SEROPREVALENCE AND RISK FACTORS ASSOCIATED WITH Toxoplasma gondii INFECTION AMONG RURAL COMMUNITIES IN NORTHERN IRAN

Modeling the human placental barrier to understand Toxoplasma gondii´s vertical transmission

Toxoplasma gondii is a ubiquitous apicomplexan parasite that can infect virtually any warm-blooded animal. Acquired infection during pregnancy and the placental breach, is at the core of the most devastating consequences of toxoplasmosis. T. gondii can severely impact the pregnancy’s outcome causing miscarriages, stillbirths, premature births, babies with hydrocephalus, microcephaly or intellectual disability, and other later onset neurological, ophthalmological or auditory diseases. To tackle T. gondii’s vertical transmission, it is important to understand the mechanisms underlying host-parasite interactions at the maternal-fetal interface. Nonetheless, the complexity of the human placenta and the ethical concerns associated with its study, have narrowed the modeling of parasite vertical transmission to animal models, encompassing several unavoidable experimental limitations. Some of these difficulties have been overcome by the development of different human cell lines and a variety of primary cultures obtained from human placentas. These cellular models, though extremely valuable, have limited ability to recreate what happens in vivo. During the last decades, the development of new biomaterials and the increase in stem cell knowledge have led to the generation of more physiologically relevant in vitro models. These cell cultures incorporate new dimensions and cellular diversity, emerging as promising tools for unraveling the poorly understood T. gondii´s infection mechanisms during pregnancy. Herein, we review the state of the art of 2D and 3D cultures to approach the biology of T. gondii pertaining to vertical transmission, highlighting the challenges and experimental opportunities of these up-and-coming experimental platforms.

Prevalence of Toxoplasma gondii Antibodies in Individuals Occupationally Exposed to Livestock in Portugal

Toxoplasmosis is a worldwide zoonotic disease with different and complex routes for transmission. Workers occupationally exposed to animals or raw meat and viscera (WOE) may be at more risk than the general population, however conflicting data exist on the risk of developing toxoplasmosis due to this close contact. To add knowledge to this topic, the aim of the present study was to ascertain if WOE were more likely to be anti-T. gondii IgG seropositive than the general population as well as to study risk factors for T. gondii infection such as professional activity, gender, age, years of work and region. For this purpose, a case−control study using archived samples was setup. A total of 114 WOE (including pig slaughterhouse workers, butchers, veterinarians and farmers) and 228 anonymous volunteers (matched with cases by region, age and gender) were studied for anti-T. gondii IgG. A significantly higher anti-T. gondii IgG occurrence (p = 0.0282) was found in WOE when compared with the general population (72.8% [CI = 64.6−81.0%] versus 60.1% [CI = 54.6−65.6%]). Multivariate analysis showed that WOE of more than 50 years of age were more likely to be seropositive for anti-T. gondii IgG (aOR = 16.8; 95% CI 3.6−77.5; p < 0.001) than those aged less than 50 years. To our knowledge, this is the first case−control study on the prevalence of anti-T. gondii IgG in WOE in Portugal, also showing an added risk for T. gondii infection in those exposed to animals or their meat and viscera.

Seroprevalence and Risk Factors Associated with Toxoplasma gondii Infection in the Population Referred to Rural and Urban Health Care Centers in Zahedan, Primary Referral Level, in Southeastern Iran

Introduction. Toxoplasmosis is one of the protozoan diseases caused by Toxoplasma gondii. This study is aimed at evaluating the seroprevalence and associated risk factors of Toxoplasma gondii infection in the population referred to rural and urban health care centers in Zahedan, southeast Iran. Methods. A total of 1,324 blood samples of patients referred to the health care centers were evaluated using the IgG Toxoplasma ELISA Kit, between October 2019 and August 2021. The obtained data were analyzed through univariable and multivariable regression models. Results. The seropositivity of Toxoplasma gondii infection was obtained at 18.8%. In the multivariable logistic regression model, risk factors including age group of 11-30 ( $\text{OR}=3.25$ , 95% CI: 1.29-7.06), urban residency ( $\text{OR}=4.36$ , 95% CI: 2.9-6.3), students ( $\text{OR}=3.76$ , 95% CI: 1.88-4.53), and contact with cat ( $\text{OR}=7.67$ , 95% CI: 4.76-12.36) were significantly associated with seropositivity to Toxoplasma gondii infection. Moreover, consumption of washed vegetables with salt or detergents decreases ( $\text{OR}=0.14$ , 95% CI: 0.09-0.23) the risk of Toxoplasma gondii infection. According to the results of the multivariable logistic regression, no significant association was observed between seropositivity to Toxoplasma gondii and other risk factors. Conclusion. The results of this study indicated significant seropositivity to Toxoplasma gondii infection in the population referred to rural and urban health care centers in Zahedan, Iran. Therefore, health programs should be considered for raising awareness regarding the risk factors for Toxoplasma gondii infection in this region.

A serological survey of Toxoplasma gondii in polish pigs from organic farms, other housing systems and in pigs of different age groups

Background

The consumption of raw or undercooked meat, especially pork, and offal containing infective tissue cysts is suspected to be a significant route of infection with Toxoplasma gondii. Although the use of “animal-friendly pig production systems” ensuring direct contact with the natural environment offers ethical benefits, it limits the ability to ensure animal health; it may also increase the probability of infections by pathogens such as T. gondii, and thus their entry into the food chain. This study determines the seroprevalence of T. gondii in pigs from different housing systems and farms with different hygiene standards in Poland, as well as among pigs of different age groups from farms with high hygiene standards. In total 760 pig serum samples were examined for the presence of specific antibodies using the PrioCHECK^® Toxoplasma Ab porcine commercial ELISA test (Prionics, Switzerland).

Results

Test results with PP ≥ 20% were regarded as positive, as indicated by the manufacturer. Antibodies to T. gondii were found in 193 of 760 (25.4%) tested sera. Regarding different housing systems, antibodies were found in 117 pigs: of these, 52.6% (61/116) were from organic farms, 40.9% (47/115) from farms with low hygiene standards, 5.4% (9/167) from farms with high hygiene standards and 0% (0/40) from a farm with a high level of biosecurity. Regarding age groups, antibodies were found in 76 animals on farms with high hygiene standards: 11.1% (7/63) were pigs younger than 3 months, 0% (0/60) aged 3–4 months, 12.3% (7/57) aged 5–6 months (final fattening stage) and 43.7% (62/142) were sows aged 9 months and older.

