Seroprevalence of Toxocara canis infection and associated risk factors among primary schoolchildren in rural Southern Thailand

Clinical and laboratory characteristics of Toxocara canis infection among children in Ho Chi Minh City, Vietnam

BACKGROUND

This study determines the clinical and paraclinical characteristics of children with Toxocara canis infection and serum eosinophil cut-off values for predicting toxocariasis in the group displaying symptoms of itching, urticaria and erythema.

METHODS

A cross-sectional study was conducted during March and April 2023 with a sample size of 986 children aged 3-15 y.

RESULTS

In total, 140 (14.2%) of the 986 participants had anti-T canis antibodies. The most frequently experienced symptoms in this group were itching (10.1%), abdominal pain (8.2%) and urticaria (3.3%). The rate of IgE increased (37%), and the rates of mild and high eosinophilia were 38% and 2.2%, respectively. There were significant differences in IgE concentration and eosinophil count, and for both IgE concentration and eosinophil count between the two groups with and without toxocariasis. The optimal threshold for eosinophil to predict toxocariasis was 0.38 K/µL, with itching, urticaria and erythema resulting in a sensitivity of 61.5%, a specificity of 82.1% and a receiver operating characteristic curve (area under the curve) of 0.71.

CONCLUSIONS

This study confirmed a positive association between IgE concentration, eosinophil count and positive serology for T. canis. A general blood count, including eosinophils, is a simple test that can be performed in hospitals. Clinicians should target and screen for T.oxocara canis infection when children display clinical symptoms of itching, urticaria, erythema and eosinophilia.

CLINICAL TRIAL REGISTRATION NUMBER

NCT05208333.

Serological diagnosis of Toxocara canis in mothers and their neonate referred to selected teaching hospitals, Tehran, Iran, 2020

Toxocariasis is a common zoonotic parasitic disease, primarily caused by the larvae of Toxocara canis or T. cati. Humans become infected through accidental ingestion of infective eggs in soil contaminated with feces of infected animals, or by consuming undercooked meat from paratenic hosts harboring Toxocara larvae. This cross-sectional study aimed to evaluate the seroprevalence of Toxocara spp. in 250 mothers and their 250 neonates referred to selected teaching hospitals affiliated with Shahid Beheshti University of Medical Sciences, Tehran, Iran in 2020. Data were recorded using a specialized questionnaire, and serum and peripheral blood smears (for eosinophil count) were collected. Serum samples were tested using the ELISA serological test for IgG antibodies against Toxocara spp. The collected data were analyzed using IBM SPSS Statistics software version 21.0. A chi-square test was performed, and a P value less than 0.05 was considered statistically significant. Among the 500 participants, 24 cases (4.8%) tested positive for anti-Toxocara canis IgG antibodies. Seropositive cases included 6 mothers only (25%), 6 neonates only (25%), and 12 cases both mother and their neonate (50%). Statistical analysis showed a significant relationship between the presence of anti-Toxocara antibodies and hospital type and nationality (P value < 0.05). However, no significant relationship was found between the presence of antibodies and other demographic variables such as age, sex, eosinophilia, and history of contact with animals in mothers and their neonates (P value > 0.05). This study indicates a substantial rate Toxocara infection in mothers and neonates, necessitating appropriate preventive measures by the relevant authorities.

Zoonotic Enteric Nematodes and Dermatophytes in Cat Cafés: An Investigation in the Bangkok Metropolitan Area, Thailand

Cat cafés have gained significant popularity worldwide, offering a unique interface between humans and cats. The present study aims to assess the prevalence of potentially zoonotic endoparasites and dermatophytes from cats living in cat cafés situated in the Bangkok metropolitan area in 2017-2018. Cat fecal samples were subjected to microscopic examination employing centrifugal flotation and centrifugal sedimentation techniques. The hair samples from every cat were cultured on a dermatophyte test medium and Sabouraud dextrose agar and subsequently confirmed by visualization of the typical colony and macroconidia morphology. Findings from 11 cat cafés indicated an 18.2% (2/11) prevalence of gastrointestinal parasites, including Toxocara spp., Ancylostoma spp., Physaloptera spp., and Eucoleus aerophilus. Dermatophytes were prevalent in 16.2% (32/198) of the total number of cats tested, with Microsporum canis being the sole species identified. Notably, the presence of dermatophyte was significantly correlated with the presence of skin lesions and the cats' origin. In summary, the findings of this study have provided evidence of potentially zoonotic endoparasites and dermatophytes in cats residing in cat cafés. Therefore, it is imperative to heighten awareness and encourage preventive measures among cat café owners and customers to halt the dissemination of these pathogens.

