Toxocara spp. infection and risk of childhood asthma: A systematic review and meta-analysis

Understanding the research and practical needs required to control toxocariasis in Iran

Human toxocariasis (HT) is a widespread zoonotic infection globally, notably prevalent in tropical areas. Enhancing our understanding of toxocariasis can lead to increased attention towards the socioeconomic impact and control of this neglected zoonosis. We conducted a comprehensive review of all available articles and official documents on toxocariasis in Iran to identify research gaps and critical needs for its control. This review highlights that despite numerous studies exploring various aspects of toxocariasis in definitive and paratenic hosts, as well as humans and environmental contamination, significant data deficiencies and gaps persist across different regions in the country. These gaps involve investigating the worm burden and reinfection rates in definitive hosts, developing more sensitive methods to detect and differentiate of Toxocara species, and understanding the behavior of definitive host animals. Additionally, identifying potential paratenic hosts for HT and exploring the organ-specific affinity and survival duration of Toxocara larvae within these hosts are essential areas for exploration. It's also imperative to comprehend the sylvatic and domestic cycles of the parasite in paratenic hosts. Furthermore, assessing egg density in the environment, exploring potential new sources such as water, and identifying regions with optimal climatic conditions for the survival and development of Toxocara eggs are crucial for the formulation of effective prevention and control strategies. Identifying at-risk groups, developing early diagnosis techniques, employing imaging methods, and identifying long-term complications in humans are also crucial. Community health organizations should prioritize health education for the public and professionals. Furthermore, accurately estimating definitive host populations, monitoring and preventing their movements in public places, implementing regular deworming practices for pets and stray hosts, and recognizing the infection's significance as a health priority are critical. This comprehensive understanding advocates for a holistic "one health" approach to control of HT.

Efficacy of artemether against toxocariasis in mice: parasitological and immunopathological changes in brain, liver, and lung

Toxocariasis is a zoonosis that represents a serious threat to public health particularly in tropical and subtropical areas. Currently, albendazole, the most effective drug for treating visceral toxocariasis, shows moderate efficacy against the larvae in tissues and has some adverse effects. Artemether is an antiparasitic drug mainly used in the treatment of malaria and showed effectiveness against numerous helminthic infections. Besides, it possesses potent anti-inflammatory, antiapoptotic, antifibrotic, and neuroprotective properties. Thus, the study's aim was to investigate artemether's effects in comparison with albendazole on the therapeutic outcome of experimental toxocariasis. For this aim, 140 laboratory-bred mice were divided into four main groups: uninfected control, treatment control, albendazole-treated, and artemether-treated groups. The treatment regimens were started at the 15th dpi (early treatment), and at the 35th dpi (late treatment). The effectiveness of treatment was determined by brain larval count, histopathological, immunohistochemical, and biochemical examination. Artemether showed more effectiveness than albendazole in reducing brain larval counts, markers of brain injury including NF-κB, GFAP, and caspase-3, the diameter and number of hepatic granulomas, hepatic oxidative stress, hepatic IL-6, and TG2 mRNA, and pulmonary inflammation and fibrosis. The efficacy of artemether was the same when administered early or late in the infection. Finally, our findings illustrated that artemether might be a promising therapy for T. canis infection and it could be a good substitution for albendazole in toxocariasis treatment.

Microbes little helpers and suppliers for therapeutic asthma approaches

Bronchial asthma is a prevalent and increasingly chronic inflammatory lung disease affecting over 300 million people globally. Initially considered an allergic disorder driven by mast cells and eosinophils, asthma is now recognized as a complex syndrome with various clinical phenotypes and immunological endotypes. These encompass type 2 inflammatory endotypes characterized by interleukin (IL)-4, IL-5, and IL-13 dominance, alongside others featuring mixed or non-eosinophilic inflammation. Therapeutic success varies significantly based on asthma phenotypes, with inhaled corticosteroids and beta-2 agonists effective for milder forms, but limited in severe cases. Novel antibody-based therapies have shown promise, primarily for severe allergic and type 2-high asthma. To address this gap, novel treatment strategies are essential for better control of asthma pathology, prevention, and exacerbation reduction. One promising approach involves stimulating endogenous anti-inflammatory responses through regulatory T cells (Tregs). Tregs play a vital role in maintaining immune homeostasis, preventing autoimmunity, and mitigating excessive inflammation after pathogenic encounters. Tregs have demonstrated their ability to control both type 2-high and type 2-low inflammation in murine models and dampen human cell-dependent allergic airway inflammation. Furthermore, microbes, typically associated with disease development, have shown immune-dampening properties that could be harnessed for therapeutic benefits. Both commensal microbiota and pathogenic microbes have demonstrated potential in bacterial-host interactions for therapeutic purposes. This review explores microbe-associated approaches as potential treatments for inflammatory diseases, shedding light on current and future therapeutics.

Who Let the Dogs Out? Unmasking the Neglected: A Semi-Systematic Review on the Enduring Impact of Toxocariasis, a Prevalent Zoonotic Infection

Toxocariasis remains an important neglected parasitic infection representing one of the most common zoonotic infections caused by the parasite Toxocara canis or, less frequently, by Toxocara cati. The epidemiology of the disease is complex due to its transmission route by accidental ingestion of embryonated Toxocara eggs or larvae from tissues from domestic or wild paratenic hosts. Even though the World Health Organization and Centers for Disease Control classified toxocariasis amongst the top six parasitic infections of priority to public health, global epidemiological data regarding the relationship between seropositivity and toxocariasis is limited. Although the vast majority of the infected individuals remain asymptomatic or experience a mild disease, the infection is associated with important health and socioeconomic consequences, particularly in underprivileged, tropical, and subtropical areas. Toxocariasis is a disease with multiple clinical presentations, which are classified into five distinct forms: the classical visceral larva migrans, ocular toxocariasis, common toxocariasis, covert toxocariasis, and cerebral toxocariasis or neurotoxocariasis. Anthelmintic agents, for example, albendazole or mebendazole, are the recommended treatment, whereas a combination with topical or systemic corticosteroids for specific forms is suggested. Prevention strategies include educational programs, behavioral and hygienic changes, enhancement of the role of veterinarians, and anthelmintic regimens to control active infections.

Review of Toxocariasis at a Children's Hospital Prompting Need for Public Health Interventions

BACKGROUND

Toxocariasis, caused the by dog and cat roundworm, is one of the most common zoonotic helminth infections in the United States and can lead to severe lifelong morbidity in children. Although historical seroprevalence studies have identified a high frequency of toxocariasis regionally in the United States, there are few studies linking epidemiology and clinical disease in children. The study objective was to examine the contemporary epidemiology of pediatric toxocariasis within an endemic US region.

METHODS

We conducted an epidemiologic study analyzing children diagnosed with toxocariasis presenting to a tertiary pediatric hospital in Texas from 2010 to 2021. We examined risk factors and performed a geospatial analysis, including a comparative analysis of human cases and locations of surrendered infected stray animals in the same region.

RESULTS

Children diagnosed with toxocariasis were most commonly of Hispanic/Latino ethnicity (30/46; 65%), white race (41/45; 91%) and receiving Medicaid (34/44, 77%). Many infected children had contact with dogs or cats. Ocular toxocariasis was associated with a lack of peripheral eosinophilia ( P < 0.001). No other Toxocara syndromes were associated with defined absolute eosinophil count levels. Post-treatment resolution of eosinophilia was variable, ranging from 1 to 172 weeks. A Toxocara hotspot was identified in northeast Houston, comprising one of the lowest median household incomes in the region.

CONCLUSIONS

Toxocariasis is a devastating zoonotic infection in children living in the US. As it is not a reportable disease, the true burden remains unknown. It is critical to increase awareness of toxocariasis to direct public health interventions and ultimately reduce Toxocara -induced morbidity in US children.

The Relationship of Parasite Allergens to Allergic Diseases

PURPOSE OF REVIEW

Helminth infections modify the natural history of allergic diseases, by either decreasing or increasing their symptoms. Several helminth components are involved in the increasing of the allergic response and symptoms, overcoming the concomitant immunosuppression of helminthiases. However, the role of individual IgE-binding molecules in this process remains to be defined.

