Highlights of human toxocariasis

Visceral larva migrans in immigrants from latin america

To determine whether increased migration is associated with an increase in incidence of toxocariasis (visceral larva migrans), we analyzed clinical data obtained from immigrants from Latin America. Although infection with Toxocara sp. roundworm larvae is distributed worldwide, seroprevalence is highest in tropical and subtropical areas.

Toxocara canis myelitis: clinical features, magnetic resonance imaging (MRI) findings, and treatment outcome in 17 patients

Toxocara myelitis is a rare disease. Few cases have been reported in the literature. Patients present with myelopathy, occasional eosinophilia in blood and cerebrospinal fluid (CSF), with abnormal signals on magnetic resonance imaging (MRI). In the current study we report 17 cases of isolated Toxocara myelitis from a single tertiary referral center in Lebanon, with description of the clinical presentation, laboratory data, MRI findings, and response to antihelminthic treatment. Clinical and laboratory data were collected for 17 patients who presented with evidence of spinal cord disease. The clinical presentation included sensory, motor, and autonomic dysfunction, predominantly in the lower extremities. Patients exhibited a subacute or chronic course; this was either slowly progressive or remitting-relapsing with mild to moderate disability. The patients underwent extensive blood and CSF workup as well as MRI of the spinal cord and brain. Only 2 patients had a high eosinophil count in the CSF, although blood eosinophilia was seen in 6 patients. All patients tested positive for Toxocara canis antibodies in the blood and CSF. MRI of the spinal cord revealed a single characteristic lesion in the spinal cord with fusiform enlargement that was isointense on T1-weighted images and hyperintense on T2-weighted images. Nodular enhancement was seen after gadolinium injection. Treatment with albendazole, with or without steroids, resulted in marked neurologic improvement and normalization of the MRI in all patients.The finding of a single inflammatory MRI lesion in the spinal cord with positive Toxocara canis serology in the blood and CSF in cases of subacute or chronic myelitis suggests the diagnosis of Toxocara myelitis, irrespective of the presence of eosinophilia. Antihelminthic treatment is associated with a good outcome.

Seroprevalence of toxocariasis in hypereosinophilic individuals in Ahwaz, south-western Iran

Eosinophilia in human peripheral blood is caused by different agents, including toxocariasis. The present study aimed to evaluate the prevalence of toxocariasis in hypereosinophilic individuals in the city of Ahwaz, located in south-western Iran, using enzyme-linked immunosorbent assay and Western blot techniques. Serum samples were examined from 100 individuals with peripheral blood eosinophilia and also from another 100 individuals without eosinophilia as the control group. In hypereosinophilic individuals seroprevalence antibodies against Toxocara were found in 19 (19%), of whom 12 (63.15%) were female and 7 (36.85%) were male. Positive sera were subsequently confirmed by Western blot. All of the observed bands ranged from 24 to 100 kDa. Antibodies against Toxocara were found in 1% of the control group, but were not confirmed by Western blot. The results showed significant differences between the frequency of infection within age and gender (P < 0.05); the highest prevalence of infection was observed in adults. Differences between the hypereosinophilic and healthy individuals, in terms of Toxocara infection frequency, also proved significant (P < 0.05).The present study thus confirmed the significant prevalence of toxocariasis as a hygienic problem among hypereosinophilic individuals in this area. It is, therefore, necessary to examine these individuals for toxocariasis.

An extremely uncommon case of parasitic infection presenting as eosinophilic ascites in a young patient

