Toxoplasma gondii Prevalence in Pregnant Women in Jataí - GO: a 10-year profile

Prevalência do Toxoplasma gondii em Gestantes no Município de Jataí – GO: um recorte de 10 anos

Prevalencia de Toxoplasma gondii en mujeres embarazadas de la Ciudad de Jataí - GO: un período de 10 años

Esta obra está bajo una Licencia Creative Commons Atribución 4.0 Internacional.

Toxoplasmosis is an infection caused by the Toxoplasma gondii protozoan distributed worldwide and with high prevalence, especially in Brazil, where it has high genetic diversity^1,2. There are several forms of transmission of this disease, the main ones are the ingestion of oocyst-contaminated food and water and vertical transmission, when there is the passage of tachyzoites from the placenta to the fetus during the three trimesters of pregnancy^{3, 4}.

Given the high risk of T. gondii vertical transmission to the fetus associated with the severity of signs and symptoms of congenital toxoplasmosis, since 2015, the Ministry of Health has assigned the Health Surveillance Secretariat to monitor and supervise gestational and congenital toxoplasmosis in the country in order to standardize the care provided to pregnant women and their children after proven infection⁵. For this reason, the disease in these conditions was considered an important public health problem and its inclusion in the Compulsory Disease Notification List is an important strategy of this body to monitor the disease. From the investigation of risk cases or proof of gestational transmission, it is possible to identify the origin of the infection and the closure of outbreaks, and create prevention, control and treatment strategies for individuals affected by the disease^5-6.

Symptoms of congenital toxoplasmosis can manifest during fetal development, childhood and even puberty, or the disease can remain subclinical. After infection, the main signs presented by the fetus are chorioretinitis, microcephaly, macrocephaly, hydrocephalus, mental retardation, brain calcifications and even hearing loss^4,7. Gestational age and primary infection during pregnancy are the main factors responsible for T. gondii transmission to the fetus. The acute phase determines the pathogenicity of the parasite in the host, as well as the transmission rate and the severity of the baby’s involvement, especially if the mother’s infection occurs during the first gestational weeks, as it leads to abortion and several complications^8-9. Gestational age, in turn, determines the degree of transmission. The frequency of infection of the conceptus during the first trimester of pregnancy is 4.5%, in the second it is 17.3% and in the third trimester it is 75%^4,9-10. On the other hand, T. gondii vertical transmission is considered low in immunocompetent pregnant women who developed seroconversion to the parasite before pregnancy¹⁰.

The prevalence of seropositivity in pregnant women varies according to geographic region, cultural factors, climatic characteristics of the environment, educational level, self-reported color and age^{7,10, 11-13}. The worldwide prevalence of toxoplasmosis is 1.1%⁷, ranging from 10.9% in Norway¹⁴, 28.88% in Morocco¹⁵ and 30% in Germany¹⁶, with an average of 56.2% in South American countries⁷. In Brazil, it ranges between 32.7% in São Paulo and 92% in Mato Grosso do Sul¹⁰.

In the state of Goiás, data on the prevalence of toxoplasmosis is lacking. Given this reality, this cross-sectional study to determine the prevalence of toxoplasmosis in pregnant women in the city of Jataí became relevant. The lack of this information makes it impossible to recognize the situation of the disease in the place, and to create and adopt strategies to manage the disease in this group and the population.

In this descriptive cross-sectional study, the results of IgG and IgM serological tests for Toxoplasma gondii performed in pregnant women attended by the public health network in the municipality of Jataí, state of Goiás, between January 2005 and December 2015 were analyzed.

The test results were provided by the Institute for Diagnosis and Prevention (IDP) of the Association of Exceptional Parents and Friends (APAE), accredited by the state to perform all serological tests of pregnant women assisted by the National Health Service (Brazilian SUS).

The present study was approved by the Research Ethics Committee of the Universidade Federal de Goiás under number 1.882.407 and Certificate of Presentation of Ethical Appreciation 60106616.0.0000.5083.