Conclusions

Antibodies to T. gondii were most often found in pigs from organic and low-hygiene farms, as well as in pigs aged 9 months and older. Meat derived from seropositive animals can pose a potential source of infection for humans. As maternal antibodies to T. gondii can be present in the blood of piglets aged up to 3–4 months, serological examination is unjustified in piglets up to this age.

Is COVID-19 associated with latent toxoplasmosis?

The present study aimed to evaluate the possible association between coronavirus disease 2019 (COVID-19) and latent Toxoplasma gondii infection in a group of patients and healthy individuals. Blood samples were obtained from 269 PCR-positive COVID-19 patients. The serum was separated and tested for the existence of anti-T. gondii antibodies (IgG) using a commercial enzyme-linked immunosorbent assay kit. The prevalence of latent toxoplasmosis between a subgroup of the patients (aged under 55 years old) and COVID-19 negative individuals was compared. Anti-T. gondii antibodies were found in 226/269 (84.0%) patients with COVID-19. Anti-Toxoplasma antibodies were detected in 72/91 (79.1%) cases and 96/123 (78.0%) COVID-19 negative individuals (odd ratio = 1.1; 95% confidence interval: 0.55-2.07, P = 0.85). The median and interquartile range (IQR) of the IgG titer were not statistically significant different between case (97.3 [31.0-133.5]) and control groups (34.4 [13.0-144.5]) (P = 0.10). These findings demonstrated that latent Toxoplasma infection is prevalent amongst the COVID-19 patients. It also did not find any significant association between chronic toxoplasmosis and COVID-19.

Toxoplasma infection and risk of epilepsy: A case-control study of incident patients

We performed an age matched case-control study of incident epileptic patients to assess the relationship between Toxoplasma gondii seropositivity and epilepsy. Cases were 94 newly diagnosed patients (mean age, 36.7 ± 15.9) with unprovoked convulsive epilepsy of unknown etiology and controls were 88 healthy individuals (mean age, 37.5 ± 17.1) with no history of epilepsy or neurological disorders. Sera of all subjects were examined for anti-Toxoplasma IgG antibodies using commercially enzyme-linked immunoassays. We calculated odds ratios (ORs) and 95% confidence intervals (CIs) using univariate analysis and logistic regression, adjusted for potential confounders. The prevalence of anti-Toxoplasma IgG antibodies in epileptic patients (68.1%; 95%CI, 57.6-77.3%) was significantly higher than healthy controls (47.7%; 95%CI, 36.9-58.6%), indicating a significant relationship between Toxoplasma infection seropositivity and epilepsy (adjusted OR, 2.58; 95%CI, 1.16-5.72; P value < 0.05). The univariate analyses showed more than two-fold higher Toxoplasma seropositivity in patients with focal (OR, 2.31; 95%CI, 0.94-5.67) and generalized (OR, 2.35; 95%CI, 1.215-4.57) seizures versus healthy controls. Our findings support hypothesis that Toxoplasma infection/exposure may play an important role in development of epilepsy. Preventive measures to control of Toxoplasma infection especially in north of Iran and early treatment might be effective to reduce the occurrence of epilepsy in this region.

High Seroprevalence of Toxoplasma gondii in Slovenian Wild Boars (Sus scrofa)

Simple Summary

Toxoplasma gondii is a parasite that can cause serious disease in humans, especially in pregnant women. This parasite is found in many animals and people can be infected by eating raw or undercooked meat. Wild boar are known to harbor this parasite; populations and habitats have increased in the past decade, as it also increased the consumption of venison. The European population of wild boar has a mean prevalence of 26%. In our study, we found that the prevalence in the Slovenian wild boar population is 62%, the highest in the world to date. The prevalence was influenced by age and weight, but not by gender. In conclusion, the hunting community should be made aware of the high risk of parasite exposure when dealing with wild boar meat.

Abstract

Toxoplasma gondii is a zoonotic parasite of great public health concern. Wild boars could be considered an emerging source of toxoplasmosis in humans due to the popularity of venison and their increasing population. The aim of this study was to determine the seroprevalence of T. gondii in the Slovenian wild boar population and evaluate risk factors for human infection. Of 353 samples, 62% were positive for T. gondii using ELISA tests. This is the highest T. gondii seroprevalence reported to date in wild boar worldwide. The increase in prevalence with increasing age (p = 0.003) and weight (p = 0.002) were statistically significant, whereas gender was not (p = 0.781). Odds for being T. gondii-positive increased with age with the largest difference being between 2–3-year-old and 1–2-year-old animals (OR = 2.66, 95%CI: 1.03–6.85). Animals weighing 20–40 kg had a higher risk than animals weighing 0–20 kg (OR = 2.74, 95%CI: 1.21–6.20), whereas a further increase in the weight was not associated with increasing the odds. Due to the high Toxoplasma prevalence, the study concluded that the risk of exposure to T. gondii from handling raw or undercooked wild boar meat is high. Surveillance protocols should be established at the national level together with increased awareness within the hunting community.