We report the case of a 24-year-old male patient admitted for recent ascites and splenomegaly of unknown origin. The patient was referred to our institution with complaints of diarrhea, epigastric pain, abdominal cramping and weight loss over the past three weeks. The acute onset presented with colicky abdominal pain and peritoneal effusion. History revealed reduced appetite and weight gain of 7 kg over the last one month. His past medical history and family history was negative. He had no history of alcohol abuse or viral hepatitis infection. Laboratory data revealed normal transaminases and bilirubin levels, and alkaline phosphatase and gammaglutamyltransferase were within normal range. A diagnostic laparoscopy was performed which showed free peritoneal fluid and normal abdominal viscera. Upper gastrointestinal system endoscopy performed a few days later revealed diffuse severe erythematous pangastritis and gastroduodenal gastric reflux. Duodenal biopsies showed chronic nonspecific duodenitis. Antrum and corpus biopsies showed chronic gastritis. The ascitic fluid was straw-colored and sterile with 80% eosinophils. Stool exam was negative for parasitic infection. Treatment with albendazole 400 mg twice daily for 5 days led to the disappearance of ascites and other signs and symptoms. Three months after albendazole treatment the eosinophilic cell count was normal. The final diagnosis was consistent with parasitic infection while the clinical, sonographic and histological findings suggested an eosinophilic ascites. We emphasize the importance of excluding parasitic infection in all patients with eosinophilic ascites. We chose an alternative way (albendazole treatment) to resolve this clinical picture. With our alternative way for excluding this parasitic infection, we treated the patient and then found the cause.

Protective and risk factors for toxocariasis in children from two different social classes of Brazil

The aim of this study was to analyze the prevalence of Toxocara spp. antibodies in children from two different socioeconomic classes in the Presidente Prudente municipality, São Paulo State, Brazil, and the protective and risk factors associated with toxocariasis. One hundred and twenty-six middle-class (MC) and 126 disadvantaged children (DC) were included in this study. Anti-Toxocara ELISA test was performed in order to evaluate seroprevalence. A survey was applied to the children's guardians/parents in order to analyze the protective and risk factors. The overall prevalence was 11.1%, and of 9.5% (12/126) and 12.7% (16/126) for MC and DC subgroups, respectively. Toxocara seropositivity was inversely proportional to the family income. A high household income was considered a protective factor for toxocariasis in the total population and in both MC and DC subgroups. Being a girl was considered a protective factor for the total population and for both subgroups. Whilst being an owner of cat was a risk factor for children belonging to the total and for both MC and DC subgroups, having dog was considered as a risk factor for only the MC. Epidemiologic protective/factor risks can be distinct depending on the strata of the same population. Thus, it is relevant to evaluate these factors independently for different socioeconomic classes in order to design future investigations and programs for preventing the infection of human beings by Toxocara spp. and other geohelminths.

Potential immunological markers for diagnosis and therapeutic assessment of toxocariasis

In human toxocariasis, there are few approaches using immunological markers for diagnosis and therapeutic assessment. An immunoblot (IB) assay using excretory-secretory Toxocara canis antigen was standardized for monitoring IgG, IgE and IgA antibodies in 27 children with toxocariasis (23 visceral, three mixed visceral and ocular, and one ocular form) for 22-116 months after chemotherapy. IB sensitivity was 100% for IgG antibodies to bands of molecular weight 29-38, 48-54, 95-116, 121-162, >205 kDa, 80.8% for IgE to 29-38, 48-54, 95-121, > 205 kDa, and 65.4% for IgA to 29-38, 48-54, 81-93 kDa. Candidates for diagnostic markers should be IgG antibodies to bands of low molecular weight (29-38 and 48-54 kDa). One group of patients presented the same antibody reactivity to all bands throughout the follow-up study; in the other group, antibodies decayed partially or completely to some or all bands, but these changes were not correlated with time after chemotherapy. Candidates for monitoring patients after chemotherapy may be IgG antibodies to > 205 kDa fractions, IgA to 29-38, 48-54, 81-93 kDa and IgE to 95-121 kDa. Further identification of antigen epitopes related to these markers will allow the development of sensitive and specific immunoassays for the diagnosis and therapeutic assessment of toxocariasis.