RECENT FINDINGS

We updated the list of helminth allergens and IgE-binding molecules, their effects on asthma presentation, and their impact on allergy diagnosis. Data from genetic and epigenetic studies of ascariasis are analyzed. A new species-specific A. lumbricoides allergen has been discovered, with potential use in molecular diagnosis. Most helminth IgE-binding components are not officially classified as allergens in the WHO/IUIS database, although there is evidence of their influence increasing allergic manifestations. Further immunological characterization of these components is needed to better understand their mechanisms of action and evaluate the ways in which they can influence the diagnosis of allergy.

Seroprevalence of human toxocariasis in Latin America and the Caribbean: a systematic review and meta-analysis

Introduction

The current study aimed to quantitatively synthesize available evidence regarding the seroprevalence of human toxocariasis in Latin America and the Caribbean.

Methods

A systematic research involving six electronic databases was conducted using a research strategy that combined MeSH terms with free terms. Article selection and information extraction were performed using a double and independent approach. The Newcastle-Ottawa tool was used to assess the risk of bias in the included articles. The meta-analysis used the random-effects approach, with subgroup analysis and sensitivity analysis for risk of bias also being performed.

Results

We included 101 articles with a total of 31,123 participants. The studies were conducted between 1990 and 2022, with Brazil accounting for the largest number of studies (n = 37). The overall seroprevalence of human toxocariasis was 31.0% (95% CI: 27.0-35.0%, I2 = 99%). The prevalence of the main characteristics observed in seropositive patients were as follows: ocular toxocariasis (30.0%), asymptomatic (26.0%), and presence of dogs at home (68.0%). In addition, the seroprevalence was lower in studies including only adults than in those including children or both. In contrast, no differences in seroprevalences were found between studies conducted in the community and hospital.

Conclusion

The overall seroprevalence of human toxocariasis in Latin America and the Caribbean was high. Notably, our findings showed that the seroprevalence was increased among populations who kept a dog at home but was decreased in populations comprising only adults. Our findings can be used to establish epidemiological surveillance strategies for the prevention and early identification of toxocariasis.

Toxocariasis: potential association with bronchial asthma, and pneumonia among pediatric children

Toxocariasis is an underestimated geohelminthic infection which shows respiratory changes concurrent with larval migration. The purpose of the present study was to detect Toxocara seropositivity in asthmatic and pneumonic children, and in turn to evaluate its association with the children clinical manifestations, laboratory test results, and sociodemographic risk factors. A total of 50 asthmatic, 50 pneumonic children and 50 healthy controls were subjected to stool analysis by direct wet mount and concentration techniques to exclude possible cross reactivity. Blood samples were collected for complete blood count and assessment of eosinophil count. Sera were examined for anti-Toxocara IgG antibodies, and measurement of total IgE level. Anti Toxocara IgG was detected in 27.3% (41/150) of the studied children. It was significantly higher in asthmatic group compared to controls (26%. p value = 0.033) and significantly highest in pneumonia group compared to both bronchial asthma group (46%. p value = 0.030) and control group (10%. p value = 0.001). There was a significant association between anti Toxocara IgG seroprevalence and each of eosinophilia, total IgE and both combined. Anti Toxocara IgG showed significant higher percentage in asthmatic children who recorded history of soil contact and pets contact as compared to control and pneumonic groups. Toxocara IgG seropositivity was highly associated with fever, cough, wheezes and dyspnea with statistical significance. Toxocara seropositivity has to be considered as a vital associated factor for asthmatic and pneumonic children, and eventually better to be considered in differential diagnosis by pediatricians. Further studies are still needed to explore the correlation between toxocariasis and different patient categories.

Toxocarosis in humans: how much of a problem is it in the UK?

Toxocara canis (from dogs) is recognised as a potential cause of human toxocarosis, but Toxocara cati (from cats) and other species (eg, Toxascaris leonina found in foxes) are also possible causes. Most colonisation with Toxocara species does not lead to symptomatic infection in well-cared for adult animals; young and debilitated animals are at greater risk. Humans can acquire infection from infected animals, for example, via soil contaminated with faeces; however, most human infections are asymptomatic, with symptomatic infection being very rare in the UK. The risk of human infection is reduced by measures such as hand washing and responsible disposal of dog faeces. Some organisations recommend regular prophylactic treatment of pet dogs and cats. However, there are concerns that some parasiticides are contaminating the environment. As an example of a One-Health problem there is a potential conflict between the needs of animal health, human health and the health of the wider ecosystem. Also, considering that only about 5% of non-juvenile household dogs shed Toxocara eggs at a given time, it has been questioned whether it is worthwhile to invest in frequent blind treatments. British veterinary organisations have suggested less frequent treatment may be more appropriate and should be based on individual risk assessment and faecal examinations for worms rather than blanket regular prophylactic treatment, which could reduce the impact of parasiticides on the environment without greatly increasing the risks to animal or human health.

WormWatch: Park soil surveillance reveals extensive Toxocara contamination across the UK and Ireland

BACKGROUND

Toxocarosis is a globally distributed zoonotic disease, but sources of infection are not well documented over large geographical scales. To determine levels of environmental contamination, soil from 142 parks and recreational areas across the UK and Ireland was assessed for the presence of Toxocara.

METHODS

Toxocara ova (eggs) were isolated from soil samples by sieving and flotation and then enumerated. Individual eggs were isolated and imaged, and a subset was characterised by species-specific PCR and Sanger sequencing.

RESULTS

Characteristic Toxocara-type eggs were found in 86.6% of parks, with an average of 2.1 eggs per 50 g of topsoil. Representative eggs were confirmed as Toxocara canis by Sanger sequencing, with many eggs containing developed larvae, hence being viable and potentially infective. Positive samples were more common, and egg density was higher, in parks with greater perceived levels of dog fouling.

LIMITATIONS

Samples were collected at a single timepoint and with limited spatial mapping within parks. Further study is needed to discern spatiotemporal differences within parks and recreational areas.

CONCLUSION

Toxocara is widespread in soil in public parks, indicating a need for further efforts to reduce egg shedding from pet dogs. Standardised methods and large-scale surveys are required to evaluate risk factors for egg presence and the impact of interventions.

Allergic asthma manifestations in human and seropositivity to Toxocara, a soil-transmitted helminth of carnivores: A case-control study and scoping review of the literature

Asthma is a common respiratory disease affecting humans. Helminth parasites, including Toxocara species, have been implicated as predisposing factors of asthma. However, various studies present different findings on asthma-Toxocara association. Herein, we investigated the association of asthma manifestations with Toxocara seropositivity in a case-control setting on 248 participants (147 women and 101 men), with 124 healthy individuals as the control group and 124 patients known to have asthma based on the medical records of asthma clinics of Kerman University of Medical Sciences. Consequently, we presented a scoping review of all previous studies carried out on this topic, summarizing current findings and existing knowledge on this issue. Of 248 participants, 31 (12.5%) were Toxocara-seropositive, of which 19 (15.3%) were in the patient group and 12 (9.7%) in the control group. A significant relationship was found between asthma severity and age in Toxocara-seropositive individuals (P < 0.04). We found no significant relationship between asthma and Toxocara seropositivity. We identified 7,724 related records in three major scientific databases, NCBI PubMed, Scopus, and Google Scholar. The review of the literature showed that there are 80 published articles on asthma-Toxocara relationship with contradictory findings. More than half of the studies were performed in only four countries, namely, Brazil, the Netherlands, the United States, and Iran. The study population in 70% of the studies were children, and few studies investigated asthma-Toxocara association in adults. The most common study designs for investigating the association of asthma and Toxocara seropositivity were cross-sectional (35.0%), case-control (27.5%), and animal experimental (12.5%) studies. This study found no significant relationship between asthma manifestations and toxocariasis in a case-control setting. However, a scoping review of the current literature suggests that further experimental and field longitudinal cohort studies are required to elucidate the nature of asthma-Toxocara interaction in humans.