Seroprevalence Estimates of Latent and Acute Toxoplasma Infections in HIV+ People-Call for Action in Underprivileged Communities

We undertook a comprehensive, systematic review of observational studies to estimate respective seroprevalences of latent and acute Toxoplasma gondii infections in HIV⁺ people at the global, regional and country levels; related seroprevalence to socio-economic variables and CD4+ cell counts; and assessed temporal changes in prevalence and risk factors for this group. We systematically searched international databases for seroepidemiological surveys between 1 January 1980 and 31 July 2020. We used a random effects model to calculate pooled seroprevalences with 95% confidence intervals (CI), and estimated the numbers of HIV⁺ people inferred to harbour latent and acute T. gondii infections (LT or AT). We grouped seroprevalence data according to the geographic regions defined by the World Health Organization (WHO) and conducted subgroup and meta-regression analyses of the data. Of a total of 4024 studies identified, 150 and 65 of them met the inclusion criteria for LT and AT in HIV⁺ people, respectively. The overall, pooled seroprevalences of LT and AT were 37.4% (95% CI, 33.4–41.4) and 1.3% (95% CI, 0.9–1.8%), equating to ~14.2 and 0.5 million HIV⁺ people, respectively. Most HIV⁺ people with T. gondii infections originated from Africa, and the highest seroprevalences were in low-income countries with low human development indices. Significant risk factors for toxoplasmosis in HIV⁺ patients included the consumption of raw/undercooked meat, frequent contact with soil, a low CD4+ T lymphocyte number (<200 cells per μL) and age. Overall, the finding of high seroprevalences of particularly latent T. gondii infection in HIV⁺ people in underprivileged regions of the world, such as parts of Africa, calls for preventative action. Programs that include routine serological monitoring, counselling, care, animal control and/or prophylactic treatment measures are needed to prevent severe toxoplasmosis from developing in people living with HIV infection. Our study highlights the potential importance of parasite chemoprophylaxis in resource-poor settings, particularly in low-income countries.

Serological Determination of Toxoplasma gondii among Sheep (Ovis aries) in Guilan Province, Iran

Toxoplasma gondii is one of the most common foodborne protozoan parasite causing congenital infection, abortion, and stillbirth in humans and animals. The temperate and humid climate is one of the most important factors in the high prevalence of T. gondii. Sheep are among the important sources of meat production in Guilan province, Iran. Therefore, the consumption of raw and half-cooked meat is one of the major risk factors for T. gondii infection. Toxoplasmosis in patients with intact immune systems is usually asymptomatic; however, it but can be life-threatening in patients with a weak immune system (for example, patients with the human immunodeficiency viruses/acquired immunodeficiency syndrome or cancer and transplant recipients). Guilan is divided into three geographical regions of plains with a temperate climatic condition, hillsides with a semi-humid climate, and heights with cold mountainous climate. Climate situations play a role in the prevalence of toxoplasmosis. The present study aimed to investigate the seroprevalence of T. gondii infection among sheep in Guilan province, north of Iran. In the current cross-sectional study, a total of 400 sheep sera samples were tested for the determination of immunoglobulin G (IgG) antibody against T. gondii using the enzyme-linked immunosorbent assay. The samples were divided into different groups according to the geographical location and animal age. T. gondii antibody (i.e., IgG) was detected in 166 sheep (41.5%). The highest frequency of T. gondii infection (72.7%; n=56) was observed for the age group of &amp;gt; 4 years; the difference was statistically significant in this regard (P=0.0001) in comparison to that reported for other groups. In addition, the seroprevalence of T. gondii was significantly higher in the plains (53.9%) than that of the hillsides and heights (P=0.0001). Consequently, the seroprevalence of T. gondii infection in Guilan was high indicating a significant relationship with geographical location and animal age.

Loop-Mediated Isothermal Amplification (LAMP) Assay to Detect Toxoplasmosis in Schizophrenia Patients

Background

Toxoplasma gondii (T. gondii) causes an important parasitic infection known as toxoplasmosis, which is a globally distributed important zoonosis. One of the major serious characteristics of T. gondii is its ability to manipulate the behavior of intermediate hosts. We performed a cross-sectional study to determine toxoplasmosis in schizophrenic patients, as one of the major neuropsychiatric disorders, using loop-mediated isothermal amplification (LAMP) technic by targeting parasite B1 gene.

Methods

Blood samples were taken from 118 schizophrenic patients hospitalized in tow hospitals including Baharan, Clinic of Psychiatric Ali-ibn-Abi-Talib Hospital (in Zahedan City), and Amir-al Momenin Psychiatric Hospital (in Zabol City), Sistan and Baluchestan Province, southeast Iran in 2016. They were analyzed using LAMP, and compared with the previous data of nested-PCR and serology.

Results

Out of the 118 schizophrenic individuals, 56 patients (47.4%) were found to be infected with T. gondii. The diagnosis of toxoplasmosis was confirmed in 41 patients (34.7%) via the nested-PCR. The seroprevalence of toxoplasmosis in schizophrenic patients was 55.9% (66/118).

Conclusion

We found a high efficiency of LAMP method in identifying toxoplasmosis and its high prevalence among schizophrenic patients. Our findings could provide viable offer implications for the prevention of schizophrenia.

An updated meta-analysis of the association between Toxoplasma gondii infection and risk of epilepsy

Toxoplasma gondii is a neurotropic pathogen with worldwide distribution. To evaluate the association between Toxoplasma infection and the risk of epilepsy by meta-analysis, observational peer-reviewed studies were retrieved from PubMed, Embase, Web of Science, Scopus and Google Scholar (up to 10 October 2018) and by reference review. Pooled risk estimates were calculated using a random effects model. Heterogeneity was assessed using Cochrane's Q-test and I2. In total, 16 eligible studies involving 19 data sets were included for the final analysis. A total 7897 participants (3771 epileptic patients, 4026 healthy controls) were included. The pooled odds ratio (OR) for Toxoplasma infection was increased to 1.72 (95% confidence interval [CI] 1.37 to 2.16) among patients with epilepsy. There was moderate heterogeneity among the studies (χ2=39.8, I2=62.3%, p=0.001). The ORs from subgroup analyses showed that both cryptogenic epilepsy (OR 2.65 [95% CI 1.91 to 3.68]) and active convulsive epilepsy (OR 1.37 [95% CI 1.09 to 1.72]) were significantly associated with Toxoplasma infection. Another subgroup analyses according to age showed a significant positive association in children (OR 1.33), adults (OR 1.57) and in all ages (OR 1.89). Our findings support the association between Toxoplasma infection and epilepsy. More prospective studies with larger sample sizes and more experimental studies are recommended to elucidate a causative relationship.

