Abstract
The seroprevalence of Toxoplasma gondii in Romanian children is currently unknown. A serological survey was undertaken to determine T. gondii infection among children from Western Romania. Serum samples of 441 children (aged 1–18 years) were screened for T. gondii immunoglobulin G and immunoglobulin M antibodies. The overall T. gondii seroprevalence was 16.6% and tended to increase with age. Seroprevalence was 18.4% in children from rural regions and 14.7% in those from urban regions. T. gondii antibodies were demonstrated in 19.5% of females and 13.3% of males. This report provided the first seroepidemiological data and evaluated the demographic risk factors regarding T. gondii infection in children from Western Romania. Our results may serve as a basis for a future prevention program for toxoplasmosis.
Toxoplasmosis, an important worldwide zoonosis, is caused by a single-celled obligate intracellular parasite called Toxoplasma gondii (Montoya and Liesenfeld 2004). Human infection can be acquired by ingestion of tissue cysts in raw/undercooked meat or oocysts excreted by cats that contaminate the environment (Cook et al. 2000). Oocysts shed by infected cats may be accidentally ingested by contaminated food (fruits or vegetables) or water, or by direct contact with cats (Torgerson and Mastroiacovo 2013).
T. gondii may cause severe disease in immunocompromised patients by reactivation of latent disease and congenital toxoplasmosis in infants following maternal transmission (Montoya and Liesenfeld 2004). Congenital infection with T. gondii can result in fetal death and abortion or severe fetal sequelae, that include neurological and neurocognitive deficits and chorioretinitis (Montoya and Liesenfeld 2004, Torgerson and Mastroiacovo 2013).
The prevalence of T. gondii infection among children varies between countries, from 4.1% in the United States (Jones et al. 2014) to 15.1% in China (Meng et al. 2015), and 64.1% in the Democratic Republic of Sao Tome and Principe, West Africa (Fan et al. 2012). In Europe, the prevalence of T. gondii infection among children varies from 8.8% in Netherlands (Hofhuis et al. 2011) to 20.5% in Slovakia (Strhársky et al. 2009). Information regarding T. gondii seroprevalence in children from Western Romania is currently unknown. We have recently shown a prevalence of 64.8% T. gondii antibodies in Romania's adult population (Olariu et al. 2015). Therefore, we decided to determine the seroprevalence of T. gondii in children from Western Romania.
We investigated serum samples of 441 consecutive children, referred between January 22, 2018 and March 9, 2018, for routine laboratory investigations, to “Louis Turcanu” Children's Hospital Outpatient Clinic in Timișoara, Romania. Children, aged 1–18 years (mean = 7.5 years), were residents of five counties (Arad, Caras-Severin, Hunedoara, Mehedinti, Timis) located in Western Romania, with a total population of 2,017,712. Children were grouped into three categories based on their school age: 1–5 years (preschool), 6–10 years (elementary school), and 11–18 years (middle/high school).
Serologic testing was performed at the Discipline of Parasitology of Victor Babes University of Medicine and Pharmacy, in Timișoara, Romania. Serum samples were tested for T. gondii antibodies using the PastorexToxo kit (Bio-Rad, Marnes-la-Coquette, France). This test simultaneously detects immunoglobulin G (IgG) and/or immunoglobulin M (IgM) antibodies to T. gondii, using latex particle agglutination.
Statistical analysis was performed using EpiInfo™ 7 (CDC, Atlanta, GA). Mantel-Haenszel chi-squared and Fisher's exact test two-tailed were used for comparison between the studied groups. A p value <0.05 was considered to indicate statistical significance. This study was approved by the Victor Babes University of Medicine and Pharmacy Timișoara Ethics Committee, and parents/guardians provided informed consent on behalf of all participants.
