Seroprevalence Of Toxoplasma Gondii Antibodies And Associated Risk Factors Among Children In Lorestan Provinces, Iran

Abstract

Children due to their high hand-mouth activity, lack of hygiene standards in the consumption of food, water, fruits and vegetables and their immature immune systems are the most susceptible peoples to parasitic infections among all age groups. This cross-sectional study aims to determine the prevalence of IgM and IgG anti- Toxoplasma gondii antibodies and the associated risk factors among the Children (5–15 yr Old) Referred to health centres of Lorestan province, Iran from August 2016 to March 2017 on 316 children. To determine the anti- T. gondii antibodies, all the serum samples were tested using the commercially available ELISA kit (Dia.Pro, Milano, Italy). Analyses were carried out according to the manufacturer’s instructions. Out of the 316 children, 31 (9.8%) tested seropositive for anti- T. gondii antibodies; 24 (7.6%) children tested seropositive for IgG antibody, 1 (0.3%) tested seropositive for both IgM and IgG, and 6 (1.9%) were positive for IgM antibody alone. The results showed that some risk factors were significantly correlated to T. gondii seropositivity included age (P= 0.005), living in rural areas (P=0.01) and consumption of undercooked or cured meat products (P<0.001). The findings of our study demonstrated a considerable seroprevalence of T. gondii infection in children in Lorestan province, Iran. Thus, proper strategies must be carried out to prevent and control T. gondii infection in children in this region.

Keywords: ToxoplasmosisIgGIgMchildrenIran

Introduction

Toxoplasma gondii as a well-known protozoan parasite which uses domestic cats as its final host is

prevalent among animals and humans around the world (Hill & Dubey, 2002). Naturally, Humans acquire

toxoplasmosis chiefly during direct contact with the soil or fortuitously consumption of water or food

contaminated with oocysts passed in cat feces (Hill & Dubey, 2002; Furtado, 2011). The disease in the

immunocompetent adults and children are generally without symptoms or cover gentle and impulsively

resolved signs; for example, fever, fatigue, lethargy and lymphadenopathy (Furtado, 2011;

Mahmoudvand, 2016). On the other hand, toxoplasmosis in immunocompromised patients such as

transplant recipients and patients with acquired immunodeficiency syndrome and the fetus can give rise to

serious and fatal symptoms such as eye infection and brain involvements (Signorini et al., 2007;

Torgerson & Mastroiacovo, 2013). The diagnosis of T.gondii infection is usually based on serological

tests to find the anti- T. gondii antibodies; so that IgM and IgG anti- T. gondii antibodies are typically well-

known as a indicator of acute and chronic infection respectively (Hill & Dubey, 2002).

Problem Statement

Reviews have shown that depending on social and cultural behaviour, geographic locations,

weather, and the routes of transmission frequency of toxoplasmosis varies broadly between different

countries from 10 to 80% worldwide (6). In Iran, studies demonstrated that generally seroprevalence rate

of T. gondii infection among the general population was nearly 39.3% (95% CI = 33.0%–45.7%)

(Daryani et al., 2014).

Children due to their high hand-mouth activity, lack of hygiene standards in the consumption of

food, water, fruits and vegetables and their immature immune systems are the most susceptible peoples to

parasitic infections among all age groups (Weatherhead & Hotez, 2015). So far, in numerous

investigations the seroprevalence of T. gondii infection in children has been demonstrated in several

countries around the world (Fu et al., 2014; Xin et al., 2015), however little is known about the

seroprevalence of T. gondii infection in children in Iran.

Research Questions

Based on the concerns mentioned, we have two research questions:

1) What is the seroprevalence rate of toxoplasmosis among children referred to health centres in the

Lorestan province, Iran using the ELISA method?

2) What is the seroprevalence rate of toxoplasmosis among children referred to the health centres of

Lorestan province, Iran in terms of risk factors such as age, sex, place of residence, etc.?

