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

Serosurvey of Toxocariasis and Its Association With Allergic Asthma in Children: A Case-Control Study in Southwest Iran

Evidence from multiple data sources indicates that toxocariasis might play a role in the allergic asthma in children. This case-control study investigated the connection between Toxocara seropositivity and allergic asthma. It also sought to identify the conventional risk factors associated with both asthma and Toxocara infection. In this case-control study, 200 allergic asthma children and 208 children with no history of allergic asthma were included as the healthy group. Sera samples were examined for specific anti-Toxocara IgG antibodies using a serological assay. The overall prevalence of toxocariasis was 6.9% among children. The seroprevalence of toxocariasis in asthmatic children and healthy children was 8% and 5.8%, respectively, with no significant difference (p-value = 0.373). In subgroup analyses based on sociodemographic, Toxocara infection seropositivity was significantly associated with two independent variables, including the father's occupation (p-value = 0.017) and soil contact in asthmatic children (p-value = 0.033). Our results showed a higher prevalence of Toxocara infection in asthmatic children compared to healthy controls, but this difference was not statistically significant. To gain a clearer understanding and comparison of Toxocara infection rates between asthmatic and healthy children, additional comprehensive studies with larger sample sizes and diverse detection methods using different antigenic sources are required.

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.

Deglycosylation of Excretory-Secretory Antigens of the Second-Stage Larvae of Toxocara cati Improves Its Efficacy in the Diagnosis of Human Toxocariasis

Background

Toxocariasis is an important zoonotic infection, especially in tropical areas. One of the significant challenges in the serodiagnosis of human toxocariasis is the cross-reaction of Toxocara antigens with other parasites due to their relatively similar glycan structures. Removing the glycan structure from Toxocara excretory-secretory (TES) antigens may increase the efficacy of these antigens in the diagnosis of toxocariasis. The current study aimed to assess the efficacy of deglycosylated Toxocara cati excretory-secretory (dTES) antigens for the serodiagnosis of human toxocariasis.

Methods

Toxocara ES antigens were prepared from T. cati second-stage larvae and deglycosylated using sodium hydroxide (NaOH). The TES antigens, along with the dTES antigens, were used in an ELISA as well as a western blotting system for the detection of anti-Toxocara antibodies. Sera samples collected from 30 confirmed cases of toxocariasis, 30 patients with other diseases, and 30 healthy subjects were evaluated by both systems.

Results

The sensitivity of TES and dTES ELISA for the diagnosis of human toxocariasis was 96.67% (95% CI = 82.78-99.92) and 93.33% (95% CI = 77.93-99.18), respectively, while the specificity of dTES (88.33%; 95% CI = 77.43-95.18) increased significantly compared to the TES (80.00%; 95% CI = 67.67-89.22). The sensitivity of both antigens was 100% (95% CI = 88.43-100) by the western blotting system. Moreover, the specificity of TES and dTES antigens was 95% (95% CI = 86.08-98.96) and 98.33% (95% CI = 91.06-99.96), respectively, when using the western blotting system.

Conclusion

Results of the current study indicate that the chemical removal of the glycan epitopes of T. cati ES antigens significantly reduces cross-reactivity rates with other parasitic infections. Considering the findings of the present study, the dTES antigens seem to be suitable antigens for the serodiagnosis of human toxocariasis.

Seroprevalence of Toxocariasis and Its Associated Risk Factors among Adult Population in Kavar District, Fars Province, South of Iran: A Cross-Sectional Community-Based Seroepidemiological Survey

Toxocariasis as a common neglected disease is the culprit of infecting all age groups. The current cross-sectional study was designed to assess the seroprevalence of toxocariasis and risk factors associated with seropositivity of Toxocara infection among the general population of adults in the Kavar district, south of Iran. A total of 1060 participants with an age range of 35 to 70 years from the Kavar region entered the study. Manual ELISA was utilized to detect anti-Toxocara-specific antibodies in their serum samples. In addition, demographic information as well as risk factors related to toxocariasis was collected from individuals who participated in the survey. The mean age of the participants was 48.9 (±7.9) years old. Out of 1060 subjects, 532 (50.2%) were men, and 528 (49.8%) were women. The overall Toxocara seroprevalence was 5.8% (61/1060). The prevalence of Toxocara seropositive cases was significantly different between males and females (p = 0.023). The seropositive rate for Toxocara infection was also significantly higher in housewives (p = 0.003) and subjects with learning disabilities (p = 0.008). Multivariable logistic regression revealed that housewives (OR = 2.04, 95% CI: 1.18-3.51, p = 0.010) and subjects with learning disability (OR = 3.32, 95% CI: 1.29-8.52, p = 0.013) were at increased risk of Toxocara infection. The findings of the current study depicted a noticeable seroprevalence of Toxocara infection in the general population in the Kavar district, southern Iran. An increased risk of toxocariasis has been associated with learning disabilities and being a housewife. All of the toxocariasis-positive cases had contact with animals, at some point in their life. In perspective, it is necessary to raise awareness of this infection among the population while surveilling Toxocara infection in high-risk groups.