In vitro and in vivo effects of Enterococcus faecalis CECT7121 on Toxocara canis

The aim of the present paper was to evaluate the larvicidal effect of Enterococcus faecalis CECT7121 (Ef7121) on the Toxocara canis cycle both in vitro and in vivo. For the in vitro experiments, T. canis larvae were incubated with the supernatants of Ef7121 (EI) and mutant Ef7121 (EIm), in a pre-culture of Ef7121 (EII) and in a fresh culture with Ef7121 (EIII) and the Ef7121 mutant strain (EIIIm). The viability of the larvae was calculated after a 48 h incubation. A significant reduction of the viability of T. canis larvae was observed in EI, EII and EIII. A decrease of this inhibitory effect was observed in EIm and EIIIm (p = 0.008). In the in vivo experiments, mice were orally inoculated with three doses of Ef7121. To study the probiotic persistence in the intestine, the animals were sacrificed every four days and their intestines were dissected. The initial average bacterial levels were 9.7 x 10(4) for Ef7121 (colony forming units/g). At the end of the assay the levels were 1.46 x 10(4). No bacterial translocation was detected in mesenteric lymphatic nodules and spleen. Ef7121 interference with the biological cycle was evaluated in mice challenged with T. canis. The interference was significant when the mice were challenged with probiotic and T. canis simultaneously (p = 0.001), but it was not significant when the challenge was performed 15 days after administration of the bacterial inoculum (p = 0.06). In conclusion, Ef7121 possessed in vitro and in vivo larvicidal activity.

Toxocara and Ascaris seropositivity among patients suspected of visceral and ocular larva migrans in the Netherlands: trends from 1998 to 2009

Toxocara canis, Toxocara cati and Ascaris suum are roundworms of dogs, cats and pigs, respectively, that can also infect humans. These zoonotic helminths have a worldwide distribution and are also endemic in the Netherlands. Infection with Toxocara sp. may result in visceral larva migrans (VLM) or ocular larva migrans (OLM) caused by the migrating larvae. Although A. suum has been reported to occasionally mature to the adult stage in humans, clinical cases of VLM suspected to be caused by A. suum have been described. Diagnosis of these helminth infections relies mainly on serology. Here we analyse the results from the Toxocara and Ascaris IgG-ELISA from a total of 2,838 serum samples from VLM and OLM suspected patients that were sent to our institution from 1998 to 2009. Results indicate that for each year the Ascaris seropositivity is significantly higher compared to the Toxocara seropositivity. Furthermore, while Toxocara seropositivity has decreased over time, the Ascaris seropositivity has not significantly changed for the past 12 years. The Ascaris and Toxocara seropositivity was also shown to increases with age and, while gender has no influence on the Ascaris seropositivity, males showed higher Toxocara seropositivity.

Presence of visceral larva migrans in the urinary bladder of a woman in khorramabad, iran

The presence of Visceral Larva Migrans (VLM) in a patient is reported. A 57-year- old woman suffering from right upper abdominal and suprapubic pain referred into a clinic in Khorramabad, Lorestan Province, Iran. A cystoscopy was performed and biopsy was taken. The light microscopic study showed a couple of larvae as well as mononuclear inflammatory cell- infiltration. Because occurrence of VLM is potentially problem in rural areas, it is recommended that an educational program to be initiated to prevent and control VLM infection in both rural and urban people. Clinicians also should consider the clinical features of visceral larva migrans.

Avaliação eosinofílica e soropositividade para anticorpos IgG anti-toxocara em crianças atendidas pelo Sistema Único de Saúde

OBJETIVO: Verificar a associação entre a presença de eosinofilia e a soropositividade para anticorpos IgG anti-Toxocara spp. em crianças atendidas pelo Sistema Único de Saúde no Noroeste do Paraná, Brasil. MÉTODOS: Estudo retrospectivo com crianças de sete meses a 12 anos, atendidas pelo Sistema Único de Saúde do Noroeste do Paraná, com teste ELISA para a pesquisa de anticorpos IgG anti-Toxocara spp. e contagem de eosinófilos (eosinofilia >600 células/mm³). RESULTADOS: Entre as 1.199 crianças, 386 (32,2%) apresentaram anticorpos IgG anti-Toxocara spp. A soroprevalência e a eosinofilia foram mais frequentes em crianças de sete meses a cinco anos. A eosinofilia foi observada em 7,8% dos pacientes soro-reagentes ao Toxocara spp.. CONCLUSÕES: Foi observada elevada prevalência de anticorpos anti-Toxocara spp., principalmente nos menores de cinco anos. Com exceção de algumas crianças que apresentaram sintomas respiratórios e presença de eosinofilia, a maioria foi assintomática e não mostrava eosinofilia. A pesquisa de eosinófilos é ferramenta secundária para o diagnóstico de toxocaríase.

