ABSTRACT
Toxoplasma gondii (T. gondii) is a protozoan parasite that infects most warm-blooded animal species and causes toxoplasmosis. Especially infections that occur during pregnancy can lead to serious clinical symptoms. This study retrospectively revealed the T. gondii seroprevalence of pregnant women in Kastamonu province, Turkey.
Anti-T. gondii IgM and IgG positivity of 1.294 pregnant women between the ages of 15-44 years who applied to the Obstetrics and Gynecology Outpatients of Kastamonu Training and Research Hospital from January 2018 to January 2022 were investigated retrospectively. The IgG avidity test was performed for both anti-T. gondii IgM and IgG positivity.
Anti-T. gondii IgM and IgG seropositivity were determined as 1.1% (n=14) and 20.3% (n=263), respectively. Anti-T. gondii IgM and IgG positivity were detected together in 11 pregnant women. IgG avidity test results of only six pregnant women could be reached, two pregnant had high IgG avidity, and four pregnant had low IgG avidity. Anti-T. gondii IgG positivity rate increased with increasing age (p=0.039).
The number of seronegative pregnant women was considered high in Kastamonu. It is significant for expectant mothers to know about prevention methods in order not to acquire toxoplasmosis.
Keywords: Pregnancy, IgG, IgM, seroprevalence, Toxoplasma gondii
INTRODUCTION
Toxoplasma gondii (T. gondii) is a protozoan parasite that infects most warm-blooded animal species and causes toxoplasmosis. Felines act as definitive hosts and other animals as intermediate hosts in the life-cycle of the parasite. Humans are accidental intermediate hosts (1,2).
Humans become infected by consuming the oocysts of the parasite (not washing hands after contact with contaminated cat litter or soil, consuming contaminated fruits and vegetables without washing) or the undercooked meat of intermediate hosts (poultry, cattle, sheep, goat, etc.) that have bradyzoite. In addition, T. gondii can be transmitted from person to person by contaminated blood or tissue transplantation, as well as transplacental from mother to fetus (1,2).
Toxoplasmosis is usually asymptomatic in immunocompetent individuals (3). However, it can cause serious clinical symptoms in immunocompromised individuals and congenital toxoplasmosis (4). Congenital toxoplasmosis occurs when the mother is infected during pregnancy. The incidence and severity of congenital toxoplasmosis vary based on the period of pregnancy. Especially infections occurring in the first trimester of pregnancy may result in abortion. On the other hand, newborns are usually asymptomatic in infections occurring in the later stages of pregnancy. However, pathologies such as hydrocephalus, intracranial calcifications, chorioretinitis, hepatitis, pneumonia, myocarditis, and mental retardation may occur in the future (5).
Rapid and accurate diagnosis of toxoplasmosis in pregnant can reduce the incidence of congenital toxoplasmosis. Detection of antibodies specific to T. gondii in the serum samples is the primary diagnostic method used to detect toxoplasmosis (6). For example, IgM positivity alone or seroconversion in IgG titers suggests acute toxoplasmosis. Since IgG can persist for years, detecting IgG positivity alone suggests a past infection. On the other hand, since IgM positivity can persist in serum for up to one year after acute infection, the IgG avidity test should be performed when IgG and IgM are positive together. High IgG avidity indicates that the agent was encountered at least 3-4 months ago, while low IgG avidity may mean acute toxoplasmosis, and the result should be confirmed in a reference laboratory (2).
Knowing the T. gondii seroprevalence of pregnant women in a province can provide information about the risk of acquiring toxoplasmosis in pregnant candidates in that province (7). There is no data in the literature about T. gondii seroprevalence of pregnant women in Kastamonu province, Turkey. This study aimed to investigate the T. gondii seroprevalence of pregnant women who applied to the Obstetrics and Gynecology Outpatients of Kastamonu Training and Research Hospital (TRH).
METHODS
Study Population
The population of the study consisted of pregnant women between the ages of 15 and 44 years who applied to Kastamonu TRH the Obstetrics and Gynecology Outpatients for routine pregnancy control between January 1, 2018, and January 1, 2022. T. gondii-specific IgG and IgM-type antibody values of these patients were analyzed retrospectively. The first serological results belonging to the same person were evaluated.
Serological Test
Anti-T. gondii IgM, anti-T. gondii IgG and IgG avidity were determined by the chemiluminescent microparticle immunoassay method. The tests were performed using Abbott Architect i2000SR instrument (Chicago, IL, USA) per the manufacturer's instructions. The following values were considered to be negative, gray zone, and positive, respectively, in the tests: for IgM, <0.5 index, ≥0.5 - <0.6 index, and ≥0.6 index; for IgG <1.6 IU/mL, 1.6 - <3.0 IU/mL, and ≥3.0 IU/mL; for IgG avidity <50%, ≥50% - <59.9%, and ≥60%.
Statistical Analysis
The pregnant women were divided into three age groups: 15-24, 25-34, and 35-44. The distribution of seropositivity by age groups was evaluated using the Pearson chi-square test in SPSS 23.0 for Windows (IBM Inc., Armonk, NY, USA). The statistical significance was admitted as p<0.05.
