An increase in peripheral blood eosinophils in helminth infections is expected, and these cells are known to promote immunity against these parasites. However, studies have suggested that in some specific helminths, eosinophils may promote the needs and longevity of these parasites, and their role in these infections remains undefined, including in Toxocara canis infection. Thus, this study aimed to investigate the role of eosinophils in the context of larval migration of T. canis and the immunopathological aspects of infection. For this, we used wild-type mice and mice genetically deficient for the transcription factor GATA-binding factor 1 (GATA1−/−), infected with 1000 eggs of T. canis. At 0, 3, 14 and 63 days post-infection, parasite load, tissue cytokine production, leucocyte profile, bronchoalveolar lavage cells and histopathological analyses were carried out. Collectively, our results demonstrate that the presence of eosinophils mediates susceptibility to T. canis, inducing leucocytosis and the formation of granulomas, increasing the pulmonary and cerebral parasite load, and reducing the number of neutrophils, which may be necessary to control the infection.

Probiotics have been shown to reduce the intensity of Toxocara canis infection in mice. However, larval transmission of this nematode also occurs via transplacental and transmammary routes. Thus, the aim of this study was to evaluate the effect of the Saccharomyces boulardii probiotic on the vertical transmission of T. canis in Swiss mice. The mice received 107S. boulardii colony-forming units per gram of food. The supplementation began 15 days before mating and was maintained throughout pregnancy and lactation. The animals were inoculated with 300 T. canis embryonated eggs on the 14th day of pregnancy. The presence of larvae was examined in the organs of the females and their offspring. The examined organs included the following: brain, liver, lungs, heart, kidneys, spleen, eye, skeletal muscle (carcass) and mammary glands of lactating females. There was a 42% (P = 0.041) reduction in the number of larvae transmitted to offspring in the group that received probiotic-supplemented food (GI). Additionally, there was a 50% reduction (P = 0.023) in the number of larvae found in the brains of lactating offspring in the GI group. These results reveal the potential of S. boulardii probiotic use as an auxiliary method of controlling visceral toxocariasis.

Toxocariasis is a zoonotic disease caused mainly by Toxocara canis and Toxocara cati and diagnosis in dogs and cats is an important tool for its control. For this reason, a new coprological loop-mediated isothermal amplification (LAMP) assay was developed for the simultaneous detection of these species. The primer set was designed on a region of the mitochondrial cox-1 gene. Amplification conditions were evaluated using a temperature gradient (52°C to 68°C), different incubation times (15–120 min), and different concentrations of malachite green dye (0.004–0.4% w/v). The analytical sensitivity was evaluated with serial dilutions of genomic DNA from T. canis and T. cati adult worms, and with serial dilutions of DNA extracted from feces using a low-cost in-house method. The specificity was evaluated using genomic DNA from Canis lupus familiaris, Felis catus, Escherichia coli, Toxascaris leonina, Ancylostoma caninum, Echinococcus granulosus sensu stricto and Taenia hydatigena. The LAMP assay applied to environmental fecal samples from an endemic area showed an analytical sensitivity of 10–100 fg of genomic DNA and 10−5 serial dilutions of DNA extracted from feces using the low-cost in-house method; with a specificity of 100%. Additionally, the total development of the assay was carried out in a basic laboratory and per-reaction reagent cost decreased by ~80%. This new, low-cost tool can help identify the most common agents of toxocariasis in endemic areas in order to manage prevention strategies without having to rely on a laboratory with sophisticated equipment.