Occurrence of Toxoplasma gondii antibodies and associated risk factors in women in selected districts of Punjab province, Pakistan

Toxoplasmosis is a parasitic zoonotic disease caused by Toxoplasma (T.) gondii. Limited data are available on the occurrence of T. gondii in women especially pregnant women in Pakistan. The present study aimed to determine the occurrence and risk factors associated with T. gondii in pregnant and non-pregnant women in Punjab Province, Pakistan. A cross-sectional study was conducted and 593 samples were collected from pregnant (n = 293) and non-pregnant (n = 300) women of District Headquarter Hospitals of Chiniot, Faisalabad, Jhang and Okara, Pakistan. Data related to demographic parameters and risk factors were collected using a pretested questionnaire on blood sampling day. Serum samples were screened for antibodies (IgG) against T. gondii using ELISA. A univariant and binomial logistic regression was applied to estimate the association between seropositive and explanatory variables considering the 95% confidence interval. P value ⩽0.05 was considered statistically significant for all analysis. Out of 593, 44 (7.42%) women were seropositive for T. gondii IgG antibodies. Occupation, age, sampling location, socioeconomic status, contact with cat, pregnancy status and trimester of pregnancy were significantly associated with seropositivity for T. gondii antibodies. Location and trimester of pregnancy were identified as potential risk factors for T. gondii seropositivity based on binomial logistic regression. Toxoplasma gondii is prevalent in pregnant and non-pregnant women. Therefore, now a necessitated awareness is required to instruct the individuals about these infectious diseases (toxoplasmosis) and their control strategies to maintain the health of human population. Moreover, health awareness among public can help the minimization of T. gondii infection during pregnancy and subsequent risk of congenital toxoplasmosis.

Seroepidemiology, modifiable risk factors and clinical symptoms of Toxocara spp. infection in northern Iran

Toxocariasis is one of the most important and widespread neglected tropical infectious diseases. We designed a cross-sectional study to assess the seroepidemiological aspects of toxocariasis among the general population in northern Iran. A total of 630 rural subjects were enrolled to participate in the study. The presence of anti-Toxocara immunoglobulin G (IgG) was tested using a commercially available enzyme-linked immunosorbent assay. A structured questionnaire was also used to evaluate the potential risk factors and related clinical signs/symptoms. The presence of anti-Toxocara IgG antibodies was detected in 148 of the 630 rural subjects (23.5% [95% confidence interval {CI} 21.8 to 25.1]). By multivariate analysis, age (odds ratio [OR] 2.89 [95% CI 1 to -8.3], p=0.04), eating improperly washed vegetables (OR 4.05 [95% CI 2.47 to 6.64], p<0.001), contact with dogs (OR 3.31 [95% CI 2.13 to 5.12], p<0.001) and exposure to soil (OR 3.56 [95% CI 2.13 to 5.13], p<0.001) were significantly associated with the seroprevalence of Toxocara. The clinical study also demonstrated that the seroprevalence of Toxocara infection was significantly associated with asthma (OR 3.78 [95% CI 1.63 to 8.75], p<0.001) and ophthalmic disorder (OR 1.83 [95% CI 1.04 to 3.21], p=0.034). The findings proved that residents of rural communities in tropical regions may be heavily exposed to Toxocara spp. We highly recommend more investigations in high-risk groups.

Global prevalence of latent toxoplasmosis in pregnant women: a systematic review and meta-analysis

BACKGROUND

Toxoplasma gondii infection, if acquired as an acute infection during pregnancy, can have substantial adverse effects on mothers, fetuses and newborns. Latent toxoplasmosis also causes a variety of pathologies and has been linked to adverse effects on pregnancy.

OBJECTIVE

Here, we present results of a comprehensive systematic review and meta-analysis of the global prevalence of latent toxoplasmosis in pregnant women.

DATA SOURCE

We searched PubMed, EMBASE, Web of Science, SciELO and Scopus databases for relevant studies that were published between 1 January 1988 and 20 July 2019.

STUDY ELIGIBILITY CRITERIA

All population-based, cross-sectional and longitudinal studies reporting the prevalence of latent toxoplasmosis in healthy pregnant women were considered for inclusion.

PARTICIPANTS

Pregnant women who were tested for prevalence of latent toxoplasmosis.

INTERVENTIONS

There were no interventions.

METHOD

We used a random effects model to calculate pooled prevalence estimates with 95% confidence intervals (CIs). We grouped prevalence data according to the geographic regions defined by the World Health Organization (WHO). Multiple subgroup and meta-regression analyses were performed.

RESULTS

In total, 311 studies with 320 relevant data sets representing 1 148 677 pregnant women from 91 countries were eligible for inclusion in the meta-analysis. The global prevalence of latent toxoplasmosis in pregnant women was estimated at 33.8% (95% CI, 31.8-35.9%; 345 870/1 148 677). South America had the highest pooled prevalence (56.2%; 50.5-62.8%) of latent toxoplasmosis in pregnant women, whereas the Western Pacific region had the lowest prevalence (11.8%; 8.1-16.0%). A significantly higher prevalence of latent toxoplasmosis was associated with countries with low income and low human development indices (p < 0.001).

CONCLUSION

Our results indicate a high level of latent toxoplasmosis in pregnant women, especially in some low- and middle-income countries of Africa and South America, although the local prevalence varied markedly. These results suggest a need for improved prevention and control efforts to reduce the health risks to women and newborns.

Associations of mental disorders and neurotropic parasitic diseases: a meta-analysis in developing and emerging countries

BACKGROUND

Although they are declining worldwide, neurotropic parasitic diseases are still common in developing and emerging countries. The aim of this study was to estimate the pooled prevalence and pooled association measures of comorbidities between mental disorders (anxiety, depression, bipolar disorder, and schizophrenia) and neurotropic parasitic diseases (malaria, cysticercosis, toxoplasmosis, human African trypanosomiasis, Chagas disease, and human toxocariasis) in developing and emerging countries.

METHODS

As the first meta-analysis on this topic, this study was performed in accordance with PRISMA guidelines. The protocol was registered in PROSPERO (N°CRD42017056521). The Medline, Embase, Lilacs, and Institute of Epidemiology and Tropical Neurology databases were used to search for articles without any restriction in language or date. We evaluated the quality of studies independently by two investigators using the Downs and Black assessment grid and pooled estimates using the random-effects method from CMA (Comprehensive Meta Analysis) Version 3.0.