RESULTS
A total of 1294 pregnant women aged between 15-44 years were included in this study. The mean age of the patients was 27.6±5.5. The distribution of pregnant women by age group was as follows: 407 pregnants (31.5%) in the 15-24 age group; 732 pregnants (56.5%) in the 25-34 age group; 155 (12%) pregnants in the 35-44 age group. Anti-T. gondii IgM and anti-T. gondii IgG were positive in 14 (1.1%) and 263 (20.3%) pregnant women, respectively. Anti-T. gondii IgM and anti-T. gondii IgG positivities were detected together in 11 pregnant women (Table 1). IgG avidity test results of only six pregnant women could be reached, two pregnants had high IgG avidity and four pregnants had low IgG avidity. The anti-T. gondii IgG positive rate increased with age groups (p=0.039). The highest rate of anti-T. gondii IgG positivity (27.7%) was in the 35-44 age group (Table 2).
DISCUSSION
Toxoplasmosis is a parasitic zoonosis that threatens public health. In particular seronegative pregnant women are at risk due to T. gondii being a teratogenic pathogen. Serological tests are used in the diagnosis and follow-up of toxoplasmosis (8,9). Anti-T. gondii IgG is permanent for life and provides acquired immunity (2). If the anti-T. gondii IgG seronegativity is high in pregnant women in a region or a province, future cases of congenital toxoplasmosis may be inevitable unless necessary protective measures (giving importance to hand hygiene after contact with raw meat, soil, pets, and stray cats, consuming well-cooked meats and sanitizing vegetables and fruits, etc.) are handled (10). In particular, pet ownership or stray cat feeding can pose a risk for pregnant women. For instance, Karakavuk et al. (11) stated that more than 14.0% of stray cats were infected with T. gondii and they would be acted as reservoirs for humans and other warm-blooded animals in İzmir province, Turkey.
Anti-T. gondii IgG seropositivity in pregnant women has been reported to be about 32.9% worldwide. The highest seropositivity (45.2%) was reported from the Americas and the lowest seropositivity (11.2%) was from the western pacific region (12). T. gondii seroprevalence studies among pregnant women in the last ten years conducted in Turkey are summarized in Table 3. Briefly, anti-T. gondii IgG seropositivity has been reported in the range of 14.5-47.1% in Turkey (13-36). Anti-T. gondii IgG seropositivity was found at 20.3% in the presented study. The findings showed that anti-T. gondii IgG seropositivity seropositivity rate was lower than most studies reported in Turkey. The low rate of seropositivity in Kastamonu might be attributed to socio-cultural and socio-economic distinctions such as dietary habits as well as geographical location (37). Moreover, the anti-T. gondii IgG seropositivity was determined to increase with age in the current study, which was consistent with the literature (15,18,23,30,33,34). This result can be attributed to the fact that individuals are more in contact with the outdoors with increasing age, thus increasing the possibility of consuming contaminated food or being exposed to infective oocysts.
Anti-T. gondii IgM is used in the diagnosis of acute toxoplasmosis (2). Anti-T. gondii IgM seropositivity in pregnant women has been reported to be about 1.9% worldwide. The highest seropositivity (4.1%) was reported from the Eastern Mediterranean region and the lowest seropositivity (1.1%) was from the Americas (12). The anti-T. gondii IgM seropositivity has been reported in the range of 0.0-3.7% in studies conducted in Turkey in the last ten years (13-36). The anti-T. gondii IgM positivity was detected at a rate of 1.1% in this study. The results showed that the anti-T. gondii IgM seropositivity rate was similar to most studies reported in Turkey. However, anti-T. gondii IgM test may give false results in favor of acute toxoplasmosis due to its low specificity. For this, the patient’s serum sample should be redrawn two weeks after the first, and it should be investigated whether there is an increase in anti-T. gondii IgG titers. If there is indeed an acute infection, anti-T. gondii IgG will begin to be detected two weeks after the first test (2). Only three patients had anti-T. gondii IgM positivity alone in the current study. Unfortunately, there is no information about the fate of these patients does not exist in Kastamonu TRH.
On the other hand, anti-T. gondii IgM can persist in serum for a long time (up to 1 year) after acute toxoplasmosis. Therefore anti-T. gondii IgM and anti-T. gondii IgG positivities can be detected at the same time. Then, the IgG avidity test should be done to determine the time of infection. Detection of high IgG avidity in the first trimester of pregnancy can exclude that the toxoplasmosis occurred during pregnancy. However, the detection of low avidity may consider a recent toxoplasmosis, and specimens should be sent to a reference laboratory for further testing (2). Anti-T. gondii IgM and anti-T. gondii IgG were positive together in 11 pregnant women in this study. However, the IgG avidity test results of six pregnant women were reached. Of these, four pregnant women had low IgG avidity, and two pregnant women had high IgG avidity.
CONCLUSION
Kastamonu TRH is the central hospital of the province. Therefore, the data of this study reflect the Kastamonu province. Based on the results, the number of seronegative pregnant women was considered high in Kastamonu. Therefore, expectant mothers need to know the prevention methods for toxoplasmosis. Also, routine examination of T. gondii serology of all women of childbearing age is recommended.
*Ethics
Ethics Committee Approval: The study was permitted by the Kastamonu University Faculty of Medicine Non-Interventional Clinical Research Ethics Committee (date: 09.03.2022 and decision number: 2022-KAEK-17).
Informed Consent: Retrospective study.
Peer-review: Internally peer-reviewed.
Authorship Contributions
Surgical and Medical Practices: A.U., Concept: M.Y.D., Ç.K., Design: Ç.K., Data Collection or Processing: M.Y.D., B.Ç., Ç.K., A.U., Analysis or Interpretation: E.F.T., M.Y.D., B.Ç., Literature Search: E.F.T., B.Ç., Writing: E.F.T.
Conflict of Interest: No conflict of interest was declared by the authors.
Financial Disclosure: The authors declared that this study received no financial support.