Serological antibody detection by enzyme-linked immunosorbent assay (ELISA)- and immunoblot-based methods constitutes the best indicator of human Toxocara infection. Nevertheless, the availability of serological tests, particularly western blots (WB), evaluated for sensitivity and specificity is limited. Therefore, an Anti-Toxocara-ELISA immunoglobulin g (IgG) prototype (Proto-ELISA) and an Anti-Toxocara-Westernblot (IgG) prototype (Proto-WB) were evaluated by testing 541 human sera pre-determined for Toxocara infection by an established in-house Anti-Toxocara-ELISA (IH-ELISA). To evaluate sensitivity and specificity of the newly developed ELISA and WB prototypes, results were compared to IH-ELISA and a commercial WB (Com-WB). Compared to the IH-ELISA, a sensitivity of 93.1% (229/246) and a specificity of 94.6% (279/295) of the Proto-ELISA with a Cohen's κ of 0.88 were obtained. The sensitivity of the Proto-WB was 76.7% (240/313) and specificity was 99.6% (227/228) with a Cohen's κ of 0.73 compared to those of Com-WB. A comparison to the IH-ELISA revealed 91.5% (225/246) sensitivity and 94.6% (279/295) specificity of the Proto-WB with a Cohen's κ of 0.86. Cross-reactivity was observed for some samples positive for Ascaris and Trichinella spp. in the Proto-ELISA, Proto-WB and Com-WB. Overall, the evaluated ELISA and WB prototypes showed high sensitivity and specificity, indicating high reliability of these newly developed tests.

Toxocara canis is an important zoonotic roundworm distributed worldwide. The infective larvae of T. canis are one of the causes of visceral larva migrans (VLM), a clinical syndrome in humans. Diagnosing VLM is difficult, and the differential diagnosis of the larval development stage is limited. Therefore, this experimental research aimed to diagnose T. canis larvae using a molecular method, not only in liver tissue, which is the most commonly affected tissue, but also in the limb muscles, lungs and brain tissues. For this purpose, 24 BALB/c mice were infected with 1000 embryonated T. canis eggs. Necropsies were performed on the second, fourth, seventh and 14th days post-infection. While a part of the samples were digested with pepsin-HCl, the molecular method was used for the remainder of the samples to replicate the mitochondrial DNA adenosine triphosphate (ATP) synthase subunit-6 gene region of T. canis. BbsI, a restriction endonuclease, was used to determine the specificity of the amplicons obtained from Polymerase chain reaction (PCR). The detection limit for embryonated eggs was recorded. The PCR results showed that the sensitivity of the PCR analysis was 83.3% in the liver (with 88.8% accuracy), 87.5% in the lungs (with 91.6% accuracy) and 75.0% in the brain, forelimb and hindlimb muscles (with 83.3% accuracy). In all tissues, the test specificity was determined to be 100%. In this study, the molecular method was applied to only experimentally infected BALB/c mice tissues; thus, it is suggested that it can be also employed in different paratenic hosts and materials possibly infected with T. canis.

Toxocara canis (Werner, 1782) is a zoonotic nematode commonly parasitizing dogs worldwide with great public health importance as the aetiological agent of human toxocariasis. In this respect, the aim of this study was to evaluate the effect of six disinfectant products commonly used in kennels, veterinary clinics and as household cleaning products on the embryogenesis and viability of T. canis eggs. The composition of active ingredients in these commercial disinfectants was sodium hypochlorite (A); a mix of N-(3-aminopropyl)-N-dodecylpropan-1.3-diamine and didecyldimethylammonium chloride (B); sodium dichloroisocyanurate dehydrate (C); a mix of glutaraldehyde, quaternary ammonium compounds, benzyl-c12-18-alkyldimethyl and chlorides (D); a mix of 2-propanol, ethanol, benzalkonium chloride and glucoprotamin (E); a mix of pentapotassium bis (peroxymonosulphate) bis (sulphate), sodium C10-13-alkylbenzenesulphonate, malic acid, sulphamidic acid, sodium toluenesulphonate, dipotassium peroxodisulphate and dipentene (F). After dilution, the tested disinfectants had the maximal concentration recommended by the manufacturer in order to achieve a biocidal effect. Each product was tested on approximately 10,000 T. canis eggs, having five different contact times (5, 10, 15, 30, 60 min). Three replicates were tested for each diluted disinfectant and for each contact time. After the treatment, eggs were washed and incubated in distilled water at 27 °C for 2 weeks. None of the tested products had a significant inhibitory effect on the embryogenesis and viability of T. canis eggs, regardless of the contact time. Moreover, after 2 weeks, in all tested samples, eggs containing motile infective larvae were identified, showing that routinely used disinfectants do not eliminate risk of infection by T. canis.