Imaging of Toxocara canis larvae labelled by CFSE in BALB/c mice

Mice are used most often as a model for human toxocariasis caused by Toxocara canis larvae. Variety of symptoms developing during the infection reflects behaviour of the larvae, which are able to escape from the intestine and further invade and damage various host organs. In order to find an approach enabling observation on parasite behaviour in mouse in vivo, we used an epifluorescence method and a small animal imaging system (SAIS). Larvae of T. canis were labelled by carboxyfluorescein succinimidyl ester (CFSE) which incorporated on the parasite gastrointestinal tract. Following infection of BALB/c mice by CFSE-labelled larvae it has been observed that staining had no influence on viability and further migratory activity of the parasites through the host organs (the intestine, liver, lungs and brain) where they were detected by SAIS until day 17 p.i. In addition, the dye did not affect larval antigenic activity as well as the development of related immune response. Imaging of parasites labelled by CFSE, therefore, may represent a promising way to study behaviour of T. canis larvae in a paratenic host.

Emerging and established parasitic lung infestations

Many lung infestations from established and newly emerging parasites have been reported as a result of the emergence of HIV/AIDS, the increasing use of immunosuppressive drugs, increasing organ transplantations, the increase in global travel, and climate change. A renewed interest in parasitic lung infections has been observed recently because many protozoal and helminthic parasites cause clinically significant lung diseases. The diseases caused by these parasites may mimic common and complicated lung diseases ranging from asymptomatic disease to acute respiratory distress syndrome requiring critical care management. The availability of new molecular diagnostic methods and antiparasitic drugs enables early diagnosis and prompt treatment to avoid the morbidity and mortality associated with these infestations. Good hygiene practices, improvement in socioeconomic conditions, vector control measures, and consumption of hygienically prepared and properly cooked food are essential to reduce the occurrence of parasitic infestations.

Kinetics of Foxp3-expressing regulatory cells in experimental Toxocara canis infection

Foxp3-expressing cells have recently been recognized as a cornerstone for the homeostasis of the immune system, and as key cells in many infectious diseases. Moreover, they have been found to contribute to the regulation of parasite-induced immunopathology in many parasitic infections. However, their role in Toxocara-induced immunopathology has not yet been investigated. The aim of this study is to assess the kinetics of Foxp3-expressing regulatory cells during the course of experimental infection by Toxocara canis (T. canis). Foxp3+ cells were identified in the liver by immunohistochemistry, and splenic Foxp3 gene expression was evaluated. We found significantly progressive increase in Foxp3-expressing cell counts in the liver starting from 5 weeks p.i. These cells were detected within and around Toxocara-induced granulomas as well as in isolated inflammatory foci in the portal tracts or within the hepatic parenchyma. Likewise, expression of Foxp3 mRNA in the spleen significantly increased at 5 and 16 weeks p.i. Furthermore, immunization of mice with Toxocara excretory-secretory antigen prior to experimental infection caused earlier mobilization and recruitment of Foxp3+ cells to the liver and enhanced splenic expression of Foxp3 transcripts. These results suggest a potential role of Foxp3-expressing regulatory cells in the evolution of the immunopathological events during infection by T. canis.

Emerging zoonoses in the southern United States: toxocariasis, bovine tuberculosis and southern tick-associated rash illness

The majority of emerging diseases in humans have been linked to zoonotic pathogens originating in domestic animals or wildlife. This is a public health concern because zoonotic infections affect several aspects of the society. The complex interactions among pathogen, host and environment also pose challenges in estimating the true burden of those infections. However, the recent development of new molecular diagnostic tools has allowed for better diagnosis of zoonotic infections. This review focuses on 3 emerging zoonoses, namely toxocariasis, bovine tuberculosis and southern tick-associated rash illness, and demonstrates that these infections may be more prevalent in the southern United States than previously recognized. This review places special emphasis on the recent epidemiologic trends, intra/interspecies transmission and clinical features of each of these zoonoses. In addition, treatment and prevention for each zoonotic pathogen are discussed. Clinicians working in the southern United States should be aware of the presence of those zoonotic infections.