RESULTS

In total, 18 studies published between 1997 and 2016 met our inclusion criteria. We found that the prevalence of anxiety and depression in people suffering from Chagas disease and/or neurocysticercosis was 44.9% (95% CI, 34.4-55.9). In 16 pooled studies that included 1782 people with mental disorders and 1776 controls, toxoplasmosis and/or toxocariasis were associated with increased risk of schizophrenia and/or bipolar disorders (odds ratio = 2.3; 95% CI, 1.7-3.2). Finally, toxocariasis and/or toxoplasmosis were associated with an increased risk of the onset of schizophrenia (odds ratio = 2.4; 95% CI, 1.7-3.4).

CONCLUSION

Our pooled estimates show that the associations between diseases studied are relatively high in developing and emerging countries. This meta-analysis supports the hypothesis that toxoplasmosis could be the cause of schizophrenia. These findings could prove useful to researchers who want to further explore and understand the associations studied.

Acute Toxoplasma infection in pregnant women worldwide: A systematic review and meta-analysis

BACKGROUND

Acute Toxoplasma infection (ATI) during pregnancy, if left untreated, can cause severe adverse outcomes for the fetus and newborn. Here, we undertook a meta-analysis to estimate the worldwide prevalence of ATI in pregnant women.

METHODS

We searched international databases for studies published between January 1988 and November 2018. We included population-based cross-sectional and prospective cohort studies that reported the prevalence of ATI in pregnant women. Data were synthesized using a random effect model to calculate the overall prevalence of ATI (with a 95% CI) in six WHO regions and globally. We also performed linear meta-regression analyses to investigate associations of maternal, socio-demographic, geographical and climate parameters with the prevalence of ATI.

RESULTS

In total, 217 studies comprising 902,228 pregnant women across 74 countries were included in the meta-analysis. The overall prevalence of ATI in pregnant women globally was 1.1% (95% CI: 0.9-1.2%). In studies where more strict criteria for ATI were used, the overall prevalence was 0.6% (95% CI: 0.4-0.7%). The prevalence was highest in the Eastern Mediterranean region (2.5%; 95%CI: 1.7-3.4%) and lowest in the European region (0.5%; 95% CI: 0.4-0.7%). A significantly higher prevalence of ATI was found in countries with lower income levels (P = 0.027), lower human development indices (P = 0.04), higher temperatures (P = 0.02) and lower latitudes (P = 0.005) and longitudes (P = 0.02).

CONCLUSIONS

The risk of acquiring ATI during gestation is clinically important and preventive measures to avoid exposure of pregnant women to Toxoplasma infection should be strictly applied.

Toxoplasma gondii seropositivity associated to peri-urban living places in pregnant women in a rural area of Buenos Aires province, Argentina

Infection with Toxoplasma gondii is very common in humans throughout the world, the intake of raw or undercooked meat with tissue cysts and fruits, vegetables and water contaminated with parasite oocysts being the main routes of infection. Here, we analyzed the seroprevalence of anti-T. gondii antibodies in pregnant females (age 13–44 years; n = 920) between April 2014 and December 2017 from Chascomús (Argentina), a city immersed in a rural area. Altogether 320 tested positive for immunoglobulin G antibodies, yielding an overall seroprevalence of 34.8% (CI 95%: 31.7–37.9). No association was observed between seropositivity and age. In addition, by using the QGIS 3.2.1 software we analyzed the geographical distribution of 769 (83.6%) pregnant females in two main areas of the city: Urban (n = 157) and Peri-urban (n = 612) with a seroprevalence of 26.8% (CI 95%: 19.8–33.7) and 36.4% (CI 95%: 32.6–40.3) respectively, and this difference was statistically significant (p = 0.023). Furthermore, we assessed through a questionnaire survey, between April 2016 to December 2017, possible risk factors such as activity (urban and rural), home water supply, animal husbandry, presence of cats as pets, gardening and consumption of meat and its derivatives (pork, sheep meat and sausages) and their frequencies (consumption per week), not finding significant association with seropositivity. Significant differences was found when the seroprevalence was analyzed between the urban and peri-urban neighborhoods of the city of Chascomús. The higher seroprevalence in peri-urban neighborhoods could be due to an unfavorable socioeconomic situation and/or to undeveloped peri-urban environments, which is a risk factor that should be taken into account when planning the health care of pregnant females.

Immunodiagnosis and molecular validation of Toxoplasma gondii infection among patients with end-stage renal disease undergoing haemodialysis

Infection is a significant cause of morbidity and mortality in patients with chronic kidney disease, especially who were under dialysis due to their depressed immunity. Toxoplasma gondii is a ubiquitous parasite that causes severe manifestations in immunocompromised patients. This case-control study was conducted to the immunodiagnosis and molecular validation of T. gondii infection among patients with end-stage renal disease undergoing haemodialysis. The study population consisted of 260 haemodialysis patients and 259 healthy controls referred to the main dialysis centres of Tehran, Iran during 2016. Anti-T. gondii immunoglobulin G (IgG) and immunoglobulin M (IgM) antibodies were assessed using enzyme-linked immunosorbent assay. As well, the T. gondii genomic DNA in whole blood samples of IgM-positive patients and healthy controls was evaluated using GRA6-polymerase chain reaction (PCR) and SAG1-loop-mediated isothermal amplification (LAMP) assays. The anti-T. gondii IgG and IgM antibodies were detected in 175 (67.3%) and 18 (7%) of haemodialysis patients and 122 (47%) and 4 (1.5%) of controls, respectively. Two of the 18 blood samples from IgM-positive patients and none of the IgM-positive control subjects were positive by GRA6-PCR. Whereas, nine and two blood samples of IgM-positive patients and controls were positive for Toxoplasma DNA by a SAG1-LAMP technique respectively. The seropositivity of the Toxoplasma IgM antibody was significantly different between haemodialysis patients and healthy controls which was confirmed by PCR and LAMP. The higher prevalence of T. gondii infection in haemodialysis patients compared with the controls proposes that these patients can be a group at risk for toxoplasmosis and screening for toxoplasmosis before dialysis is necessary for the patients.

