Toxoplasma gondii infection in pregnancy

Abstract

Toxoplasmosis is caused by an intracellular protozoan, Toxoplasma gondii, which has a wide geographical distribution. The main infection routes are ingestion of cysts from raw or badly-cooked meat, ingestion of oocysts from substrates contaminated with the feces of infected felines and congenital transmission by tachyzoites. The congenital form results in a severe systemic disease, because if the mother is infected for the first time during gestation, she can present a temporary parasitemia that will infect the fetus. Many of the clinical symptoms are seen in congenitallyinfected children, from a mild disease to serious signs, such as mental retardation. Early diagnosis during the pregnancy is highly desirable, allowing prompt intervention in cases of infection, through treatment of pregnant women, reducing the probability of fetal infection and consequent substantial damage to the fetus. Conventional tests for establishment of a fetal diagnosis of toxoplasmosis include options from serology to PCR. Prevention of human toxoplasmosis is based on care to avoid infection, understanding the disease and serological exams during gestation. Pregnant women should be tested serologically from three months gestation, until one month after childbirth. Inclusion of serology for congenital toxoplasmosis along with the basic Guthrie test for PKU is of fundamental importance for early diagnosis of infection and so that treatment is initiated, in order to avoid possible sequels in the infant.

Incidence of congenital toxoplasmosis in the city of Belém, state of Pará, northern Brazil, determined by a neonatal screening program: preliminary results

“…The clinical evolution of toxoplasmosis is usually asymptomatic, but some factors, such as the genetic characteristics of the T. gondii strain and the immune status of the host, can result in serious disease, especially in immunocompromised individuals or those with congenital infection 4 .…”

Effective Diagnostic Marker for Serodiagnosis of Toxoplasma gondii Infection: New Developments and Perspectives

“…The production and appearance of each antibody isotype are correlated with the immune response after the infection, thus, the determination whether the host has got Toxoplasma infection or not can be achieved simply by monitoring the immune response especially humoral immunity. The disease symptoms are non-specific and not enough to characterize accurate diagnosis because of clinical signs mimicry between toxoplasmosis and several other infections [5,11]. Many serological tests have been designed to measure different types of antibody, which show unique increases and decreases during or after infection [12].…”

“…If an antibody is from a previous infection, no consequences for the fetus normally occur. If the infection occurs during pregnancy, the clinician should decide on administering anti-parasitic treatment to avoid disease complication in the unborn child [5,11]. Recent studies have shown that the use of IgM alone for the establishment of acute toxoplasmosis is insufficient [8].…”

“…IgG antibodies can be detected within 1-2 weeks following infectionacquisition, and normally peak within 1-2 months, and decline at various rates, but usually persist lifelong at residual titers [5,11]. High levels of this antibody indicate previous infection.…”

“…However, this antibody still has difficulty in distinguishing previous infection from a recent infection. Consequently, an auxiliary test based on the IgG avidity has been established to differentiate acute from chronic infection in an asymptomatic patient [5,11].…”