During the selected period, 11,350 pregnant women were assisted. Of these, 8,514 (75%) had IgG anti-T. gondii antibodies (Table 1). The average annual number of cases was 774. A reduction and stabilization in the number of cases was observed after 2010. Pregnant women were significantly associated with seropisitivity of anti-T. gondii.

Table 1
Distribution of the number of services and pregnant women with positive IgG and IgM antibodies to T gondii served at the Rede Cegonha antenatal care service in the municipality of Jataí state of Goiás between 2005 and 2015

Among pregnant women assisted at the Rede Cegonha during the study period, 68 showed reactivity for IgM anti-T. gondii antibodies (Table 2).

In this study, 68 IgM-reactive pregnant women (0.60%) did this test and there was a predominance of cases with avidity >60% (79.41%), suggesting the occurrence of the infection more than 12 weeks before the test was performed, and the IgM found was considered as residual antibody. The opposite of 7.35% and 13.23% of mothers who presented results of avidity < 30% and between 30 - 60%, respectively, suggests maternal infection for less than 12 weeks, with a high possibility of transmitting the parasite to the fetus⁹.

The percentage of reactivity for T. gondii found in the city shows that most pregnant women attended had previous contact with the parasite before conception, reducing the chances of transmission of the disease to the fetus during pregnancy. The prevalence found was higher than that observed in Fortaleza, 68.6%¹⁷, Aracaju, 69%¹⁸, in Jaguapitã (city in the state of Paraná) 66%¹⁹, and in São Luiz (state of Maranhão) 66.38%²⁰. Seroprevalence in pregnant women remained high throughout the analyzed period, especially between 2005 and 2010, with a reduction and stabilization of infection in the number of cases after that year, demonstrating that this population is in close contact with factors that promote the infection, and the general population of the municipality may be in the same situation. Faced with this reality, the investigation of factors contributing to the high rate of infection in the population is essential, as well as the creation and implementation of primary measures for protection of the uninfected population, in addition to secondary and tertiary prevention measures for those who present symptoms and even sequelae of the disease.

The low prevalence of IgM observed (0.60%) was close to that found in studies conducted in Mato Grosso do Sul (0.42%)²¹ and Sergipe (0.40%)²², and lower than rates observed in a reference hospital in Rio de Janeiro (48.8%)²³. The period from 2008 to 2014 showed a significant increase in the number of cases, with greater evidence in the number of women who tested positive for the IgM anti-T. gondii antibody. This situation may indicate an outbreak of toxoplasmosis in the municipality, despite the lack of information to prove such suspicion, since clinical signs of acute toxoplasmosis can be easily confused with other infections and are mostly self-resolving²⁴. For this reason, the diagnosis for the disease is often unconfirmed or confused with other infections.

For women who have not had previous contact with T. gondii, (24.99%) it is recommended to increase care to avoid contamination by the protozoan, considering the severity of signs and symptoms that fetuses and neonates present when infected in utero.

It is possible to conclude that the municipality of Jataí has a high number of pregnant women who had previous contact with T. gondii. The high prevalence of anti-T. gondii antibodies in pregnant women points to an important public health problem, because in certain situations, such as the fall of immunological mechanisms of affected individuals, toxoplasmosis can generate serious physiological changes²⁵.

Knowing the real situation of the disease in the population of the municipality as well as the factors responsible for maintaining the cases is of paramount importance, since even asymptomatic in most cases, toxoplasmosis is an opportunistic infection with serious sequelae when carriers have some type of immunosuppression. Therefore, its monitoring is essential for effective health surveillance actions.

In particular, we thank the administrative director of the Institute for Diagnosis and Prevention of the Association of Exceptional Parents and Friends of Goiânia, Goiás, José Vicente Macedo Filho for providing data and Mayara Bocchi Fernandes for performing the statistical analysis.