The non-glycosylated protein of Toxocara canis MUC-1 interacts with proteins of murine macrophages

Toxocariasis is a neglected parasitic disease caused predominantly by larvae of Toxocara canis. While this zoonotic disease is of major importance in humans and canids, it can also affect a range of other mammalian hosts. It is known that mucins secreted by larvae play key roles in immune recognition and evasion, but very little is understood about the molecular interactions between host cells and T. canis. Here, using an integrative approach (affinity pull-down, mass spectrometry, co-immunoprecipitation and bioinformatics), we identified 219 proteins expressed by a murine macrophage cell line (RAW264.7) that interact with prokaryotically-expressed recombinant protein (rTc-MUC-1) representing the mucin Tc-MUC-1 present in the surface coat of infective larvae of T. canis. Protein-protein interactions between rTc-MUC-1 and an actin binding protein CFL1 as well as the fatty acid binding protein FABP5 of RAW264.7 macrophages were also demonstrated in a human embryonic kidney cell line (HEK 293T). By combing predicted structural information on the protein-protein interaction and functional knowledge of the related protein association networks, we inferred roles for Tc-MUC-1 protein in the regulation of actin cytoskeletal remodelling, and the migration and phagosome formation of macrophage cells. These molecular interactions now require verification in vivo. The experimental approach taken here should be readily applicable to comparative studies of other ascaridoid nematodes (e.g. T. cati, Anisakis simplex, Ascaris suum and Baylisascaris procyonis) whose larvae undergo tissue migration in accidental hosts, including humans.

Toxocariasis is a neglected parasitic disease of humans caused mainly by larvae of Toxocara canis. Given that T. canis is zoonotic and can infect a range of mammals, there has been substantial interest in host-parasite relationships, with studies showing that T. canis larvae secrete abundant mucins that effect/modulate immune responses and disease pathogenesis. To improve the understanding of immunomolecular interactions, we investigated the role(s) of the protein component of a mucin (Tc-MUC-1) secreted by infective larvae using a well-defined murine macrophage line (RAW264.7). The non-glycosylated recombinant protein of Tc-MUC-1 (designated rTc-MUC-1) was shown to interact with at least 219 proteins of RAW264.7 cells, particularly with the actin binding protein (CFL1) and a fatty acid binding protein (FABP5), which are involved in cell migration and phagocytosis, respectively. Based on these findings, we propose that Tc-MUC-1 regulates cytoskeletal organisation and signal transduction in host macrophages. It would be interesting to establish, using the integrative experimental approach employed here, whether the role(s) of Tc-MUC-1 protein homologues of related ascaridoids are conserved.

The role of helminths in the development of non-communicable diseases

Non-communicable diseases (NCDs) like cardiovascular disease, chronic respiratory diseases, cancers, diabetes, and neuropsychiatric diseases cause significant global morbidity and mortality which disproportionately affect those living in low resource regions including low- and middle-income countries (LMICs). In order to reduce NCD morbidity and mortality in LMIC it is imperative to understand risk factors associated with the development of NCDs. Certain infections are known risk factors for many NCDs. Several parasitic helminth infections, which occur most commonly in LMICs, have been identified as potential drivers of NCDs in parasite-endemic regions. Though understudied, the impact of helminth infections on the development of NCDs is likely related to helminth-specific factors, including species, developmental stage and disease burden. Mechanical and chemical damage induced by the helminth in combination with pathologic host immune responses contribute to the long-term inflammation that increases risk for NCD development. Robust studies from animal models and human clinical trials are needed to understand the immunologic mechanisms of helminth-induced NCDs. Understanding the complex connection between helminths and NCDs will aid in targeted public health programs to reduce helminth-induced NCDs and reduce the high rates of morbidity that affects millions of people living in parasite-endemic, LMICs globally.

Dog and Cat Contact as Risk Factor for Human Toxocariasis: Systematic Review and Meta-Analysis

Toxocariasis, a neglected parasitic zoonosis with worldwide distribution, has been reportedly associated to different risk factors in several epidemiological and meta-analysis studies. However, dog and cat contact (environmental and animal exposure) as isolated associated risk factor for children and adults remains to be fully established. Accordingly, the present meta-analysis has aimed to directly assess dog and cat contact for toxocariasis seropositivity in under-18 and adult persons, using a survey strategy of PubMed/Medline, Embase, Scopus and Scielo Databases, from January 2009 to December 2021. A meta-analysis model of random effects was applied to estimate odds ratio (OR) with 95% Confidence Interval (CI). The statistical heterogeneity was evaluated by the Cochran Q-Test and I² values. A total of 41 transversal studies (n = 20.515 individuals) from different geographic regions (classified by the World Health Organization) were included herein. In overall, 1,882/13,496 (13.95%; 95% IC = 13.4–14.5) youngers and 513/7.019 (7.3%; 95% CI = 6.7–7.9) adults in contact with dogs or cats were serologically reagent for anti-Toxocara antibodies. Association of dog and cat contact was observed only in youngers, with both dogs (OR = 1.53; p < 0.0001) and cats (OR = 1.64; p = 0.0001). In addition, association of dog and contact and serology was statistically significant in populations of Americas (OR = 1.37; 95% CI = 1.1–1.7), Middle East (OR = 2.9; 95% CI = 1.6–5.1) and West Pacific (OR = 1.6; 95% IC = 1.3–1.9). In conclusion, contact with dogs and cats, particularly by younger individuals and in regions such as Americas, Middle East, and West Pacific, should be always a public health concern for toxocariasis. Moreover, dogs and cats should be periodically dewormed, washed and hair cleaned prior to contact with youngers. Finally, robust statistical results herein may serve as basis for future strategies and preventive measures for safer dog and cat contact.

Prevalence of Toxocara Eggs in Public Parks in the City of Valencia (Eastern Spain)

Toxocara spp. is one of the most common zoonotic geohelminths in the world. Its infections are associated with the accidental ingestion of contaminated soil and affecting, especially children. In this study, feces, and soil samples from 14 public parks in the city of Valencia were analyzed. The Telemann method and a modified version of a sieving technique were used to process feces and soil, respectively. None of the fecal samples and 10.9% of soil samples from five parks (35.7%) tested positive for the presence of Toxocara eggs. The most contaminated areas were the canine sanitary parks (30.8% of the samples), followed by socialization areas for dogs (9.7%); no positive samples were found at children’s playgrounds. Our results suggest that most pets in Valencia are periodically dewormed, although additional preventive measures should be applied, since the risk of infection exists probably due to the presence of stray dogs and feral cats.

Helminth infections and allergic diseases: systematic review and meta-analysis of the global literature

INTRODUCTION

There is considerable research interest in the role of helminth infections in the development of allergic diseases. However, findings from previous studies are mixed. Existing systematic reviews of these studies are outdated. We performed a systematic review of the global literature on the association between helminth infections and development and clinical outcomes of allergic diseases.

METHODS

We searched Cochrane Library, MEDLINE, EMBASE, ISI Web of Science, PubMed, Global Index Medicus, Scielo, KoreaMed, Google Scholar, and Lilacs for studies published up to January 2020. We included observational epidemiological studies (cohort, case-control and cross-sectional studies) of children and adults reporting associations between helminth infections and asthma, allergic rhinitis, eczema and atopy. We performed random-effects meta-analysis to summarize the effect estimates.

RESULTS

We included 80 studies with 99,967 participants. In the meta-analyses, we did not observe an overall association between helminth infections and allergic diseases. There was, however, evidence that A. lumbricoides infections was associated with an increased risk of bronchial hyperreactivity in children (RR:1.41, 95%CI: 1.17-1.70; I²=50, p for I²=0.09), and was associated with an increased risk of atopy among helminth-infected adults (RR:1.37, 95%CI: 1.18-1.61; I²=52, p for I²=0.02). We found no study that addressed the association between helminth infection and clinical outcomes of allergic diseases. The overall strength of the underlying evidence was low to moderate.

CONCLUSION

Helminth infections may increase the risk of bronchial hyperreactivity in children and atopy in adults. Well-designed longitudinal cohorts may help clarify potential causal associations between chronic helminth infections and allergic diseases.