Ocular Brugia pahangi Filariasis Complicated by Severe Macular Damage in Thailand: Case Report and Literature Review

Extralymphatic filariasis caused by filaria of zoonotic origins has been frequently reported in Thailand over recent years. Here, we report the first case of ocular filariasis in a 7.5-year-old Thai boy who initially presented with progressive conjunctival redness and blurred vision in his right eye. A small, slender, coiled worm was found and surgically removed from the right anterior chamber. Histopathological examination illustrated predominant eosinophilic inflammation surrounding the parasite, which showed smooth and thin cuticle, prominent lateral chords, flat and broad muscle cells, one intestine, and two reproductive tubes with unsegmented ova, typically characteristic of a female adult Brugia filarial nematode. The parasite was also molecularly identified as B. pahangi, based on mitochondrial cytochrome c oxidase subunit I sequence analysis. The patient was then empirically prescribed albendazole, systemic prednisolone, and topical methylprednisolone. Unfortunately, his vision did not recover after 2 months due to severe maculopathy, most likely resulting from parasitic infestation and subsequent vitreous inflammation. To the best of our knowledge, this is the first case of ocular infestation by B. pahangi with visual complications that occurred outside a filariasis-endemic area of Thailand. Furthermore, this report provides clinical data on preceding cases of B. pahangi filariasis formally reported in southeast Asian countries, including Thailand and Malaysia, which facilitate a better understanding of the epidemiology of this sporadic zoonotic infection for effective disease elimination.

The seroprevalence of toxocariasis and related risk factors in children in Ho Chi Minh City, Vietnam: results from a school-based cross-sectional study

BACKGROUND

Children are especially vulnerable to Toxocara infection and its severe complications; however, there have not been any published data on the disease prevalence and treatment effectiveness in the population of Vietnamese children. This study was conducted to determine the prevalence of toxocariasis and explore factors associated with Toxocara infection in children aged 3-15 y in Ho Chi Minh City, Vietnam.

METHODS

We conducted a cross-sectional study using a multistage cluster sampling approach in public schools. Blood samples were collected, and toxocariasis cases were confirmed, based on a history of contact with dogs/cats and positive anti-Toxocara antibody detection via ELISA. We calculated the percentage of seropositive children across gender, grade levels, districts and caregiver education. Multiple regression models were employed to identify potential risk factors.

RESULTS

Anti-Toxocara antibodies were found in 14.2% of the 986 children studied. Significant variations in seropositivity were observed across grade levels, districts and caregiver education levels. Multivariable analysis identified caregiver education, contact with dogs/cats and improper handling of pet feces as seropositivity risk factors.

CONCLUSION

This was the first community-based prevalence study of toxocariasis in a pediatric population in Vietnam. Implementation of preventive measures such as public education, routine fecal examinations and chemotherapeutic treatment of animals is highly recommended.

Prevalence of antibodies to Toxocara canis and its associated risk factors in socio-economically deprived nomadic communities of Pakistan

