Toxoplasma gondii is a protozoan that causes the illness toxoplasmosis. Numerous species of birds and mammals carry T. gondii, and human infections are frequent. T. gondii infection affects 22.5% of people aged 12 and older, according to the Centers for Disease Control and Prevention (CDC), however immunocompromised individuals usually show no symptoms. Domestic cats serve as the primary infection carriers since they are the only known definitive hosts for the sexual stages of T. gondii. The parasite’s oocysts are excreted by infected cats, and people often get these oocysts through coming into contact with cat waste, in litter boxes, or in garden beds where outside cats urinate.
The life cycle of T. gondii is complex and involves several hosts. When unsporulated oocysts are shed in the cat’s feces, the T. gondii life cycle starts. The environment requires these oocysts to sporulate for 1 to 5 days before they become infectious. Birds and rodents serve as intermediate hosts, becoming infected after consuming soil, water, or plant matter contaminated with the pathogenic oocysts. After being consumed, the oocysts change into tachyzoites that settle in the muscle and neural tissue of the bird or rodent and grow into tissue cysts. Cats who consume birds and rodents with tissue cysts may acquire the infection. Cats and other animals may potentially get the disease by consuming sporulated oocysts that are present in the environment. It’s interesting to note that Toxoplasma infection seems to have the power to alter the host’s behavior. Mice with toxoplasma infection no longer fear cat pheromones. Thus, they become easier prey for cats, promoting the parasite’s transfer to the cat ultimate host.
Human toxoplasma infections are relatively common; however, the majority of infected individuals show only mild or subclinical symptoms. According to some research, the parasite may be capable of influencing an infected person’s personality and psychomotor performance in a manner similar to how it alters behavior in other mammals. When symptoms do develop, they frequently resemble those of mononucleosis and are typically minor. Asymptomatic toxoplasmosis, nevertheless, can occasionally cause issues. Cysts can linger for years in a number of different human tissues. Immunocompromised individuals may experience the reactivation of these dormant infections following transplantation, cancer treatment, or the onset of an immunological illness like AIDS. Because the immune system is unable to stop T. gondii from growing in bodily tissues in AIDS patients with toxoplasmosis, these cysts can result in encephalitis, retinitis, pneumonitis, cognitive problems, and seizures that can ultimately be deadly.
Tachyzoites, which can spread to the developing fetus through the placenta, increase the risk of toxoplasmosis during pregnancy. The severity of the mother’s illness, the placenta’s damage, the fetus’ gestational age at the time of infection, and the organism’s virulence all affect how much toxoplasmosis harms the developing fetus. Congenital toxoplasmosis can cause central nervous system damage, which can show up as mental retardation, deafness, or blindness. It frequently results in fetal loss or premature delivery. The CDC advises pregnant women to take extra precautions when cooking meat, gardening, and taking care of pet cats. The most common method for diagnosing toxoplasmosis infection during pregnancy is serology, which includes TORCH testing. By employing molecular techniques like PCR to find T. gondii DNA in amniotic fluid, congenital infections can also be diagnosed.
Observing tissue cysts in tissue samples can help doctors diagnose toxoplasmosis in adults. Giemsa- or Wright-stained biopsy samples may show tissue cysts, and infection can also be verified using lumbar puncture, magnetic resonance imaging, and CT scans.
The strongest first-line protection against toxoplasmosis is prevention of infection. After handling raw meat, dirt, or cat litter, you should thoroughly wash your hands. You should also avoid eating any veggies that could have been contaminated with cat excrement. When cooking, the internal temperature of any beef should be 73.9–76.7 °C (165–170 °F).
For Toxoplasma infections, the majority of immunocompetent individuals do not need therapeutic intervention. Pyrimethamine and sulfadiazine can be used to treat immunocompromised individuals, newborns, and pregnant women, with the exception of the first trimester of pregnancy, when these medications have the potential to result in birth abnormalities. Because spiramycin does not cross the placenta, it has been used safely to prevent transmission in pregnant women with primary infection during the first trimester.
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