Toxocariasis-associated urinary system diseases: a systematic review of reported cases

BACKGROUND

Toxocariasis is a neglected tropical disease caused by Toxocara canis and Toxocara cati. Toxocara species can involve many organs, such as the brain, heart and lungs, however, the urinary system involvement of toxocariasis is largely unknown.

METHODS

We performed a systematic review to identify cases infected with urinary tract toxocariasis.

RESULTS

We identified seven cases that were eligible to be reviewed. Among the included citations, four studies reported bladder involvement and three reported kidney involvement. Fever, urinary, and abdominal presentations were amongst the most important clinical symptoms. Eosinophilic cystitis and nephrotic syndrome were the most common diagnoses.. The treatment regimen included a combination of anthelmintic drugs and steroids.

CONCLUSIONS

In cases of urinary tract presentations accompanied by eosinophilia or histopathologic findings suggestive of parasitic infection, toxocariasis should be included in the list of differential diagnoses, especially in endemic areas.

Identification of Toxocara canis Antigen-Interacting Partners by Yeast Two-Hybrid Assay and a Putative Mechanism of These Host-Parasite Interactions

Toxocara canis is a zoonotic roundworm that infects humans and dogs all over the world. Upon infection, larvae migrate to various tissues leading to different clinical syndromes. The host–parasite interactions underlying the process of infection remain poorly understood. Here, we describe the application of a yeast two-hybrid assay to screen a human cDNA library and analyse the interactome of T. canis larval molecules. Our data identifies 16 human proteins that putatively interact with the parasite. These molecules were associated with major biological processes, such as protein processing, transport, cellular component organisation, immune response and cell signalling. Some of these identified interactions are associated with the development of a Th2 response, neutrophil activity and signalling in immune cells. Other interactions may be linked to neurodegenerative processes observed during neurotoxocariasis, and some are associated with lung pathology found in infected hosts. Our results should open new areas of research and provide further data to enable a better understanding of this complex and underestimated disease.

Seroprevalence and associated risk factors of toxocariasis among nomads in Boyer-Ahmad County, southwest Iran

BACKGROUND

Human toxocariasis is caused by the larval stage of Toxocara canis and Toxocara cati. This cross-sectional study was conducted to evaluate the seroprevalence and the risk factors associated with Toxocara infection in nomads of Boyer-Ahmad County in the southwest of Iran.

METHODS

A total of 968 blood samples were collected from nomads. A structured questionnaire, containing sociodemographic data, was completed for each participant. Sera were evaluated for anti-Toxocara antibodies, using the T. canis excretory-secretory antigens prepared from the second stage larvae, in an ELISA system.

RESULTS

Among the 968 participants, 220 (22.7%) were males and 748 (77.3%) were females; the mean age was 40.71 y. Anti-Toxocara IgG antibodies were detected in 14 (1.4%) of the 968 nomads. The association between Toxocara infection and gender, age, contact with dogs, residential area and level of education were not statistically significant (p>0.05).

CONCLUSIONS

The findings of the study revealed a low prevalence rate of toxocariasis in nomadic communities in southwest Iran. Geographic location and climatic conditions as well as the lifestyle and sociodemographic features of the participants may contribute to the low prevalence rate of Toxocara infection.

The Role of Nile Tilapia (Oreochromis niloticus) in the Life Cycle of Toxocara spp

The present study aimed to experimentally assess Nile tilapia as potential paratenic host of Toxocara spp. A total of 15 Nile tilapia (Oreochromis niloticus) were fed with 300 embryonated Toxocara canis eggs by oral gavage, while five others of the control group received distilled water. The fish were individually analyzed at 16, 24, 48, 72, and 240 h after inoculation. Water contamination was assessed, and tissue migration by liver, gastrointestinal tract (GIT), eyes, and central nervous system. A murine model was used as the paratenic host for egg infectivity assessment. Eggs and larvae were found in plastic tank water and fish GIT, ranging from 23 to 86% per fish. Eggs and larvae were recovered from the tank water (76.3%) and fish GIT (23.7%). The counting of eggs and larvae observed was negatively correlated with number of eggs and larvae in the water tank (rho = -0.698, p = 0.003). Shedding of embryonated eggs was first detected at 16 and up to 240 h, with significant egg and larvae yield decrease on water-shedding (p = 0.001) and in the GIT (p = 0.007). Although no T. canis larva was recovered in fish tissues, egg infectivity after fish GIT transit was experimentally confirmed by mice assessment. In conclusion, despite shedding viable embryonated eggs through the gastrointestinal tract, tilapias may not play a role as a suitable paratenic hosts for Toxocara spp., posing low risk of zoonotic transmission by fish meat consumption.

Detection of antigens and anti-Toxocara canis antibodies in children with different asthma severities

INTRODUCTION

Toxocara canis can produce or exacerbate asthma, and the detection of anti-T. canis immunoglobulin G (IgG) does not discriminate between recent infection or active larva migrans. In this study, we searched for T. canis third-stage larval antigens (L3 TES) and anti-T. canis antibodies in children with different severities of asthma, controlled or uncontrolled.

METHODS

A total of 145 patients with asthma who were previously diagnosed using the Global Initiative for Asthma guidelines were included. The asthma control was evaluated with the Asthma Control Questionnaire (ACQ). Enzyme-linked immunosorbent assay was performed for the detection of L3 TES; IgG was detected using sera preadsorbed with Ascaris antigens (native kit), and a commercial kit (IgG) was used as the gold standard.

RESULTS

L3 TES was found in 2 patients (1.37%). One had L3 TES and anti-T. canis IgG, suggesting active larva migrans. In the other patient, only L3 TES was detected, likely because an infection had begun. The seroprevalence with the commercial kit and native kit was 6.2% and 17.93%, respectively. There was no significant association among asthma severity, ACQ and T. canis seroprevalence (p > .05).

CONCLUSION

It is possible to detect L3 TES in patients with asthma. Two complementary techniques that can determine the infection status with T. canis and rule out cross-reactions involve the detection of L3 TES and IgG using sera preadsorbed with Ascaris antigen. There was no significant association among asthma severity, ACQ and T. canis seroprevalence.

Mycoplasma pneumoniae infection and risk of childhood asthma: A systematic review and meta-analysis

The etiology of childhood asthma is multifactorial, atypical bacterial pathogens, including Mycoplasma pneumoniae, have been proposed as possible risk factors or contributors. This review aims to assess the possible association between M. pneumoniae infection and childhood asthma. We searched major international literature databases (up to January 10, 2021) to identify relevant studies. We used a random-effects meta-analysis (REM) model to generate the pooled odds ratio (OR) and 95% confidence intervals (CIs). Several subgroups analyses were performed concerning the IgG, IgM, and DNA detection of M. pneumoniae infection. We included 22 eligible studies; these studies involved a total of 5064 children. We found that there was a statistically significant association between M. pneumoniae infection, as determined by IgM serology (OR, 3.13; 95% CI, 1.78-5.48), and DNA detection (OR, 1.57; 95% CI, 1.25-1.97) with increased risk of any type of childhood asthma. Moreover, children with acute asthma had significantly higher seropositivity for anti- M. pneumoniae IgM antibodies (OR, 4.43; 95% CI, 2.80-7.02) than children with stable asthma. Although our findings indicate a positive association between M. pneumoniae infection and childhood asthma, well-designed and -controlled studies are need in the future to rigorously test this association and identify the underlying mechanisms.

Systematic review and meta-analysis on the risk potential of zoonotic toxocariasis from soil contamination of public places in India

Parasitic zoonoses despite of their potential threats to human health remain neglected especially in developing countries. Toxocara canis and Toxocara cati worms are considered important zoonotic parasites and the ability of their infective ova to sustain longer in suitable edaphic environments poses constant risk of infection to humans. This systematic review and meta-analysis aims to highlight the burden and importance of soil borne toxocariasis in India. A total of 14 primary prevalence studies spanned over a period from 1985 to 2017 were included in this study. Due to expected variation between studies, a random-effects model was applied by using MetaXL add-on. The apparent prevalence based on the soil samples tested positive was found in the range of 2.11 to 31.0% while the weighted pooled prevalence was estimated as 11.26 (95% CI 07.59 - 15.54%). A high heterogeneity between studies (I² = 93.39 and Q = 227.024, p = 0.00) confirmed the diversity of the populations under study. This meta-analysis highlights the need of more studies on soil transmission of zoonotic toxocariasis in India.