The overall seroprevalence of T. gondii infection was 16.6% (73/441) and tended to increase with age. The prevalence of T. gondii antibodies was significantly higher in children aged 11–18 years (26.8%; 34/127) compared with those aged 1–5 years (11.2%; 22/196) and 6–10 years (14.4%; 17/118) (p < 0.001 and p = 0.01, respectively).
The seroprevalence was 18.4% (40/217) in residents from rural regions compared with 14.7% in those from urban regions (33/224) (p = 0.29); the seroprevalence in females was 19.5% (45/231) compared to 13.3% in males (28/210) (p = 0.08) (Table 1).
Seroprevalence of Toxoplasma gondii Among Children in Western Romania According to Age, Area of Residence, and Gender
Overall p values.
Females aged 1–5 years and 6–10 years tended to be more infected with T. gondii (14.3% and 19.0%, respectively) compared with males from the same age groups (8.2% and 9.1%, respectively) (Table 1). No significant difference in seroprevalence was found between females residing in the rural area (19.8%; 22/111) and urban area (19.2%; 23/120 (p = 0.90). The seroprevalence among males residing in rural areas was 17.0% (18/106) compared to 9.6% in the males from urban regions (10/104) (p = 0.11).
Few information is available to the international scientific community regarding T. gondii seroprevalence in Romanian children (Dubey et al. 2014). Most studies on toxoplasmosis were published in Romanian in local journals and often not available to scientists in other countries (Dubey et al. 2014). The majority of those reports were published decades ago and assessed the prevalence of toxoplasmosis among hospitalized children or groups of children with disabilities or neuropsychiatric disorders in other Romanian regions (Radacovici and Atanasiu 1959, Georgescu 1976). In a survey based on stratified sampling from the general population in northwest and central Romania, Coroiu et al. (2009) reported a seroprevalence of 28.9% in 249 children, aged 1–19 years.
This study is the first report on the seroprevalence and demographic risk factors of T. gondii infection in children from Western Romania. Our results revealed that 16.6% of the children residing in Western Romania tested positive for T. gondii IgM and/or IgG antibodies. This seroprevalence is higher than the 8.8%, 9.3%, and 12.4% seroprevalence recently reported by European investigators in Netherlands (Hofhuis et al. 2011), Spain (Asencio et al. 2015), and Greece (Diza et al. 2005), similar with the 16.9% rate in France (Bellali et al. 2013) but lower than 20.5% rate reported among children in Slovakia (Strhársky et al. 2009), respectively. Of note, these seroprevalence rates were reported by European scientists using different serological methods for the diagnosis of toxoplasmosis.
As previously shown by former authors (Montoya and Liesenfeld 2004, Bellali et al. 2013), the presence of T. gondii antibodies increased with age in our study, and this trend was noted in both urban and rural areas, indicating past exposure. The slightly higher seroprevalence in children residing in rural areas (18.4%) compared with those residing in urban areas (14.7%), although not significant, might be explained by a potential higher exposure of children living in rural areas to environmental factors that contribute to such a seroprevalence, including contact with soil and/or pets. In Western Romania, the 70% seroprevalence for T. gondii in cats may contribute to the high seroprevalence in the rural population compared with those from urban areas (Olariu et al. 2015). Contact with cats' feces or soil that cats have defecated in has been found to be a risk factor for T. gondii infection, as the suspected source of outbreaks was the oocysts from soil (Montoya and Liesenfeld 2004).
We noted, in our study group, a trend toward a higher rate of T. gondii seropositivity in females compared to males, similar with the one reported in the adult population. We have earlier shown that Romanian adult females tend to be more often infected than adult males (Olariu et al. 2015).
In this study, we provided new valuable seroepidemiological data and evaluated the basic demographic risk factors for toxoplasmosis in Romanian children. Further studies should be conducted to evaluate the potential risk factors that may contribute to such seroprevalence among children and to determine the rate of congenital toxoplasmosis in Western Romania.
Footnotes
Author Disclosure Statement
No competing financial interests exist.