Toxoplasma gondii infection and risk of Parkinson and Alzheimer diseases: A systematic review and meta-analysis on observational studies

In the past decade, Toxoplasma gondii infection has been recognized as a potential risk for many psychiatric and neurological disorders. We performed this systematic review and meta-analysis to evaluate the association between Toxoplasma infection and Parkinson's and Alzheimer's diseases. PubMed, Web of science, Scopus and Embase databases were searched up to September 30, 2018 for studies that reported risk of Parkinson's and Alzheimer's diseases associated with Toxoplasma infection. We used a random effects meta-analysis model to generate the pooled odds ratio (OR) with 95% confidence intervals (CIs). Eleven studies, including seven studies for Parkinson's disease (428 patients and 540 controls) and four studies for Alzheimer's disease (301 patients and 313 controls), were included in the meta-analysis. We found that there was no statistically significant association between Toxoplasma infection, as determined by IgG serology, IgM serology, and PCR with increased risk of Parkinson's disease (OR, 1.14; 95% CI, 0.78-1.68), (OR, 1.61; 95% CI, 0.33-7.76) and (OR, 1.87; 95% CI, 0.43-8.05), respectively. The OR for association of Toxoplasma infection, based on IgG serology with Alzheimer's patients, compared to control group, was (OR, 1.38; 95% CI, 0.99-1.92), demonstrating a marginally significant association between Toxoplasma infection and Alzheimer's disease. Our findings do not support a general hypotheses regarding an associative relationship between Toxoplasma infection and Parkinson's disease, but do support a marginally significant association between Toxoplasma infection and Alzheimer's disease; this association should be investigated further through longitudinal and experimental studies.

Exposure to Ascaris lumbricoides infection and risk of childhood asthma in north of Iran

BACKGROUND

Asthma and Ascaris lumbricoides infection are common health issues affecting 250 and 700 million people worldwide, respectively. The relationship between ascariasis and asthma is a matter of substantial interest and research.

METHODS

We performed a case-control study to evaluate whether the exposure to Ascaris infection is associated with asthma in children. We also assessed potential risk factors for Ascaris infection and asthma in study area. We enrolled 145 asthmatic children and 115 healthy controls. The Global Initiative for Asthma guideline was used to evaluate asthma symptoms and severity in study participants. Ascaris infection was assessed by the presence of anti-Ascaris IgG ≥ 11 IU/mL measured by enzyme-linked immunosorbent assay.

RESULTS

We have found a significant relationship between exposure to Ascaris and asthma (odds ratio, 2.92; 95% CI 1.04-8.18; P value = 0.034), and this relationship remained significant after adjustment for covariates (adjusted OR, 3.36; 95% CI 1.04-13%; P value = 0.047). Ascaris infection was more frequent in children with mild sustainable asthma (13.2%; 15/113) than in children with moderate sustainable asthma (6.2%, 2/32), although there was a non-significant difference between these groups (OR, 2.3; 95% CI 0.5-10.1; P value = 0.35). Based on results of a multi-regression analysis, contact with soil (OR, 6.7; 95% CI 1.9-23.5), and drinking unsafe water (OR, 4.2; 95% CI 1.2-14.2) were significant risk factors for Ascaris infection in the study area.

CONCLUSION

Results of this study suggest that A. lumbricoides infection might affect susceptibility to asthma in children. These results could be useful in prevention, early diagnosis and management of childhood asthma.

The global seroprevalence of Toxoplasma gondii in pigs: A systematic review and meta-analysis

Toxoplasmosis, caused by the protozoan parasite Toxoplasma gondii, is an important disease with worldwide distribution. Infection can occur from ingesting raw or undercooked infected meat, and among food animal species, pork is known to be one of the main sources of meat-borne infection. Here, we present results of the first systematic review and meta-analysis on the global T. gondii seroprevalence in pigs. PubMed/MEDLINE, Scopus, and EMBASE databases were comprehensively searched for relevant studies published between January 1, 1990 and October 25, 2018. We used a random effects model to calculate pooled seroprevalence estimates with 95% confidence intervals (CI) and analyzed data from five continents. We also conducted subgroup and meta-regression analyses to evaluate the effects of geographical and climate variables on pooled seroprevalence rates. Among 1542 publications identified, 148 studies containing 150 datasets were included in the meta-analysis, and comprised 148,092 pigs from 47 countries. The pooled global T. gondii seroprevalence in pigs was estimated to be 19% (95%CI, 17-22%; 23,696/148,092), with the lowest seroprevalence in Europe (13%; 10-15%) and highest seroprevalence in Africa (25%; 17-34%) and North America (25%; 19-33%). The seropositivity rates in Asia and South America regions were (21%, 16-26%) and (23%; 17-30%), respectively. A significantly higher T. gondii seroprevalence was associated with higher mean annual temperature and lower geographical latitude. The presence of cats on farms was identified as a potential risk factor for T. gondii seropositivity (OR, 1.41; 95%CI, 1.00-2.02). Our findings highlight the importance of pigs as a possible source of human T. gondii infections.

The Association between Toxoplasma gondii Infection and Risk of Parkinson's Disease: A Systematic Review and Meta-Analysis

Background

Several studies have investigated the association between Toxoplasma gondii (T. gondii) infection and risk of Parkinson's disease (PD) with inconsistent results. Clarifying this relation might be useful for better understanding of the risk factors and the relevant mechanisms of PD, thus a meta-analysis was conducted to explore whether exposure to T. gondii is associated with an increased risk of PD.

Methods

We conducted this meta-analysis according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. A rigorous literature selection was performed by using the databases of PubMed, Embase, Web of Science, Cochrane Library, and ScienceDirect. Odds ratio (OR) and corresponding 95% confidential interval (CI) were pooled by using fixed-effects models. Sensitivity analysis, publication bias test, and methodological quality assessment of studies were also performed.

Results

Seven studies involving 1086 subjects were included in this meta-analysis. Pooled data by using fixed-effects models suggested both latent infection (OR, 1.17; 95% CI, 0.86 to 1.58; P=0.314) and acute infection (OR, 1.13; 95% CI, 0.30 to 4.35; P=0.855) were not associated with PD risk. Stable and robust estimates were confirmed by sensitivity analysis. No publication bias was found by visual inspection of the funnel plot, Begg's, and Egger's test.