Toxocariasis is an important zoonotic disease caused by Toxocara (T.) canis with considerably higher prevalence in developing countries. The data on its epidemiology, especially in socioeconomically deprived nomadic communities, are scarce in Pakistan. Therefore, this study was conducted to determine the prevalence of anti-T. canis antibodies and its associated risk factors in nomadic communities located in and around Multan, Pakistan. A total of 184 sera samples were collected from nomadic communities by simple random sampling technique. The descriptive epidemiological data of participants were collected on well-designed questionnaires. Prior consent was also obtained from the participants to use the data generated from their samples without showing their identity. All the samples were analysed for the detection of anti-T. canis antibodies using commercially available Enzyme-Linked-Immunosorbent-Assay (ELISA) kits having 91% sensitivity and 96% specificity (Bordier Affinity Products, Switzerland). The overall seroprevalence of toxocariasis among nomadic communities was 27.7% (51/184). Various factors, including age, known disease history, nutritional status, contact with dogs, practice of hand washing after contact with dogs, use of unwashed vegetables, body mass index, and drug abuse, showed significant correlation (p < 0.05) with toxocariasis in nomadic communities. Conversely, other factors, including gender, marital status, educational status, awareness about zoonotic diseases, source of drinking water, occupation, location, hand washing before taking food, exposure to soil, and hygienic eating behaviour, showed non-significant correlation (p > 0.05) with seroprevalence of toxocariasis. Results also showed that >50% of seropositive cases were asymptomatic, whereas cough and abdominal pain were recorded in 19.6% and 11.76% of seropositive cases, respectively. Keeping in view, it is suggested to conduct surveys at mass level to rule out the exact disease status at national level and to include nomadic communities in local, national, and regional disease control programs through provision of better healthcare facilities and awareness about the disease.

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.

Seroprevalence of anti-Toxocara canis antibodies and associated risk factors among dog owners in the rural community of Nakhon Si Thammarat province, southern Thailand

Background

Human toxocariasis is a zoonotic parasitic disease caused by the Toxocara canis and T. cati nematodes larvae. Dog owners are at a higher risk of acquiring T. canis infection, and there is no available evidence regarding the seroprevalence of T. canis infection among dog owners in Thailand. Therefore, this study aimed to investigate the seroprevalence of T. canis infection and associated risk factors among dog owners in rural areas of Thailand.

Methods

A total of 132 dog owners, including 25 men and 107 women, were recruited for this study. Serum anti-T. canis IgG antibodies were detected using a commercial enzyme-linked immunosorbent assay (ELISA) kit, and information on risk factors was collected using a questionnaire. In addition, hematological parameters were analyzed by the auto hematology analyzer. Risk variables associated with T. canis infection were investigated using univariate and multivariate logistic regression models.

Results

The overall seroprevalence of T. canis was 76.5% (101/132). Men were more likely to be infected with T. canis than women. Univariate analysis revealed that dog owners who did not practice handwashing before meals (p = 0.005) or after contact with soil (p = 0.035) or dogs (p = 0.049) had a substantially higher risk of acquiring T. canis infection. After adjusting for confounders, not practicing handwashing before meals remained a significant risk factor for T. canis infection (p = 0.038). The mean number of eosinophils was significantly higher in the seropositive group than in the seronegative group.

Conclusions

This is the first serological report of T. canis infection among dog owners reflecting the high rate of T. canis seropositivity in rural areas of southern Thailand. This study also provides group-specific data concerning modifiable risk behaviors for more effective T. canis infection control and prevention strategies in Thailand.

Supplementary Information

The online version contains supplementary material available at 10.1186/s41182-022-00425-4.

The Value of the Antibody Detection in the Diagnosis of Ocular Toxocariasis and the Aqueous Cytokine Profile Associated With the Condition

Introduction

To evaluate and compare the specificity of Toxocara canis-specific antibody detection in the serum and aqueous samples for the diagnosis of ocular toxocariasis (OT) and explore the cytokine profiles associated with the condition in children.

Materials and Methods

This is a prospective cohort study. The inclusion criteria were the clinical presentations of OT, which included unilateral vision reduction, typical peripheral or posterior pole granuloma with variable degrees of vitritis, and exclusion of other diagnoses. The titer of antibody against the excretory-secretory antigen of Toxocara canis [T-immunoglobulin G (IgG)] was measured in serum and aqueous samples that were taken from the affected eyes. The diagnosis of OT was made upon positive detection of T-IgG either in the serum or aqueous. The rest with typical clinical presentations as described above but a positive serum or aqueous T-IgG could not be confirmed were diagnosed as suspected OT. Cytokines were measured using multiplexed cytometric bead array system.