Seroprevalence, risk factors, and clinical symptoms of Toxocara spp. infection among children 3-15 years old in northern Iran

The World Health Organization has categorized toxocarosis as a neglected tropical disease despite its significant impact on high-risk groups such as children. This study aimed to investigate the seroprevalence, risk factors, and clinical symptoms of Toxocara spp. infection among children 3-15 years old in northern Iran. A total of 386 children were enrolled in the study. All serum samples were tested for the presence of IgG antibodies against Toxocara spp. infection using an enzyme-linked immunosorbent assay. Moreover, relevant risk factors and clinical symptom data were obtained using questionnaires. Data analysis was performed using the SPSS software version 24. The overall seroprevalence of Toxocara spp. infection was found 2.85 % (11/386). However, Toxocara spp. infection was high for some risk factors, including eating soil (14.3 %), contacting cats (6.7 %), and consuming raw vegetables (3.7 %). However, there were no statistically significant differences regarding the risk factors and socio-demographic characteristics. Considering the clinical symptoms, Toxocara spp. infection was different in children with eosinophilia (20 %), ocular disorders (8.3 %), skin disorders (7.7 %), liver disorders (4.5 %), and stomach ache (4.2 %), although not statistically significant. The results revealed that the seroprevalence of Toxocara spp. infection was relatively low in children in northern Iran. It is suggested to conduct more studies in different parts of Iran to gain a deeper understanding of the toxocarosis seroprevalence and its status in high-risk groups such as children with asthma, hypereosinophilic syndrome, allergic skin disorders, and epilepsy.

Role of cats in human toxocarosis

Toxocara cati, the feline ascarid, is ubiquitous in domestic cats globally and is increasingly recognised as an important zoonotic species. In the definitive host, infections with the adult ascarid usually do not present any clinical signs; if clinical signs do appear, it is usually in kittens infected with T. cati, especially by the transmammary route. Diseases may include cachexia, a pot-bellied appearance, respiratory disorders, diarrhoea, vomiting, among other signs, and these may present as early as 3 weeks of age. However, infections with Toxocara spp. larvae in paratenic hosts (including humans and many other animals), can result in serious complications from the migration of larvae. Historically, there has been an assumption that Toxocara canis was the most likely cause of Toxocara spp.-related disease; while it is probably true that T. canis is responsible for the majority of infections, it is important that those caused by T. cati are accurately identified so that the contribution of this parasite to human disease can be established and then handled appropriately. Overall, the detection of infections in cats and the control of parasite stages in the environment are essential to minimise the infection risk to other animals or humans.

Seroprevalence of Toxocara spp. in children (3-13 years old) in Zahedan, Southeast of Iran

Child Toxocariasis (CT) is one of the most important helminthic parasitic diseases in Iran. The current study was aimed to determine the seroprevalence of toxocariasis in children in Zahedan, southeast of Iran. In this cross-sectional study, serum samples of 373 children aged 3-13 years old referred to health centers in Zahedan were collected randomly with criteria based on the parameters that were used in earlier studies and examined for anti-Toxocara antibody using a commercial ELISA kit. Of the 373 recruited subjects, 206 (55.2%) were male and 167 (44.8%) were female. Most of the subjects (36.5%) were in the age group 3-4 years old. Anti-Toxocara antibodies were detected in the sera of five out of 373 individuals, corresponding to a seroprevalence rate of 1.3%. A significant correlation was found between the incidence of disease and eosinophilia, a history of contact with dogs or cats, as well as the consumption of raw vegetables and drinking of contaminated water. There was no significant correlation between prevalence and gender or age. The finding of this study revealed that the prevalent CT is relatively low in Zahedan region. The rate of CT infection in the southeast of Iran was lower than the rate in other parts of Iran.

Evidence for Asthma in the Lungs of Mice Inoculated with Different Doses of Toxocara canis

Toxocara canis, a common roundworm that mainly causes toxocariasis, is a zoonotic parasite found worldwide. Humans, an accidental host, can acquire T. canis infection through accidental ingestion of T. canis-embryonated egg-contaminated food, water, and soil, and by encapsulated larvae in a paratenic host's viscera or meat. Long-term residence of T. canis larvae in a paratenic host's lungs may induce pulmonary inflammation that contributes to lung injury, airway inflammatory hyperresponsiveness, and collagen deposition in mice and clinical patients. This study intended to investigate the relationship between T. canis infection and allergic asthma in BALB/c mice inoculated with high, moderate, and low doses of T. canis eggs for a 13-week investigation. The airway hyperresponsiveness (AHR) to methacholine, collagen deposition, cytokine levels, and pathological changes in lung tissues was assessed in infected mice at weeks 1, 5, and 13 postinfection. The cell composition in bronchoalveolar lavage fluid of infected mice was assessed at weeks 5 and 13 postinfection. Compared with uninfected control mice, all groups of T. canis-infected mice exhibited significant AHR, a dose-dependent increase in eosinophilic infiltration leading to multifocal interstitial and alveolar inflammation with abundant mucus secretion, and collagen deposition in which the lesion size increased with the infective dose. Infected mice groups also showed significant expressions of eotaxin and type 2 T-helper-dominant cytokines such as interleukin (IL)-4, IL-5, and IL-13. Overall, these results suggest that T. canis larval invasion of the lungs may potentially cause pulmonary inflammatory injury and could subsequently contribute to the development of allergic manifestations such as asthma.

Exposure to Toxocara spp. and Ascaris lumbricoides infections and risk of allergic rhinitis in children

Background

Substantial experimental studies suggest a role for helminthes infections in the pathogenesis of allergies, but epidemiologic data have been inconsistent. Unlike to asthma, the association between helminthes infection and allergic rhinitis (AR) has been poorly studied. Therefore, we sought to evaluate the association between exposure to Ascaris and Toxocara infections and AR.

Methods

We did an age- and gender-matched case–control study of 81 children with physician-confirmed AR and 101 control subjects in a referral hospital for pediatric diseases in northern Iran. Exposure to Ascaris and Toxocara infections was evaluated by anti-A. lumbricoides- and anti-Toxocara- IgG antibodies using a commercial enzyme-linked immunosorbent assay. Associations were determined using multivariate logistic regression.

Results

Ascaris seropositivity was higher in children with rhinitis than in controls (12.34 vs. 3.96%). Ascaris seropositivity was positively associated with AR in univariate analysis (OR, 3.42; 95% CI 1.03–11.3; P value = 0.035), but this association was not significant after adjustment for potential confounders (OR, 1.85; 95% CI 0.42–8.18). Also Toxocara seropositivity was higher in children with AR than in healthy subjects (3.7% vs. 0.99), indicating non-significant association with AR in both univariate (OR, 3.84; 95% CI 0.39–37.7) and multivariate analyses (OR, 0.8; 95% CI 0.04–15.44).

Conclusion

Our results revealed that AR is not associated with seropositivity to Ascaris and Toxocara infections in general; however, a higher seropositivity rate was found for both parasites in children with AR. More studies with longitudinal design and larger sample size are needed to elucidate this association.

Prevalence of toxocariasis and its related risk factors in humans, dogs and cats in northeastern Iran: a population-based study

BACKGROUND

Toxocariasis is one of the most common zoonotic infections in dogs and cats. The objectives of this study were to determine the prevalence of anti-Toxocara antibodies and identify the epidemiological and clinical features and related risk factors of toxocariasis in the general population along with the prevalence of this infection in dogs and cats in northeast Iran.

METHODS

In this cross-sectional study, anti-Toxocara antibodies from 1150 urban and rural participants were examined using a commercial enzyme-linked immunosorbent assay. In addition, the stool specimens of 538 dogs and 236 cats were tested using the formalin-ether concentration technique. Sociodemographic data and related risk factors were collected using a structured questionnaire and the data on clinical manifestations were obtained from personal health records.

