid and retina, and can result in visual impairment. Neurological involvement, including meningoencephalitis, is also possible. Acquired toxoplasmosis can present as lymphadenopathy, involvement of other organs, or generalized illness. Treatment with combinations of sulphonamides and pyrimethamine has been effective, particularly in controlling active ocular infections and preventing congenital transmission. However, lymphadenopathic toxoplasmosis is challenging to treat beyond controlling fever. Epidemiological studies suggest that congenital toxoplasmosis occurs in a significant proportion of pregnancies, and the role of oocysts from cats in human infections is under investigation. Antibody tests are essential for diagnosis, but a safe, simple, and reliable test is still needed.Toxoplasma gondii, the causative agent of toxoplasmosis, is a widespread parasite found in most parts of the world and can infect any warm-blooded animal. The prevalence of infection in humans varies widely, from 7% in Navajo Indians to 94% in Guatemala, with an average of about 30% in England. Infection occurs when trophozoites penetrate and multiply in host cells, leading to the formation of tissue cysts that persist for years. Transmission can occur through various routes, including transplacental transfer, consumption of undercooked meat, and contact with infected cat feces containing oocysts. Clinically, toxoplasmosis can manifest as congenital or acquired infections. Congenital toxoplasmosis can cause fetal infection, leading to abortion, miscarriage, stillbirth, or live-born infants with varying degrees of severity. Ocular involvement is common, often affecting the choroid and retina, and can result in visual impairment. Neurological involvement, including meningoencephalitis, is also possible. Acquired toxoplasmosis can present as lymphadenopathy, involvement of other organs, or generalized illness. Treatment with combinations of sulphonamides and pyrimethamine has been effective, particularly in controlling active ocular infections and preventing congenital transmission. However, lymphadenopathic toxoplasmosis is challenging to treat beyond controlling fever. Epidemiological studies suggest that congenital toxoplasmosis occurs in a significant proportion of pregnancies, and the role of oocysts from cats in human infections is under investigation. Antibody tests are essential for diagnosis, but a safe, simple, and reliable test is still needed.