10-Jafari

JRHS 2012; 12(2): 119-121

Copyright © Journal of Research in Health Sciences

Seroprevalence of Toxoplasma gondii Infection and Related Risk Factors in Tabriz City, Iran, 2008

Rasool Jafari (MSc)a*, Mohammad Sadaghian (PhD)b, Marzieh Safari (MSc)c

a Department of Medical Parasitology, School of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran

b Department of Pathobiology, School of Veterinary Medicine, Shabestar Branch, Islamic Azad University, Shabestar, Iran

c Department of Medical Microbiology, School of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran

* Correspondence:Rasool Jafari (MSc), E-mail: rasooljafariii@gmail.com

Received: 02 August 2012, Revised: 03 September 2012, Accepted: 18 September 2012, Available online: 26 September 2012

Abstract

Background: Toxoplasma gondii is a worldwide obligate intercellular parasite. Felids are its definitive host and warm-blooded animals including humans are its intermediate host. The aim of this seroepidemiological study was to investigate the frequency of human infection using ELISA method and related risk factors in Tabriz City, northwestern Iran.

Methods: In this cross sectional study, 171 blood samples were collected randomly from clients referred to Alinasab Hospital diagnostic laboratory, Tabriz, Iran in 2008. Simultaneously data about risk factors such as having soil related jobs (for example: building construction workers and farmers), cat contact, eating raw vegetables at restaurants, the method of washing vegetables, eating undercooked game meat and the quantity of red meat consumption (undercooked) were collected by questionnaires. Anti-Toxoplasma IgG titers were determined in samples using ELISA method. Data were analyzed by Chi-square, One Way ANOVA and t-test using SPSS v.16 Software.

Results: Sixty (35.1%) out of 171 serum samples were anti-Toxoplasma IgG positive. There was statistically significant difference about seropositivity between soil related jobs and others (P=0.007, OR=2.43; 95% CI: 1.27, 4.66). In addition there was significant relationship between seropositivity and eating vegetables at restaurants (P=0.039, OR=1.94; 95% CI: 1.02, 1.68). No significant statistical differences were observed about seropositivity considering the other mentioned risk factors.

Conclusion: The prevalence rate of Toxoplasma chronic infection was relatively high in the studied people. However, having soil related jobs and eating vegetables at restaurants increases the probability of acquiring the infection.

Keywords:Toxoplasma gondii, Risk factors, Human, ELISA, Iran

Introduction

Toxoplasma gondii  is a cosmopolitan obligate intercellular protozoan parasite belonging to the phylum Apicomplexa which causes the most frequent parasitic infection of animals and human being. During infection of felids as definitive hosts, millions of oval shaped oocysts (10×12 µm in size) spread out in the faeces for up to 3 weeks1. After a short sporulation period, oocysts become infective then the intermediate hosts which consisting of even felids, can be infected by ingesting of food and water contaminated with infective oocysts. In addition, ingesting raw or undercooked meat can be infective when containing tissue cyst 2, 3. Human infection is usually asymptomatic in cases that have normal immune system, but it makes serious disease in immunocompromised/suppressed hosts. For example, it can cause severe toxoplasmic encephalitis in patients of immunodeficiency such as HIV positive individuals 3,4. In order to control the infection and its consequences, it is necessary to have updated information about prevalence rate and responsible risk factors in each geographical region.

In Iran like other countries, epidemiological studies have been done and reported different prevalence in different regions throughout the country, as in northern Iran 55.7% 5, in Ilam Province 44.8% in pregnant women6, in Isfahan Province 41.4% 7 and 63.9% in Babol 8.

We conducted a cross-sectional study to determine the prevalence of anti-Toxoplasma IgG using ELISA method, on subjects referred to one of the main laboratories in Tabriz, northwest Iran.

Methods

In a cross sectional study, 171 blood samples were collected from clients referred to a main diagnostic laboratory during March 2008 in Tabriz City, northwestern Iran. All cases were in range of 18 to 40 year old. Data were collected about their sex, cat contact, the method of washing vegetables, eating undercooked red meat, consuming vegetables at restaurants and having soil related jobs such as: building construction workers and farmers. The separated sera were kept in -20 °C until examination. After ending the sampling, sera were thawed at room temperature and anti-Toxoplasma IgG concentrations in the sera were determined using ELISA kits (Euroimmun®, Germany).

Titers higher than 11 IU/ml regarded as positive, 9-11 IU/ml borderline and lower than 9 IU/ml considered negative. ELISA kites applied in ELISA microplate washer (Anthos fluido®, Austria) for washing the microplate with 450 µl washing buffer per well 3 times and ELISA microplate reader (anthos® 2020, Austria) for photometric measurement at a wavelength of 450 nm following the instruction of manufacturer.