Purpose of the Study

This cross-sectional study aims to determine the prevalence of IgM and IgG anti- T. gondii

antibodies and the associated risk factors among children aged 5–15 years old referred to health centres

of Lorestan province, Iran.

Research Methods

Findings

Conclusion

Toxoplasmosis has been explained as the most prevalent zoonotic infection of humans as well as

animals (Sukthana, 2006).The disease in immunocompetent adults and children is generally without any

symptoms or cover gentle and spontaneously treated signs for instance, fever, discomfort, and

lymphadenopathy. But toxoplasmosis in immunocompromised individuals and the fetus can cause serious

and fatal symptoms (Signorini et al., 2007; Torgerson & Mastroiacovo, 2013). Nowadays, the diagnosis

of human toxoplasmosis is usually based on the detection of the anti T. - gondii antibodies by serological

methods including ELISA, latex agglutination (LA), and indirect fluorescent antibody (IFAT) (Robert-

Gangneux & Darde, 2012). In serological tests, anti- T. gondii IgM antibodies are typically recognized as

an indicator of acute toxoplasmosis that show earlier and reduce sooner than IgG antibodies. However, T.

gondii specific IgM may occasionally continue for more than one year post-infection, which indicated the

false positive diagnoses of acute toxoplasmosis whereas no supplementary examinations for anti- T.

gondii -IgG antibodies were performed (Lim & Othman, 2014; Balfour et al., 1982). As a result, the

diagnosis of newly acquired toxoplasmosis is commonly based on the recognition of specific IgM

antibodies, followed by detecting the anti- T. gondii -IgG 1 to 3 weeks later (Lim & Othman, 2014;

Balfour et al., 1982).

Children due to their high hand-mouth activity, lack of hygiene standards in the consumption of

food, water, fruits and vegetables and their immature immune systems are the most susceptible peoples to

parasitic infections among all age groups (Weatherhead & Hotez, 2015). So far, in numerous

investigations the seroprevalence of T. gondii infection in children has been demonstrated in several

countries around the world (Fu et al., 2014; Xin et al., 2015), however little is known about the

seroprevalence of T. gondii infection in children from Iran. In the present investigation, totally 316

children (aged 2-15 years), referring to health centres of Lorestan province, Iran were studied to

determine the anti- T. gondii antibodies. The obtained results showed that 31 (9.8%) children tested

seropositive for anti- T. gondii antibodies; 24 (7.6%) children tested seropositive for IgG antibody, 1

(0.3%) tested seropositive for both IgM and IgG, and 6 (1.9%) were positive for IgM antibody alone. This

seroprevalence of toxoplasmosis was higher than the values reported among children of southern Brazil

(7.4%), Swaziland (8%); while it was significantly lower than São Tome and Principe (63.1%),

Madagascar (36.3%), and China (15.13%) (Fan, 2012; Xin et al., 2015; Lopes, 2008; Dromigny, 1996).

This difference is most probably because of variations in sample size, experiments method, nutritional

habit and climatic conditions.

In line with studies conucted by Ali et al (2007) and Gyang et al (2015), we found that the

seroprevalence of anti- T. gondii antibodies among children referring to health centres of Lorestan

province, Iran increased with age; which is most likely due to increased opportunity for exposure.

Furthermore, in this survey, consistent with the some previous studies, we reported that some risk factors

such as consumption of raw or unwashed vegetables and fruits and consumption of undercooked or cured

meat products are related to T. gondii seropositivity; indicating that among children in the present study,

both infection ways, the ingestion of oocysts and consumption of tissue cyst in meat were present

(Montoya & Liesenfeld, 2004; Alvarado-Esquivel, Estrada-Martínez, Liesenfeld, 2011).

The findings of our study demonstrated a considerable seroprevalence of T. gondii infection in

children in Lorestan province, Iran. Thus, proper strategies must be carried out to prevent and control T .

gondii infection in children in this region.

Acknowledgments

We thank the staff of the health centres of Lorestan province, Iran for their assistance to collect the blood samples.

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