Uveitis is one of the commonest causes of vision loss worldwide and its exact etiology is still not clarified in most patients. The current study is a trial to assess the efficacy of serum anti-Toxocara immunoglobulin G (IgG) by enzyme-linked immunosorbent assay (ELISA) as a diagnostic tool for ocular toxocariasis (OT) and to detect OT prevalence and the associated ocular manifestations in sera of patients with uveitis. One hundred and twelve patients (62 females and 50 males) with uveitis were diagnosed by ophthalmologists, radiologists and rheumatologists according to ocular manifestations, laboratory and radiological investigations. Serum anti-Toxocara IgG titers were determined by ELISA in sera of all patients. Our results revealed that OT is highly associated with intermediate and posterior uveitis. Children and young adult females, especially those residing in rural areas, complained mainly of diminution of vision in the left eye, with strabismus and leukocoria. At a cut-off value of 0.258, the sensitivity and specificity of IgG ELISA were 93.3% and 100%, respectively. In conclusion, at a novel cut-off value of 0.258 the serum anti-Toxocara IgG ELISA is predicted to be a diagnostic tool for OT regarding sensitivity and specificity. Also, it has potential importance in the interpretation and differential diagnosis of OT. Thus, serum anti-Toxocara IgG ELISA should be a routine test for screening of suspected cases.

Human toxocarosis is a chronic tissue parasitosis most often caused by Toxocara canis. The seroprevalence can reach up to 50%, especially among children and adolescents. The anthelmintics used in the treatment have moderate efficacy. The aim of this study was to evaluate the in vitro and in vivo anthelmintic activity of quinones and their derivatives against T. canis larvae and the cytotoxicity of the larvicidal compounds. The compounds were evaluated at 1 mg mL−1 concentration in microculture plates containing third stage larvae in an Roswell Park Memorial Institute (RPMI) 1640 environment, incubated at 37 °C in 5% CO2 tension for 48 h. Five naphthoxiranes were selected for the cytotoxicity analysis. The cell viability evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and lactate dehydrogenase assays using murine peritoneal macrophages isolated from C57BL/6 mice revealed that the naphthoxiranes (1 and 3) were less cytotoxic at a concentration of 0·05 mg mL−1. The efficacy of naphthoxiranes (1 and 3) was examined in murine toxocarosis also. The anthelmintic activity was examined by evaluating the number of larvae in the brain, carcass, liver, lungs, heart, kidneys and eyes. Compound (3) demonstrated anthelmintic activity similar to that of albendazole by decreasing the number of larvae in the organs of mice and thus could form the basis of the development of a new anthelmintic drug.

Toxocara species infect a wide range of companion, domestic and wild animals as definitive and paratenic hosts, via multiple routes of transmission, producing long-lived tissue-inhabiting larvae and resistant eggs that can survive in the external environment. Therefore Toxocara and the disease it causes in humans, toxocariasis, represents an ideal aetiological agent for the development of the one health approach. However, despite increasing awareness of the public health significance of toxocariasis, gaps in our understanding of certain key aspects of the parasite's biology and epidemiology remain. These gaps hinder our ability to integrate research effort within the veterinary, medical and environmental disciplines. This review will highlight key deficits in our understanding of nine dimensions of Toxocara epidemiology and discuss a potential scenario to develop a more integrated, one health approach to improve our understanding of the prevention and control of this complex and cryptic zoonosis.