Seroprevalence of toxocariasis among allergic patients in Kuwait and its association with eosinophilia

Toxocariasis is a worldwide helminthic infection which is transmitted from infected dogs and cats and has been associated with peripheral blood eosinophilia. The Centers for Disease Control and Prevention (CDC) placed toxocariasis among the top 6 parasitic diseases in the USA which are prioritized for public health action. To our knowledge, there are no reports on human toxocariasis in Kuwait or in the other Gulf Cooperation Council (GCC) countries. This study aims at investigating the seroprevalence of toxocariasis among allergic patients in Kuwait and its association with eosinophilia, age, gender, nationality, and history of direct contact with dogs or cats. From September to December 2021, the laboratory records of allergic patients referred to Al-Rashed Allergy Hospital, Kuwait were reviewed and a total of 400 serum samples were selected: 200 samples from patients with normal eosinophil count (< 500 cells/μl) and 200 samples from patients with eosinophilia (> 500 cells/μl). The sera were screened for anti-Toxocara canis IgG antibodies via antibody enzyme-linked immunosorbent assay (Ab-ELISA). The seropositive patients were asked about their history of direct contact with dogs or cats. Statistical analyses were performed using Microsoft Excel® Analysis ToolPak software. Toxocariasis seropositivity was detected in 10 out of 400 (2.5%) allergic patients. Five patients had eosinophilia while 5 had normal eosinophil count. There was no difference in mean age or gender between Toxocara-seropositive and seronegative patients (p > 0.05). The seroprevalence rate was lower-than-expected among Kuwaiti patients (2/307, 0.7%) in comparison with non-Kuwaiti patients (8/57, 14.0%) (χ2 = 33.603, df = 1, p < 0.001) who originated from endemic South/Southeast Asian countries. Seven out of 8 (87.5%) seropositive patients had a history of direct contact with cats, dogs, or both. The seroprevalence rate of toxocariasis among allergic patients in Kuwait was 2.5%. Raising awareness and early deworming treatment/prophylaxis for juvenile dogs and cats remain crucial for toxocariasis prevention.

High Seroprevalence of Toxocara Infection among Mentally Retarded Patients in Hormozgan Province, Southern Iran

Mentally retarded individuals are more likely to become infected with soil-transmitted infections including toxocariasis. The current study aimed to determine the serostatus of toxocariasis among institutionalized mentally retarded individuals in Hormozgan Province, in the south of Iran. Subjects of the study were 117 mentally disabled individuals, including children and adults, maintained in a charity-based institution. Three millilitres of venous blood was taken from each subject. While sampling, demographic features of the subject were documented in a questionnaire. An ELISA system based on Toxocara larvae excretory-secretory antigens (TES) was utilized to detect anti-Toxocara IgG antibodies in the sera of the patients. The mean age of the subject was 27.6 (±12.31) years and consisted of 55 (47%) males and 62 (53%) females. Out of 117 cases, 33 (28.2%) were seropositive for toxocariasis. The seroprevalence was higher in females (37.1%) than males (18.2%), and the difference was statistically significant (p < 0.05). Out of 117 subjects, 76 (64.9%) had severe and 41 (35.1%) had profound mental retardation. Anti-Toxocara antibodies were detected in 18 (23.7%) patients with severe and 15 (35.6%) patients with profound mental retardation. The highest seroprevalence rate of toxocariasis (44.4%) was observed in the age group of ≤10 years followed by 21–30 years old (36.7%). No statistically significant association was seen between the age and also the duration of residency in the care center and seropositivity of toxocariasis (p > 0.05). The current study represents the high prevalence of toxocariasis in mentally retarded patients in Hormozgan Province, southern Iran. The elevated seroprevalence rate of toxocariasis in the current study indicates that these subjects constitute a high-risk group for Toxocara infection, which may be attributed to their behavioral patterns.