RESULTS

Anti-Toxocara antibodies were detected in 7.2% (83/1150) of the study population. Risk factors for seropositivity based on multivariable analysis were younger age (p=0.019), living in rural areas (p=0.048), occupations with high exposure risk to toxocariasis (p=0.001), contact with dogs or cats (p=0.003), contact with soil (p=0.001), history of geophagy (p=0.001) and the consumption of raw or undercooked liver (p=0.001). The prevalence of symptoms such as asthma, shortness of breath, blurred vision, abdominal pain and epilepsy were significantly higher in seropositive individuals compared with seronegative ones. Toxocara eggs were found in 15.1% (81/538) of dogs and 34.7% (82/236) of cats. A significant relationship was found between infection in dogs and cats and age, type, place of residence and anthelmintic consumption.

CONCLUSIONS

Identification of anti-Toxocara antibodies in the general population and the presence of confirmed infections in dogs and cats indicates exposure to Toxocara infection as a public health problem in northeast Iran.

A One Health Perspective on the Human-Companion Animal Relationship with Emphasis on Zoonotic Aspects

Over time the human-animal bond has been changed. For instance, the role of pets has changed from work animals (protecting houses, catching mice) to animals with a social function, giving companionship. Pets can be important for the physical and mental health of their owners but may also transmit zoonotic infections. The One Health initiative is a worldwide strategy for expanding collaborations in all aspects of health care for humans, animals, and the environment. However, in One Health communications the role of particularly dogs and cats is often underestimated.

OBJECTIVE

Evaluation of positive and negative One Health issues of the human-companion animal relationship with a focus on zoonotic aspects of cats and dogs in industrialized countries.

METHOD

Literature review.

RESULTS

Pets undoubtedly have a positive effect on human health, while owners are increasing aware of pet's health and welfare. The changing attitude of humans with regard to pets and their environment can also lead to negative effects such as changes in feeding practices, extreme breeding, and behavioral problems, and anthropozoonoses. For the human, there may be a higher risk of the transmission of zoonotic infections due to trends such as sleeping with pets, allowing pets to lick the face or wounds, bite accidents, keeping exotic animals, the importation of rescue dogs, and soil contact.

CONCLUSIONS

One Health issues need frequently re-evaluated as the close human-animal relationship with pet animals can totally differ compared to decennia ago. Because of the changed human-companion animal bond, recommendations regarding responsible pet-ownership, including normal hygienic practices, responsible breeding, feeding, housing, and mental and physical challenges conforming the biology of the animal are required. Education can be performed by vets and physicians as part of the One Health concept.

Helminth infections, atopy, asthma and allergic diseases: protocol for a systematic review of observational studies worldwide

INTRODUCTION

Childhood infections, particularly those caused by helminths are considered to be important environmental exposures influencing the development of allergic diseases. However, epidemiological studies focusing on the relationship between helminth infections and risk of allergic diseases, performed worldwide, show inconsistent findings. Previous systematic reviews of observational studies published 10 or more years ago showed conflicting findings for effects of helminths on allergic diseases. Over the past 10 years there has been growing literature addressing this research area and these need to be considered in order to appreciate the most contemporary evidence. The objective of the current systematic review will be to provide an up-to-date synthesis of findings of observational studies investigating the influence of helminth infections on atopy, and allergic diseases.

METHODS AND ANALYSIS

This systematic review protocol was registered at PROSPERO. We will search Cochrane Library, MEDLINE, EMBASE, CINAHL, AMED, ISI Web of Science, WHO Global Health Library, Scielo, IndMed, PakMediNet, KoreaMed, Ichushi for published studies from 1970 to January 2020. Bibliographies of all eligible studies will be reviewed to identify additional studies. Unpublished and ongoing research will also be searched in key databases. There will be no language or geographical restrictions regarding publications. Critical Appraisal Skills Programme quality assessment tool will be used to appraise methodological quality of included studies. A descriptive summary with data tables will be constructed, and if adequate, meta-analysis using random-effects will be performed. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses checklist will be followed for reporting of the systematic review.

ETHICS AND DISSEMINATION

Since this systematic review will be only based on published and retrievable literature, no ethics approval will be sought. The multidisciplinary team performing this systematic review will participate in relevant dissemination activities. Findings will be presented at scientific meetings and publish the systematic review in international, peer-reviewed, open-access journals.

PROSPERO REGISTRATION NUMBER

CRD42020167249.

Human toxocariasis and atopy

To assess the possible influence of atopy on the clinical picture of human toxocariasis, a retrospective study was carried out using file records for patients who attended the Outpatient Clinic of Parasitology in Toulouse University Hospitals. A total of 106 file records for patients who had been diagnosed with common/covert toxocariasis were extracted from the database. Forty-nine patients (20 females and 29 males) were considered atopic since they exhibited a long (≥ 1 year) history of various allergic issues along with a titer ≥ 0.7 kIU/L for specific IgE against at least two out of nine mixes of common inhalant allergens. Fifty-seven patients (42 females and 15 males) were designated nonatopic on the basis of a negative result (<0.35 kIU/L) of the test for specific IgE. Demographic (age and sex), clinical (20 signs or symptoms) and laboratory (blood eosinophil count, eosinophil cationic protein, serum total IgE, and specific anti-Toxocara IgE) variables were investigated by bivariate analysis followed by multivariate regression analysis using "atopy" as the outcome variable. On the basis of our results, the clinical or laboratory picture of toxocaral disease was not affected by the presence of an atopic status.

Global and regional seroprevalence estimates for human toxocariasis: A call for action

Human toxocariasis is a parasitic disease transmitted usually from dogs and/or cats that are infected with Toxocara species, and can be associated with a range of allergic, neurological and/or visual disorders. Recent epidemiological research has estimated that ~1.4 billion people worldwide, particularly in subtropical and tropical regions, are infected with, or exposed to Toxocara species, indicating that human toxocariasis is a neglected tropical disease. Here, we review recent research efforts, consider risk factors, discuss limitations in current seroprevalence estimates, and propose some future research directions towards improved awareness, surveillance, prevention and control of this neglected disease.

Global prevalence of Toxocara infection in cats

Zoonotic parasites, including Toxocara species, of pet and stray cats are of public health importance. Justification for, and the design and implementation of prevention and control of human toxocariasis may benefit from an understanding of the zoonotic potential and prevalence of parasites in this definitive host species. This is the first systematic review and meta-analysis of cross-sectional studies, conducted to estimate the prevalence of Toxocara infection(s) in cats by geographical location, type (rural vs urban and stray vs pet), gender and age. Pooled data were assessed using a random effects-model as well as several meta-regression and stratified analyses conducted. Of 1733 peer-reviewed articles, 143 were included in this review and represented 2,158,069 cats from 51 countries. The global pooled (95% CI) prevalence of Toxocara infection in cats was 17.0% (16.1-17.8%), being highest in African (43.3%, 28.3-58.4%) and lowest in South American (12.6%, 8.2-17.0%) countries. In other WHO regions, prevalence rates of Toxocara were as follows: Eastern Mediterranean (21.6%, 15.1-28.1%), North America (18.3%, 15.4-21.2%), Europe (17.8%, 15.9-19.7%), Western Pacific (17.3%, 14.7-19.9%), and South-East Asia (14.9%, 9.8-20.1%). Prevalence of Toxocara was higher in low-income tropical countries and also in stray (28.6%, 25.1-32.1%) and young (≤12 months of age) (27.7%, 23.4-32.0%) cats than in pet (11.6%, 10.7-12.5%) and older cats (>12 months of age) (23.8%, 14.8-32.7%). This review indicates that ~118-150 million cats worldwide serve as definitive hosts of Toxocara, shedding eggs and thus contributing to the public health risk of human infection. Prevention and control of this zoonosis in cats should receive greater attention by health officials and cat owners, particularly in countries where risk factors and prevalence are highest.