An open randomized study was carried out to assess the efficacy of diethylcarbamazine (DEC) and mebendazole (MBZ) across, respectively, 39 and 41 patients, all exhibiting clinical and biological features evocative of toxocariasis, together with a positive immunodiagnosis by Western blot using Toxocara larvae excretory-secretory antigens. Clinical impact of the disease was quantified by a score system (20 parameters). Post-treatment follow-up used also results from eosinophil counts from total and specific anti-Toxocara IgE quantitations, and from Western blots. All patients attended the control check-up 1 month after the end of treatment. Analysis of the results showed a similar good efficacy of DEC and MBZ on clinical score and eosinophil count that were significantly lowered. MBZ therapy was slightly more efficient on specific anti-Toxocara IgE kinetics, while total IgE mean titres were not affected by either DEC or MBZ treatment. Patients from the DEC group reported a significantly higher rate of adverse reactions, most of which could be due to parasite lysis. This fact could be a strong argument for treating human toxocariasis with MBZ.

Studies were conducted on the role of small mammals in maintaining toxocariasis foci in urban, rural and montane biotopes. The lowest relative density of small mammals was recorded in the urban locality and the highest in the rural and montane localities. Anti-Toxocara antibodies were most frequently detected in synanthropic and hemisynanthropic species Mus musculus, Apodemus agrarius and Micromys minutus – 32·0, 30·4 and 25·0%, respectively. The highest seropositivity was found in small mammals from the urban and rural localities – 22·2 and 21·6%, respectively. Toxocara canis was most prevalent in urban stray dogs (75·0%) and least prevalent in foxes from the montane locality (7·0%). The prevalence of Toxocara cati in cats at the urban, rural and montane localities was 66·2, 65·2 and 76·9%, respectively. In clinically healthy human populations, the highest seroprevalence was detected in the rural locality (14·0%). Children of the same area were 3 times more seropositive (12·9%) than those from the urban and montane localities (4·3 and 4·0%). Our studies suggest an important role for small mammals as paratenic hosts – reservoirs of Toxocara larvae – in maintaining toxocariasis foci. In this respect toxocariasis may be classified as an anthropopurgic focal zoonosis.

The seroprevalence of toxocariasis was investigated in 2129 school children ranging in age from 4 to 19 years. Infection, as measured by titre, was found to be high compared to values obtained from children in other countries, with 31% having a titre of ≥ 1:50 and 3·1% having titres of ≥ 1:800. Relalionships between seroprevalence and host factors including age, sex and location, and risk factors including geophagia, thumbsucking and pet ownership were explored. Age was found to be a significant factor in relation to infeclion with Toxocara. Males were significantly more infected than females, as were the inhabitants of rural schools versus urban schools. The percentage of seropositive children varied widely from school to school. Geophagia and pet ownership were found to be significantly associated with toxocariasis. Logistic regression analysis was used to model the relative contribution of these factors to infection wilh Toxocara. While this analysis identified factors which were highly significantly associated with Toxocara titre, the odds ratios were generally low indicating ihe low specificity of the model.

Infection with Toxocara canis is a common world-wide human helminthiasis, which rarely elicits central nervous system (CNS) impairment. A case-control study to investigate this discrepancy was carried out, in which the cases were 27 adult neurological inpatients for whom a definite aetiological diagnosis was lacking, and for whom positive immunodiagnosis of toxocariasis had been obtained, both in cerebrospinal fluid (CSF) and in serum. Two control groups were used. Controls were adult inpatients with other neurological diseases who had no evidence of T. canis infection of the CNS. Multivariate logistic regression analysis did not reveal any positive relation between case status and clinical signs. A significant association was observed between case status and an elevated CSF cell count. Rural residence, ownership of dogs, and dementia were shown to be risk factors for toxocaral infection of CNS. These results suggest that migration of T. canis larvae in the human brain does not frequently induce a recognizable neurological syndrome but is correlated with the association of several risk factors including exposure to dogs, a status possibly responsible for repeated low-dose infections.