A case of recurrent toxocariasis presenting with urticaria

Human toxocariasis is the most prevalent helminthiasis in Korea and other industrialized countries. The clinical features of toxocariasis are diverse, according to the involved organ. Typically, Toxocara spp. infection is easily treated with 400 mg albendazole twice a day for 5 days. However, we experienced a case of recurrent toxocariasis that was refractory to this standard therapy and presented with urticaria, an uncommon symptom in toxocariasis. A 35-year-old male visited our emergency room because of abdominal pain. He had recently consumed raw cow liver (3 weeks prior to presentation). Laboratory analyses revealed eosinophilia (1,612 cells/µL) and increased total IgE (3,060 IU/mL). Chest X-ray showed multiple lung nodules in both lungs, and computed tomography revealed multiple ground-glass opacities in both lungs and multiple tiny liver abscesses. Liver biopsy revealed an eosinophilic abscess. Enzyme-linked immunosorbent assay findings for Toxocara antigens were positive (optical density, 2.140), leading to a diagnosis of toxocariasis. We initiated a 5-day treatment with albendazole and prednisolone; however, 6 days after completing the treatment, the patient again experienced urticaria and severe itching that could not be controlled by antihistamines or hydrocortisone cream. A second bout of eosinophilia suggested recurring toxocariasis, for which we prescribed a second round of albendazole. Despite an initial improvement in his symptoms, the patient returned after 6 weeks complaining of abdominal pain for 6 hours, which was reminiscent of his first attack; he also exhibited eosinophilia. Accordingly, albendazole was administered once more for an additional 3 weeks, and his symptoms resolved.

[Acute respiratory distress syndrome due to Toxocara cati infection]

Human toxocarosis is a helminthozoonosis due to the migration of toxocara species larvae throughout the human body. Lung manifestations vary and range from asymptomatic infection to severe disease. Dry cough and chest discomfort are the most common respiratory symptoms. Clinical manifestations include a transient form of Loeffler's syndrome or an eosinophilic pneumonia. We report a case of bilateral pneumonia in an 80 year old caucasian man who developed very rapidly an acute respiratory distress syndrome, with a PaO2/FiO2 ratio of 55, requiring mechanical ventilation and adrenergic support. There was an increased eosinophilia in both blood and bronchoalveolar lavage fluid. Positive toxocara serology and the clinical picture confirmed the diagnosis of the "visceral larva migrans" syndrome. Intravenous corticosteroid therapy produced a rapid rise in PaO2/FiO2 before the administration of specific treatment. A few cases of acute pneumonia requiring mechanical ventilation due to toxocara have been published but this is, to our knowledge, is the first reported case of ARDS with multi-organ failure.

Serological, clinical and epidemiological evaluation of toxocariasis in urban areas of south Brazil

Toxocariasis is a worldwide public-health problem that poses major risks to children who may accidentally ingest embryonated eggs of Toxocara. The objectives of this study were to investigate the occurrence of anti-Toxocara spp. antibodies in children and adolescents and the variables that may be involved, as well as environmental contamination by Toxocara spp. eggs, in urban recreation areas of north central mesoregion, Paraná State, Brazil. From June 2005 to March 2007. a total of 376 blood samples were collected by the Public Health Service from children and adolescents one to 12 years old, of both genders. Samples were analyzed by the indirect ELISA method for detection of anti-Toxocara antibodies. Serum samples were previously absorbed with Ascaris suum antigens, and considered positive with a reagent reactivity index >1. Soil samples from all of the public squares and schools located in the four evaluated municipalities that had sand surfaces (n = 19) or lawns (n = 15) were analyzed. Of the 376 serum samples, 194 (51.6%) were positive. The seroprevalence rate was substantially higher among children aging one to five years (p = 0.001) and six to eight years (p = 0.022). The clinical signs and symptoms investigated did not show a statistical difference between seropositive and seronegative individuals (p > 0.05). In 76.5% of the investigated recreation places, eggs of Toxocara were detected in at least one of the five collected samples. Recreation areas from public schools were 2.8 times more contaminated than from public squares. It is important to institute educational programs to inform families and educators, as well as to improve sanitary control of animals and cleaning of the areas intended for recreation in order to prevent toxocariasis.

Seroepidemiological investigation of toxocariasis in the isparta region of Turkey

BACKGROUND

Toxocariasis is a common disease around the world. Our objective was to determine Toxocara seroprevalence in humans in the city of Isparta, Southwest Turkey, in respect of some determinants such as age, socio-economic level, residence in city center or rural area etc.

METHODS

Five hundred and thirty four individual participants from Isparta center and 85 from Asagi Gokdere village were included in the study. T. cati specific antibodies were analyzed using excretory-secretory (ES)-enzyme-linked immunosorbent assay (ELISA) method.

RESULTS

T. cati antibodies were detected as positive in 73 (13.6%) of 534 samples which were collected from subjects living in the city center and 24 (28.2%) of 85 samples from Asagi Gokdere village. Toxocara seropositivity was detected among 15.6% of whole study group. The seroprevalence of toxocariasis was significantly higher among subjects from village than in subjects from city center (P=0.001). While gender, high school education, source of the water which is used, family income and geophagia/eating nail behaviors were the features which were detected as being associated with toxocariasis seropositivity (odds ratios=0.5; 6.52; 3.61; 0.43; 0.13 respectively), owning dogs or cats and hand washing were detected as being not associated with toxocariasis seropositivity (P>0.05). Furthermore, Toxocara seropositivity was significantly higher among subjects in 0-10 than >40 year-old group (P=0.02).

CONCLUSION

It can be suggested that untreated lost pet population, environmental contamination, and way of life have influence on the epidemiology of toxocariasis.

Human toxocariasis: a seroepidemiological survey in the Amazonian city of Yurimaguas, Peru

The aim of this study was to determine the seroprevalence of the infection by Toxocara in the general population of the Amazonian city of Yurimaguas, Peru. From March to August 2008, a total of 300 subjects were sampled and tested by means of a Toxocara ELISA-IgG test. A clinical and epidemiological questionnaire was used to assess the symptomatology and risk factors associated with human toxocariasis. The overall rate of seropositivity was 35.66%, with a significant high proportion in children (p < 0.001). The clinical evaluation revealed that 95.33% of the seropositive group had some type of symptomatology: headache (66.36%), respiratory compromise (63.55%), abdominal pain (54.21%), cutaneous signs (40.19%) and ocular manifestations (36.45%), and almost all of them were statistically significant (p < 0.001). Furthermore, 56.07% of the seropositive subjects presented at least one intestinal pathogen parasite with predominance of helminthes, but without significant association (p = 0.334). The analysis of risk factors showed only that the use of public places and geophagia exhibited a significant association with the seropositivity (p < 0.001). Clinical, serological and epidemiological findings associated to infection with Toxocara were observed in the present study and future studies should be done to assess this serious health problem.

The increase in seroprevalence to Toxocara canis in asthmatic children is related to cross-reaction with Ascaris suum antigens

BACKGROUND

It has been suggested that the presence of Toxocara canis larvae in lungs is an underlying factor in the onset of asthma. Although the association of asthma and seropositivity to Toxocara has been observed, there are no studies that indicate whether these antibodies are specific against T. canis antigens.

METHODS

Seroprevalence to T. canis excretion-secretion antigens (TcES Ag) were compared between asthmatic children (n=285) and non-asthmatic children (n=152), using IgG-ELISA and IgE-ELISA. The recognition patterns of TcES Ag were determined using Western blot (WB).

RESULTS

IgG-ELISA seroprevalence was 30.8% for asthmatic children and 19.7% for non-asthmatic children (p<0.05). IgE-ELISA seroprevalence was 7.7% for asthmatic children and 6.5% for non-asthmatic children, respectively (p>0.05). Sera of both groups positive to IgG-ELISA recognised 11 TcES Ag bands for IgG. No differences between the groups were observed regarding recognition patterns; the asthmatic group, however, presented significantly higher cross-reaction to Ascaris suum somatic antigens (AsS Ag) than the non-asthmatic group. Sixty-three sera from asthmatic children positive to IgG-ELISA were evaluated by WB for IgE and 58.7% revealed a recognition pattern for IgE. In the group of non-asthmatic children positive to IgG-ELISA, 80% presented IgE band recognition. No differences were observed between the groups regarding recognition patterns.

CONCLUSIONS

The results observed suggest that differences in seroprevalence determined by IgG-ELISA between groups of asthmatic and non-asthmatic children reported by other authors occur because of a higher frequency of cross-reaction in asthmatic children.

Human toxocariasis: contribution by Brazilian researchers

In the present paper the main aspects of the natural history of human infection by Toxocara larvae that occasionally result in the occurrence of visceral and/or ocular larva migrans syndrome were reviewed. The contribution by Brazilian researchers was emphasized, especially the staff of the Tropical Medicine Institute of São Paulo (IMT).

Biochemical and immunopathological changes in experimental neurotoxocariasis

Toxocariasis is a widespread soil-transmitted parasitic disease. Toxocara canis larvae migrate through the tissues with a special predilection for the central nervous system. Recently, neurotoxocariasis is being diagnosed in humans with increasing frequency due to improved diagnostic tools. The present study aimed at exploring the biochemical and immunopathological alterations in the brain in experimental T. canis infection. For this purpose, 75 Toxocara-infected mice were sacrificed at 2, 5, and 16 weeks post-infection. The brains were removed and assayed for total larval count, pro-inflammatory cytokines (TNF-alpha, IL-6), and central neurotransmitters (gamma-aminobutyric acid, glutamate, dopamine, norepinephrine, and serotonin). Brain sections were also stained for histopathological study, and for assessment of the expression of inducible nitric oxide synthase (iNOS), and glial fibrillary acidic protein (GFAP) by immunohistochemical methods. We found that larval recovery showed progressive increase over the course of infection. Furthermore, the infected mice displayed increased expression of pro-inflammatory cytokines and iNOS, as well as significant disturbances in neurotransmitter profile. Astrocytic activation, evidenced by enhanced expression of GFAP, was also manifest in infected animals. These changes were maximal in the chronic stage of infection or intensified over time. In conclusion, experimental neurotoxocariasis is associated with significant biochemical, immunological, and pathological changes.

Seroprevalence of human toxocariasis in Andean communities from the Northeast of Lima, Peru

The aim of this study was to assess the seroprevalence of human toxocariasis in three Andean communities from the Northeast of Lima, Peru. A total of 303 subjects including children and adults were studied and blood samples were collected to detect anti-Toxocara antibodies by ELISA-IgG test and by hematological examination; stool samples were collected also for parasitological examination. The overall seroprevalence of toxocariasis observed in the total population was 20.46%, with a significant high proportion in children from one to 10 years old (p = 0.034). Among the subjects with positive serology, 32.26% of them had respiratory disturbances, 22.58% hepatomegaly, 17.74% ocular signs or symptoms, 14.51% abdominal pain, 9.68% neurological involvement, and 4.84% cutaneous signs, but none of these clinical features were associated to a positive serology by multivariate analysis. Furthermore, 79.03% of seropositive subjects also harbored at least one intestinal parasite, which was associated to a positive serology (p < 0.05). The presence of pets within the houses, a previous history of pica or geophagia and the use of public places were also present in this population, but only the latter was associated to the serology (p < 0.05). In conclusion, clinical, serological, and epidemiological evidences for larval Toxocara infection were found in the studied population.

Toxocariasis might be an important cause of atopic myelitis in Korea

Atopic myelitis is defined as myelitis with atopic diasthesis but the cause is still unknown. Toxocariasis is one of the common causes of hyperIgEaemia that may lead to neurologic manifestations. The purpose of this study was to evaluate the sero-prevalence of Toxocara specific IgG Ab among the atopic myelitis patients. We evaluated the medical records of 37 patients with atopic myelitis whose conditions were diagnosed between March 2001 and August 2007. Among them, the 33 sera were analyzed for specific serum IgG Ab to Toxocara excretory-secretory antigens (TES). All of 37 patients had hyperIgEaemia. Specific IgE to D. pteronyssinus and D. farinae was detected in 22 (64.7%) and 34 (100%) patients, respectively, of the 34 patients. Thirty-one of 33 patients (93.9%) were found to be positive by TES IgG enzyme-linked immunosorbent assay (ELISA). Based on the image findings of eosinophilic infiltrations in the lung and liver, 8 patients had positive results. These results inferred that the prevalence of toxocariasis was high in patients with atopic myelitis. