Identification
Toxoplasmosis is a rare infectious disease during pregnancy, but it can be very serious especially if the infection occurs during the first trimester of pregnancy.
The risk of maternal-foetal transmission varies according to the age of pregnancy at which primary infection occurs, being in a proportional relationship. Thus, although the risk of transmission to the fetus is lower in the first trimester, the probability that it develops signs of congenital toxoplasmosis is greater.
When it happens in the last trimester of pregnancy, in most of the cases the child will make an asymptomatic, inapparent infection. However, the untreated infection may lead to about 85% of the children lately infected in the course of pregnancy to present psychomotor retardation or corioretinită at birth distance until the age of 7 years.
There is often a reverse relationship between the risk of transmitting the infection and the severity of the disease. The frequency of maternal-foetal transmission varies according to the age of pregnancy as follows: It is around 25% if the infection occurs in the first trimester of pregnancy, about 54% if the infection occurs in the second trimester of pregnancy and about 65% if the infection takes place at Third trimester of pregnancy.
Acute infection in pregnant women is generally asymptomatic. The risk of infection for the fetus is not correlated with the absence or presence of symptoms in the mother, but with the time of infection. Women at risk are those that are infected during pregnancy, while those that were previously infected are generally protected from maternal-foetal transmission.
Clinical manifestations in pregnant
In more than 80% of cases the Primo-infection is asymptomatic. In about 20% of cases, when the infection is symptomatic the woman may present:
- Fever, generally moderate;
- Polyadenopathies (inflammation of the lymph nodes) in particular cervical and occipital, which may persist for several weeks to more than 85% of patients;
- Headache;
- Myalgia (muscle pain);
- Arthralgia (joint pain);
- Eruption, etc.
Clinical manifestations in the case of congenital toxoplasmosis (in the fetus or newborn)
Most clinical signs and manifestations are non-specific and may mimic diseases caused by other micro-organisms such as the herpes simplex virus, the Cytomegalovirus virus (CMV) and the Rubella virus.
Congenital toxoplasmosis is manifested by the triad: intracerebral calcification , chorioretinitis (ocular impairment) and hydrocephalus (accumulation of cerebrospinal fluid). Very few children present the full triad at birth. May also present other events such as epilepsy, psychomotor retardation, anaemia, jaundice, rash, thrombocytopenia, encephalitis, pneumonia, microcephaly, diarrhea, hypothermia.
Congenital toxoplasmosis can also occur under the appearance of a normality (at birth and a few years later) with the occurrence of symptoms either at school age or in young adolescents/adult in the form of a neuropsychiatric pathology (convulsions, spastic paralysis, Hyperkinetic syndrome with attention deficit, myoclonus, psychomotor retardation, autism) or ocular (progressive reduction of vision, blindness). This form occurs in about 65% of the infection cases in the third trimester of pregnancy and in those reactivated, regardless of gestational age.
Diagnosis
Women’s testing must be carried out before the woman is pregnant or at the latest from her first visit to the pregnant women’s gynecologist to know the status of specific anti-Toxoplasma gondii antibodies (T. gondii)
The most common diagnosis is made by the determination of anti-gondii IgM and IgG antibodies. Depending on the result obtained on a case-by-case basis, additional testing for elucidation may be carried out. The diagnosis is based on clinical signs and results of serological tests and can be completed (in reference centres) by isolating the parasite on cell cultures or demonstrating the presence of the parasite in the tissues or fluids of the body by biopsy or necropsy.
At fetus the diagnosis can be done by PCR testing (Polymerase Chain Reaction) from the amniotic fluid.
The confirmation of congenital infection is by detection of Ig M and Ig anti toxoplasma antibodies in the newborn.
Increased levels of IgG anti toxoplasma antibodies may persist for years without any relationship with acute disease.
At European level there are no regulations regarding the screening of pregnant women, but differ according to the prevalence of toxoplasmosis and public health policies at national level. The United States of America (USA) does not practice screening for toxoplasmosis, but in France and Austria it is governed by law to facilitate the early diagnosis of recent infections. In France, Austria, Belgium, Norway and Italy the screening is carried out in the first 3 months, followed by a retest program at 3 month, while in other countries there are no such programs. If screening tests are carried out, the recommendation shall be carried out as early as possible for the determination of the serological status and the avoidance of an ambiguous situation, as well as providing the information on preventive measures.
This site does not extensively treat the laboratory diagnosis of Toxoplasma gondii infection. Those interested may ask questions or consult additional specialist materials.
The infectious agent
Toxoplasmosis is caused by a parasite-Toxoplasma gondii (TG) that develops intracellularly and has as its final host the cat, the man intervening in the TG cycle as intermediate host.
Generally, the disease is asymptomatic and benign in the imunocompentent adult , but represents an important hazard for imunodeppressed patients and pregnant women.
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