Conclusions

This meta-analysis does not support any possible association between T. gondii infection and risk of PD. Researches are still warranted to further explore the underlying mechanisms of T. gondii in the pathogenesis of PD and their causal relationship.

Seroepidemiological evaluation of Toxoplasma gondii immunity among the general population in southwest of Iran

Toxoplasmosis is a cosmopolitan zoonotic infection, caused by a unicellular protozoan parasite known as Toxoplasma gondii (T. gondii) that belongs to the phylum Apicomplexa. The present investigation was aimed to evaluate the seroprevalence of T. gondii infection in the general population of Abadan city. In this cross-sectional study, a total of 496 subjects were participated. Anti-T. gondii IgG and IgM antibodies were tested using commercially available enzyme-linked immunosorbent assay (ELISA). Moreover, a structured questionnaire was completed for each person. Out of 496 subjects, 188 (37.9%) and 30 (6.05%) samples were seropositive for IgG and IgM, respectively. The more seroprevalence was found during spring season, among female subjects, in rural inhabitants, in persons with the education level of diploma or lower, from the subjects with a history of contact with cat, in individuals who consumed raw/undercooked meat, and amongst who drink unpurified water. The results showed that inhabitants of tropical areas, may be moderately exposed to T. gondii. Increase of knowledge of people about toxoplasmosis, certainly affects in reduction of the infection.

A systematic review and meta-analysis of the prevalence of toxoplasmosis in hemodialysis patients in Iran

OBJECTIVES

Toxoplasmosis is a parasitic disease that occurs worldwide, with a wide range of complications in immunocompromised patients. This systematic review and meta-analysis was performed to evaluate the seroprevalence of Toxoplasma gondii among patients undergoing hemodialysis in Iran.

METHODS

We searched English and Persian databases for studies reporting T. gondii seroprevalence in Iranian hemodialysis patients through December 31, 2017. Inclusion and exclusion criteria were applied.

RESULTS

A total of 10 studies containing 1,865 participants (1,048 patients and 817 controls) met the eligibility criteria. Immunoglobulin G (IgG) antibodies against T. gondii were found in 58% (95% confidence interval [CI], 46 to 70) of hemodialysis patients and 40% (95% CI, 31 to 50) of healthy controls, while immunoglobulin M (IgM) antibodies were found in 2% (95% CI, 0 to 6) of hemodialysis patients and 0% (95% CI, 0 to 1) of healthy controls. The meta-analysis showed that hemodialysis patients were significantly more likely to be seropositive for IgG (odds ratio [OR], 2.04; 95% CI, 1.54 to 2.70; p<0.001) and IgM (OR, 2.53; 95% CI, 1.23 to 5.22; p<0.001) antibodies against T. gondii infection than healthy individuals.

CONCLUSIONS

The current study revealed a high prevalence of T. gondii infection in hemodialysis patients. Since hemodialysis patients are immunocompromised and T. gondii can cause serious clinical complications, we recommend that periodic screenings for T. gondii infection should be incorporated into the routine clinical care of these patients.

Toxoplasma gondii in Blood Donors: A Study in Boyer-Ahmad County, Southwest Iran

Toxoplasma gondii is an important foodborne protozoan that can be transmitted through infected blood containing tachyzoite form of the parasite. The current study aimed to evaluate the prevalence of T. gondii infection and related risk factors among healthy blood donors in Boyer-Ahmad County, southwest Iran. Blood samples were taken from 285 healthy blood donors who voluntarily agreed to participate in this study. Sera and buffy coat were isolated from the blood samples for serological and molecular evaluations. The sera were tested for anti-T. gondii antibodies (both IgG and IgM), using a commercial ELISA kit. The buffy coat of seropositive cases was evaluated for detection of T. gondii DNA by PCR. Moreover, a structured questionnaire, containing socioepidemiological data and possible risk factors, was filled out by each participant during sample collection. Anti-T. gondii antibodies were detected in sera of 48/285 (16.8%) participants. Only two of the subjects (0.7%) were seropositive for both IgG and IgM antibodies. T. gondii DNA was not detected in buffy coat of any of the seropositive cases. Risk factors such as contact with soil (OR, 9.7; 95% CI, 4.9–19.4) and consumption of semicooked meat (OR, 2.5; 95% CI, 1.2–5.03) were statistically associated with seropositivity to T. gondii. The seroprevalence rate of T. gondii antibodies in the blood donors of Boyer-Ahmad County was not high in comparison with other regions in Iran. In this study, consumption of undercooked meats, job, and contact with soil were independent risk factors associated with T. gondii infection, which can be considered as potential sources of T. gondii infection.

Advances in serological, imaging techniques and molecular diagnosis of Toxoplasma gondii infection

BACKGROUND

Toxoplasmosis is worldwide distributed zoonotic infection disease with medical importance in immunocompromised patients, pregnant women and congenitally infected newborns. Having basic information on the traditional and new developed methods is essential for general physicians and infectious disease specialists for choosing a suitable diagnostic approach for rapid and accurate diagnosis of the disease and, consequently, timely and effective treatment.

METHODS

We conducted English literature searches in PubMed from 1989 to 2016 using relevant keywords and summarized the recent advances in diagnosis of toxoplasmosis.

RESULTS

Enzyme-linked immunosorbent assay (ELISA) was most used method in past century. Recently advanced ELISA-based methods including chemiluminescence assays (CLIA), enzyme-linked fluorescence assay (ELFA), immunochromatographic test (ICT), serum IgG avidity test and immunosorbent agglutination assays (ISAGA) have shown high sensitivity and specificity. Recent studies using recombinant or chimeric antigens and multiepitope peptides method demonstrated very promising results to development of new strategies capable of discriminating recently acquired infections from chronic infection. Real-time PCR and loop-mediated isothermal amplification (LAMP) are two recently developed PCR-based methods with high sensitivity and specificity and could be useful to early diagnosis of infection. Computed tomography, magnetic resonance imaging, nuclear imaging and ultrasonography could be useful, although their results might be not specific alone.