Data were analyzed by Chi-square, One Way ANOVA and t-test using SPSS v.16 Software.

Results

Sixty (35.1%) out of 171 serum samples were anti-Toxoplasma IgG positive. Among studied risk factors, there was statistical significant difference about seropositivity between soil related jobs (P=0.007, OR=2.43; 95% CI: 1.27, 4.66). Moreover there was significant relationship between seropositivity and eating vegetables at restaurants (P=0.039, OR=1.94; 95% CI: 1.02, 1.68). Although, seropositivity was quantitatively higher in subjects who washed their consuming vegetables without using detergent/disinfectants comparing to subjects who did so (P=0.090, OR=1.74; 95% CI: 0.91, 3.33), but the difference was not significant (Table 1). No significant statistical differences were observed about seropositivity considering the cat contact and the quantity of undercooked red meat consumption.

Despite the anti-Toxoplasma IgG concentration mean was higher in males comparing to females as well as subjects who had not have constant cat contact, having soil related jobs, having the habit of eating vegetables at restaurants, consumption of large amount of undercooked red meat (e.g. kabob) in comparison with others, the differences were not significant statistically (Table 2).

Table 1: The association between Toxoplasma seropositivity and potential risk factors in Tabriz City, 2008

Table 2: Distribution of anti-Toxoplasma IgG mean by potential risk factors using t-test

Discussion

From total of 171 studied sera, sixty (35.1%) were anti-Toxoplasma IgG seropositive that indicates fairly high prevalence. In Iran variety of epidemiological studies have been carried out in different regions, for instance, Jahani et al. performed a similar study in Qazvin Province on unmarried women and found 34% seropositivity9. Ghorbani et al. reported 23.2% prevalence rate of toxoplasmosis in neighboring cities which is lower than what we found10, also in 1987 reported that 55.7% of people living in rural area of northern Iran were Toxoplasma seropositive 5. Highest prevalence as 55.7% and 87% has been reported from Caspian Sea basin, northern parts of Iran11, 12. Assmar et al found that 51.8% of general populations of Iran were infected which is higher than ours 13. Fallah et al. in 2008 reported 33.5% seroprevalance of toxoplasmosis among primigravida women in Hamadan City also undercooked meat consumers (barbecue) and daily raw vegetables consumers had the highest prevalence12.

In our study despite the higher frequency of anti-Toxoplasma IgG in humans that consume large amount of undercooked red meat (P=0.12, OR=2.12; 95%CI: 0.8-5.59), wash their everyday used vegetables just by water (P=0.09, OR=1.74; 95%CI: 0.91-3.33), but were not significant statistically. According to our results, having soil related jobs and eating vegetables at restaurants can significantly increase the probability of infection (Table 1). Our findings showed significant higher prevalence in cases that had soil related jobs than others which might be caused by more exposure to different infected agents during the work.

Given to traditional customs among Iranian people, keeping the cat at home is mostly denounced, but unfortunately there are large populations of stray cats that shed large amount of their feces around dwellings and farms which considerably increases the possibility of cultured vegetables contamination to Toxoplasma oocysts. Our findings revealed a lower frequency of infection of humans in contact with cat comparing to others, which does not support those of Fallah et al. (2005) and Youssefi et al. (2007) that reported significant relationship between infection and cat contact8, 14, but the quality of contact and hygienic status of the cats can be important factor. Among the studied cases, 63.8% were washing their vegetables only by water. In our study numerically, the highest rate of IgG seropositivity was recorded in the group that used to wash their vegetables only by water whereas the lowest was in a group that used disinfectants/detergents, but the difference was not significant statistically. In addition no significant relationship between gender and prevalence rate of toxoplasmosis was observed, which is supporting those Assmar et al, reported in 1997 13.

Conclusion

The prevalence of toxoplasmosis was 35.1% that indicates fairly high prevalence in the residents of Tabriz, but comparing to results of studies in neighboring regions 5, 11, 12 in the country, it can be concluded that the prevalence is moderate comparing to other regions of country. Moreover based on our results, cat contact, daily washing of consuming vegetables just by water, eating large amount of undercooked red meat and eating undercooked game meat have no significant effect on the rate of seropositivity, whereas having soil related jobs and eating vegetables at restaurants increases the risk of infection.

Acknowledgements

We thank all that helped us in this study especially the personnel of Alinasab Hospital Diagnostic Laboratory and Dept. of Pathobiology of Islamic Azad University of Shabestar for their effort, help and contributions.

Conflict of interest statement

No conflict of interest was to be mentioned.

Funding

No financial support was provided. 

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