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 Toxocara infection in dogs

Dogs serve as the most important definitive hosts for Toxocara canis-a causative agent of human toxocariasis and one of the most widespread zoonotic helminth worldwide. The present study was undertaken to assess the global prevalence of T. canis infection in dogs. PubMed, Scopus, Web of Science, EMBASE and SciELO were searched to identify relevant studies. A random-effects model was used to estimate the overall and the subgroup-pooled prevalences across studies, and heterogeneity was assessed via the I² test. The data were categorized according to WHO-region, different types of dogs, risk factors and environmental variables. From a total of 4370 peer-reviewed publications, 229 articles that studied 13,010,004 dogs in 60 countries met the final inclusion criteria. The overall prevalence of Toxocara infection in dogs was 11.1% (95% CI, 10.6-11.7%). The estimated prevalence in the different WHO-regions ranged from 6.4% to 19.2%: Eastern Mediterranean (19.2%, 13.7-25.5%), Africa (18.5%, 13.7-23.9%), South-East Asia (11.9%, 6.8-18.2%), North America (11.1%, 10.6-11.7%), South America (10.9%, 7.6-14.6%), Europe (10.8%, 8.9-12.9%) and Western Pacific (6.4%, 3.3-10.2%). Young (<1 year of age), stray, rural and male dogs had a significantly (P<0.001) higher prevalence of infection than older, pet, urban or female dogs. The prevalence was higher in low income countries and regions at a low geographical latitude, close to the equator, characterized as having tropical climates. From this review, it is estimated that ≥100 million dogs are infected with Toxocara around the world. This highlights the need for an increased focus on implementing affordable, appropriate control programs to reduce the public health threat of toxocariasis as a zoonosis of global importance.

Is Ascaris lumbricoides a risk factor for development of asthma? A systematic review and meta-analysis

There are numerous epidemiological and experimental evidences to suggest that Ascaris lumbricoides infection is a neglected risk factor for development of asthma. For this purpose, we conducted a systematic review and meta-analysis for better understanding of this relationship. Systematic searching (PubMed, Scopus, Web of Science and Google Scholar) was done, up to September 30, 2019 to identify the relevant studies. We applied random-effects meta-analysis model to generate the overall odds ratio (OR) and 95% confidence intervals (CIs). Heterogeneity was assessed with I2 and τ2 statistic. Finally, 19 studies (totally 25 datasets), including 14 datasets with microscopic methods (1830 asthmatic patients (APs) and 3802 healthy controls (HCs)) and 11 datasets with serological methods (1543 APs and 3507 HCs) met the eligibility criteria. Considering to the serological methods, our results demonstrated that the APs had higher seroprevalence rate of A. lumbricoides (48.3% vs. 35.1%) than HCs, showing a significant association (pooled crude OR, 1.53; 95%CI, 1.07-2.18). Moreover, microscopic methods showed a higher prevalence of A. lumbricoides infection in the APs compared to the HCs (37.2% vs. 30.2%), but no significant association was found between APs and HCs (pooled crude OR, 1.19; 95%CI, 0.92-1.55). After adjustment for confounders, results showed no significant association for both serological (pooled adjusted OR, 1.43; 95%CI, 0.93-2.19) and microscopic (pooled adjusted OR, 1.05; 95%CI, 0.78-1.42) methods. Despite heterogeneous results, accurate and better quality studies are needed to determine the effect of A. lumbricoides infection on induction or exacerbation of asthma.

Toxocariasis and the clinical spectrum

Toxocara canis and T. cati are among the most widely distributed helminthic species in the world with a high zoonotic impact. Millions of people are infected^a and hundreds of thousands are suffering from toxocarosis, a disease encompassing four different entities: larva migrans visceralis (VLM) syndrome, ocular larva migrans (OLM) syndrome, covert toxocarosis (covT), common toxocarosis (comT) and neurotoxocarosis (NT). Toxocara infections in humans may remain clinically inapparent but may also induce severe diseases. This contribution gives a synoptic overview of the most important historical, clinical, diagnostic and therapeutical aspects of toxocarosis in humans.

Seroprevalence of human toxocarosis in Europe: A review and meta-analysis

Toxocarosis is distributed worldwide and represents the most prevalent zoonotic helminth infection in industrialized countries, thereby posing a substantial risk for public health. Thus, toxocarosis is one of CDC's Neglected Parasitic Infections that has been targeted for public health action. This systematic review and meta-analysis summarizes Toxocara seroprevalence in general populations from Europe, populations suspected of Toxocara infection and defined risk groups. Random-effects meta-analysis of proportions based on 41 publications resulted in an overall seroprevalence of 6.2% (95% CI: 4.7-8.3%) in the general population of Europe. Subgroup analysis according to decades (1970-2010s) revealed a significant increase in seroprevalence, with the highest value (12.4%; 95% CI: 6.5-22.3%) in the 2010s (χ²=17.87, df=4, P=0.001). There were no significant differences between pooled prevalence rates of European sub-regions (χ²=3.01, df=3, P=0.389). Furthermore, meta-analysis of seroprevalence according to age groups, based on data from 22 publications, indicated a significantly higher pooled seroprevalence of 14.9% (95% CI: 8.5-24.8%) in people more than 50 years of age than in younger age cohorts (χ²=8.33, df=2, P=0.016). Occupational groups exposed to contaminated soil and infected animals bear substantial risk for acquiring Toxocara infection. Due to the close link between animal infection and human Toxocara exposure, a "One Health" approach for the prevention of Toxocara infection in both humans and animals is required.

Seroprevalence of Toxocara spp. antibodies in humans in Africa: A review

BACKGROUND

Human toxocariasis occurs worldwide and is caused by nematodes of the species of the genus Toxocara. Infection occurs by the ingestion of eggs and is usually asymptomatic or oligosymptomatic. However, severe manifestations occur. The burden of disease and its public health impact remain ill-defined. The aim of this review was to summarize all available data on the seroprevalence of toxocariasis on the African continent and factors associated with seropositivity.

METHODS

Twenty-seven original papers published between 1991 and 2017 were identified that provided data suitable for this review. Case-control studies were included and the seroprevalence in the (healthy) control group was used as a surrogate parameter.

RESULTS

Antibodies against Toxocara spp. were found to be frequent in most populations and regions in Africa with the exception of two publications, one from the Democratic Republic of the Congo and one from Djibouti, where all participants were seronegative. The highest proportion of participants with antibodies was found on the island of La Réunion with 359 out 387 study participants being positive (92.8%). Factors associated with seropositivity were reported across studies, including-among others-older age, contact with soil via geophagia, agricultural activity or playing with soil, contact with animals, especially dogs, and low socio-economic status, defined as absence of water supply or poor housing. Three Egyptian studies found male gender to be associated with toxocariasis, whereas in La Réunion females were at increased risk.

CONCLUSIONS

Exposure to toxocariasis seems to be very frequent and common in large parts of the African continent. However, no data are available for most countries. The public health impact of human toxocariasis and the frequency of severe manifestations remain unclear.

Prevalence of Toxocara and Toxascaris infection among human and animals in Iran with meta-analysis approach

BACKGROUND

Toxocariasis is a worldwide zoonotic parasitic disease caused by species of Toxocara and Toxascaris, common in dogs and cats. Herein, a meta-analysis was contrived to assess the prevalence of Toxocara/Toxascaris in carnivore and human hosts in different regions of Iran from April 1969 to June 2019.

METHODS

The available online articles of English (PubMed, Science Direct, Scopus, and Ovid) and Persian (SID, Iran Medex, Magiran, and Iran Doc) databases and also the articles that presented in held parasitology congresses of Iran were involved.

RESULTS

The weighted prevalence of Toxocara/Toxascaris in dogs (Canis familiaris) and cats (Felis catus) was 24.2% (95% CI: 18.0-31.0%) and 32.6% (95% CI: 22.6-43.4%), respectively. Also, pooled prevalence in jackal (Canis aureus) and red fox (Vulpes vulpes) was 23.3% (95% CI: 7.7-43.2%) and 69.4% (95% CI: 60.3-77.8%), correspondingly. Weighted mean prevalence of human cases with overall 28 records was 9.3% (95% CI: 6.3-13.1%). The weighted prevalence of Toxocara canis, Toxocara cati, and Toxascaris leonina was represented as 13.8% (95% CI: 9.8-18.3%), 28.5% (95% CI: 20-37.7%) and 14.3% (95% CI: 8.1-22.0%), respectively.

CONCLUSION

Our meta-analysis results illustrate a considerable prevalence rate of Toxocara/Toxascaris, particularly in cats and dogs of northern parts of Iran. The presence of suitable animal hosts, optimum climate and close contact of humans and animals would have been the reason for higher seroprevalence rates of human cases in our region. Given the significance clinical outcomes of human Toxocara/Toxascaris, necessary measures should be taken.

Seroprevalence estimates for toxocariasis in people worldwide: A systematic review and meta-analysis

Background

Human toxocariasis is an important neglected disease. We performed a systematic review and meta-analysis study to estimate the global and regional prevalence of anti-Toxocara serum antibodies (referred to as ‘T-seroprevalence’) in human populations around the world.

Methods

We searched five international databases (PubMed, EMBASE, Web of Science, SciELO and Scopus) for seroprevalence studies published from 1 January 1980 to 15 March 2019. We used random effect models to calculate the overall T-seroprevalence (with 95% CIs) in all six WHO regions and worldwide. We also conducted subgroup and linear meta-regression analyses to evaluate the impact of socio-demographic, geographical and climatic parameters on seroprevalence.

Results

We identified 250 eligible studies (253 datasets) comprising 265,327 participants in 71 countries for inclusion in the present meta-analysis. The estimated global T-seroprevalence rate was 19.0% (95%CI, 16.6–21.4%; 62,927/265,327); seroprevalence was highest in the African region (37.7%; 25.7–50.6%) and lowest in the Eastern Mediterranean region (8.2%; 5.1–12.0%). The pooled seroprevalence for other WHO regions was 34.1% (20.2–49.4%) in the South-East Asia; 24.2% (16.0–33.5%) in the Western Pacific; 22.8% (19.7–26.0%) in the American; and 10.5% (8.5–12.8%) in the European regions. A significantly higher T-seroprevalence was associated with a lower income level; lower human development index (HDI); lower latitude; higher humidity; higher temperature; and higher precipitation (P-value < 0.001). Potential risk factors associated with seropositivity to Toxocara included male gender; living in a rural area; young age; close contact with dogs, cats or soil; consumption of raw meat; and the drinking of untreated water.

Conclusions

The present findings indicate high levels of infection with, or exposure to Toxocara spp. in many countries, which calls for increased attention to human toxocariasis and improved measures to prevent adverse health risks of this disease.

There have been many epidemiological studies on the seroprevalence of Toxocara infection or toxocariasis in humans in individual countries, but there has been no systematic review/meta-analysis to estimate the extent of Toxocara infection or exposure in human populations worldwide. By reviewing 250 studies of 265,327 people from 71 countries, we provide the first comprehensive global estimates of T-seroprevalence in humans to date. The findings indicate that almost one fifth (19%) of the world’s human population is seropositive to Toxocara. The highest seroprevalence rates were found in Africa (37.7%) and the lowest in the Eastern Mediterranean region (8.2%). Individual countries with high HDIs and high income levels usually had low T-seroprevalence rates. Our findings also showed that T-seroprevalence varies markedly among countries, according to geographical location (coordinates) and climatic features. Evidence from this study indicates that human toxocariasis is a prevalent, neglected tropical disease and potentially one of major importance to global public health. Our study emphasizes the need for governmental authorities to pay increased attention to the risks and socioeconomic impact of HT in many countries around the world, and for them to design and implement HT prevention or control programs, considering risk predictors identified here.

A Dual Role for Macrophages in Modulating Lung Tissue Damage/Repair during L2 Toxocara canis Infection

Macrophages that are classically activated (M1) through the IFN-γ/STAT1 signaling pathway have a major role in mediating inflammation during microbial and parasitic infections. In some cases, unregulated inflammation induces tissue damage. In helminth infections, alternatively activated macrophages (M2), whose activation occurs mainly via the IL-4/STAT6 pathway, have a major role in mediating protection against excessive inflammation, and has been associated with both tissue repair and parasite clearance. During the lung migratory stage of Toxocara canis, the roles of M1 and M2 macrophages in tissue repair remain unknown. To assess this, we orally infected wild-type (WT) and STAT1 and STAT6-deficient mice (STAT1^-/- and STAT6^-/-) with L2 T. canis, and evaluated the role of M1 or M2 macrophages in lung pathology. The absence of STAT1 favored an M2 activation pattern with Arg1, FIZZ1, and Ym1 expression, which resulted in parasite resistance and lung tissue repair. In contrast, the absence of STAT6 induced M1 activation and iNOS expression, which helped control parasitic infection but generated increased inflammation and lung pathology. Next, macrophages were depleted by intratracheally inoculating mice with clodronate-loaded liposomes. We found a significant reduction in alveolar macrophages that was associated with higher lung pathology in both WT and STAT1^-/- mice; in contrast, STAT6^-/- mice receiving clodronate-liposomes displayed less tissue damage, indicating critical roles of both macrophage phenotypes in lung pathology and tissue repair. Therefore, a proper balance between inflammatory and anti-inflammatory responses during T. canis infection is necessary to limit lung pathology and favor lung healing.

A systematic review and meta-analysis of canine, feline and human Toxocara infections in sub-Saharan Africa

Toxocariasis is an emerging zoonotic disease caused by Toxocara canis and T. cati. Toxocariasis and its etiological agents are of global public health importance, whose burden appears underestimated, especially in sub-Saharan Africa (SSA). The diversity in the transmission routes of these parasites contributes to disease prevalence and often hinders disease control measures. This study aimed to review the epidemiological distribution of Toxocara infections in SSA region. A systematic review and meta-analysis were performed using PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analysis). We identified 94 relevant, peer-reviewed articles, out of which, 75 articles were found eligible based on Toxocara infections in dogs, cats and humans. Overall, 27,102 samples were examined for T. canis in dogs, T. cati in cats and Toxocara serology in humans, out of which 6142 were positive for Toxocara infection: 3717 (13.7%) in dogs (faecal, 3487; necropsy, 180; hair, 50); 266 (1%) in cats (faecal, 101; necropsy, 165); and 2159 (8%) in humans (serology). Overall mean prevalences of 19% (95% confidence interval (CI): 14-23%), 9% (95% CI: 0-28%) and 36% (95% CI: 24-49%) were recorded in dogs, cats and humans, respectively. Substantial heterogeneity was observed between studies and subgroups (I2 = 99%, P < 0.01). Findings from the review showed that studies on the epidemiology of Toxocara infections in the SSA region are limited. We strongly recommend focused, collaborative and coordinated studies to determine Toxocara spp. prevalence in various hosts, including food animals and the environment, through a 'One Health' approach across SSA countries.

The relationship between Toxocara species seropositivity and allergic skin disorders: a systematic review and meta-analysis

We performed a systematic review and meta-analysis on observational studies to evaluate the possible associations between Toxocara species seropositivity and allergic skin disorders (ASDs). We searched the MEDLINE, ScienceDirect, Scopus, Web of Science and Google Scholar databases to 15 May 2018 to identify the relevant studies. We used a random effects meta-analysis model to generate the pooled odds ratio (OR) and 95% confidence intervals (CIs). Fifteen studies, including eight studies with a case-control design (735 patients and 1342 controls) and seven studies with a cross-sectional design (a total of 4804 participants, 1302 individuals with ASDs and 3502 without ASDs), were included in the meta-analysis. We found an increased risk for ASDs in individuals with Toxocara seropositivity (OR 1.75 [95% CI 1.16 to 2.64]). Subanalysis showed that Toxocara seropositivity was significantly associated with urticaria (OR 2.97 [95% CI 1.53 to 5.76]), however, it was not significantly associated with atopy (OR 1.08 [95% CI 0.55 to 2.15]) and eczema (OR 1.62 [95% CI 0.95 to 2.78]). Moreover, the pooled ORs were 2.34 (95% CI 1.32 to 4.15) and 1.27 (95% CI 0.69 to 2.35) for case-control and cross-sectional studies, respectively. The results of our study support hypotheses regarding the existence of a positive relationship between Toxocara infection and allergic disorders, although this association should be further investigated by longitudinal and mechanism studies.