Results

Two hundred and eleven eyes of 211 patients had participated in the study. One hundred and twenty-eight eyes were diagnosed as OT. The median age of the cohort was 7.7 years with a male to female ratio of 2.5:1. Major initial symptoms were decreased vision (74%) and strabismus (22%). The percentages of eyes with peripheral granuloma, posterior granuloma, and endophthalmitis were 40, 18, and 41%, respectively. Vitritis (100%), vitreous strands (64%), retinal fibrotic bands (57%), and retinal detachment (42%) were the most common signs. T-IgG was positive in 66.7% of the aqueous and 57.2% of the serum samples. Forty-four patients were diagnosed T-IgG negative in both serum and aqueous of the affected eyes. Interleukin (IL)-6, monocyte chemoattractant protein (MCP)-1, IL-8, eosinophil chemotactic protein (Eotaxin), MCP-1β, and vascular endothelial growth factor (VEGF) were higher in T-IgG negative eyes when compared to controls and further increased in T-IgG positive eyes. However, only T-IgG positive eyes showed increased IL-5, IL-13, and IL-10. IL-1β, tumor necrosis factor-alpha (TNF-α), IL-12, IL-2, interferon-gamma (IFN-γ), and IL-4 were undetectable in all eyes.

Conclusions

Pediatric OT is often present with severe retinal complications. Polarized intraocular Th2 response was only found in aqueous T-IgG positive eyes. Our results supported an aqueous sample-based antibody test for the more specific diagnosis of OT.

Automated Diagnostics: Advances in the Diagnosis of Intestinal Parasitic Infections in Humans and Animals

The increasingly close proximity between people and animals is of great concern for public health, given the risk of exposure to infectious diseases transmitted through animals, which are carriers of more than 60 zoonotic agents. These diseases, which are included in the list of Neglected Tropical Diseases, cause losses in countries with tropical and subtropical climates, and in regions with temperate climates. Indeed, they affect more than a billion people around the world, a large proportion of which are infected by one or more parasitic helminths, causing annual losses of billions of dollars. Several studies are being conducted in search for differentiated, more sensitive diagnostics with fewer errors. These studies, which involve the automated examination of intestinal parasites, still face challenges that must be overcome in order to ensure the proper identification of parasites. This includes a protocol that allows for elimination of most of the debris in samples, satisfactory staining of parasite structures, and a robust image database. Our objective here is therefore to offer a critical description of the techniques currently in use for the automated diagnosis of intestinal parasites in fecal samples, as well as advances in these techniques.

Soil Contamination with Toxocara Eggs in Public Schools in Rural Areas of Southern Thailand

Soil is considered the primary source of Toxocara transmission to humans, especially children. The status of soil contamination with Toxocara eggs in southern Thailand is unknown. This study aimed at estimating the soil contamination with Toxocara eggs in public schools in Nakhon Si Thammarat province in southern Thailand. Soil samples were collected from 12 public schools between August and September 2017. At each site, ten soil samples were collected from the following five types of locations: (1) playgrounds, (2) football fields, (3) sidewalks, (4) schoolyards, and (5) areas around cafeterias. In total, 120 samples were examined for Toxocara eggs with a modified flotation method using a sucrose solution. Toxocara eggs were detected in 8 (66.7%) of the 12 studied public schools. Of the 120 soil samples, 22 (18.3%; 95% CI: 11.9, 26.4) were contaminated with Toxocara eggs. The highest levels of Toxocara egg contamination were observed in playgrounds (41.7%; 95% CI: 22.1, 63.4), followed by football fields (20.8%; 95% CI: 7.1, 42.2), sidewalks (12.5%; 95% CI: 2.7, 32.4), and schoolyards (12.5%; 95% CI: 2.7, 32.4). There were significant differences in the distribution of Toxocara eggs across location types (p < 0.05). The findings demonstrated that the soil samples from public schools were contaminated with Toxocara eggs. Playgrounds were the most heavily contaminated locations. Teaching children proper handwashing steps and discouraging geophagia should be implemented to reduce the distribution of Toxocara and limit future Toxocara infections.