CONCLUSION

This review provides a summary of recent developed methods and also attempts to improve their sensitivity for diagnosis of toxoplasmosis. Serology, molecular and imaging technologies each has their own advantages and limitations which can certainly achieve definitive diagnosis of toxoplasmosis by combining these diagnostic techniques.

The Seroprevalence and Risk Factors of Toxoplasmosis Among Female Undergraduate University Students in Saudi Arabia

Objectives

Toxoplasma gondii (T. gondii) is a serious public health issue, but limited data has been published to date on the seroprevalence of T. gondii infection in Saudi Arabia. Therefore, this study aimed to establish the seroprevalence and risk factors of T. gondii infection using a sample of females enrolled at a university in Northern Saudi Arabia.

Methods

Using a cross-sectional research approach, we recruited a convenience sample of 180 healthy females studying at the University of Tabuk between February and June 2016. We used a questionnaire to gather sociodemographic data on the participants to establish the risk factors leading to exposure to toxoplasma. Blood samples were taken from the participants and analyzed to detect T. gondii antibodies (immunoglobulin M and immunoglobulin G) via the enzyme-linked immunosorbent assay technique. Multivariate logistic regression modeling was employed to establish the potential predictor variables for T. gondii infection.

Results

Of the 180 participants, 17 (9.4%) were seropositive for T. gondii IgG. None tested positive for IgM antibodies exclusively. The sole variable positively associated with seropositive T. gondii IgG was the participants' consumption of raw, unwashed fruit or vegetables (odds ratio = 3.36, 95% confidence interval: 1.11-10.22).

Conclusions

Our findings emphasize the need for higher awareness of toxoplasmosis in Saudi Arabia, specifically knowledge of the way toxoplasma infection occurs so that women can more easily avoid it. Large-scale research is therefore required to inform the design of future public health interventions.

Parkinson's disease and Toxoplasma gondii infection: Sero-molecular assess the possible link among patients

We investigated the possible association between Parkinson's disease (PD), the second most common neurodegenerative disorder and Toxoplasma gondii infection, the most common neurotropic protozoan parasitic infection, using serological and molecular techniques. One hundred and fifteen patients with confirmed PD and 115 healthy subjects in the same age and sex distribution were enrolled in this study. Blood samples were taken from each participant and the sera was screened for anti-Toxoplasma antibodies (IgG and IgM). PCR assay was performed in duplicate using the primer pair targeting the B1 gene of Toxoplasma. Amplicons were directly sequenced to conduct the phylogenetic analysis. The prevalence of Toxoplasma infection based on IgG titer was 53% in case and 55.6% in the control groups, revealing no statistically significant association between Toxoplasma seropositivity and PD (OR=0.90; 95% CI=0.54-1.51; P=0.691). According to PCR assay, the prevalence of Toxoplasma infections was 19.3% in the case and 10.4% in control groups which the difference was statistically significant (OR=3.02; 95% CI=1.46-6.27; P=0.002). Multiple sequence alignment of Toxoplasma gondii isolates manifested a common haplotype by the identity: 93.6-100% and divergence: 0-6.7%. We concluded that T. gondii infection not only could not be a risk factor to PD, but even it could be concluded that patients with PD are in more risk to acquisition of infection. These results provide fresh insights into the ambiguous association between T. gondii infection and PD.

The global seroprevalence of Toxoplasma gondii among wild boars: A systematic review and meta-analysis

This systematic review and meta-analysis study was performed to evaluate the worldwide seroprevalence of Toxoplasma gondii among wild boar. We searched PubMed, Science Direct, Web of Science, Cochrane, Scopus, EBSCOhost and Google Scholar databases for studies reporting T. gondii seroprevalence in wild boars between January 1995 and March 2017. Inclusion and exclusion criteria were applied. We estimated the pooled seroprevalence of T. gondii in wild boars using a random-effects model, and evaluated overall seroprevalence in different geographical areas. A total of 43 articles that included 16788 wild boar from 23 countries fulfilled our eligibility criteria. Of these, 4759 wild boar had been defined T. gondii seropositive and we estimated the pooled worldwide seroprevalence of toxoplasmosis in wild boars to be 23% (95% CI: 19-27%). The pooled seroprevalence in North America (32%, 20-45%; odds ratio [OR] 2.09) and Europe (26%, 21-30%; OR 1.72), was higher than Asia (13%, 5-23%). The lowest seroprevalence was estimated in South America (5%, 3-8%). An increased seropositivity was observed with elevation in geographical latitude. In subgroup analyses, the pooled seroprevalence of T. gondii was higher in wild boar older than 12 months of age (28%, 22-35%; OR 1.57) compared to those up to 12 months of age (20%, 16-25%). Our findings suggest that wild boar have an important role in human infection and the epidemiological cycle of T. gondii infection.

Human infectious diseases and risk of preeclampsia: an updated review of the literature

BACKGROUND

Preeclampsia (PE) is one of the major causes of maternal and perinatal morbidity and mortality, especially in low- and middle-income countries. In recent years, a growing body of literatures suggests that infections by bacteria, viruses, and parasites and their related inflammations play an important role in the pathogenesis of PE.

METHODS

We searched PubMed, Google scholar, and Cochrane databases using the following search words: "infection and preeclampsia," "bacterial infection and preeclampsia," "viral infection and preeclampsia" and "parasitic infection and preeclampsia."

RESULTS

The literature review revealed that many bacteria including Helicobacter pylori, Chlamydia pneumonia, and those are involved in periodontal disease or urinary tract infections (UTIs) and some viral agents such as Cytomegalovirus, herpes simplex virus type-2, human immunodeficiency virus, and some parasites especially Plasmodium spp. and Toxoplasma gondii can be effective in development of PE. Inflammation responses against infections has major role in the inducement of PE. The shift of immunological cytokine profile of Th2 toward Th1 and high levels of pro-inflammatory cytokines (TNF-ɑ, IL-12, IFN-γ, etc.), increase of oxidative stress, increase of anti-angiogenic proteins, increase of vascular endothelial growth factor receptor 1 (sVEGFR1), and complement C5a are the main potential mechanisms related to infections and enhanced development of PE.

CONCLUSION

Thus, early diagnosis and treatment of bacterial, viral, and parasitic infections could be an effective strategy to reduce the incidence of PE.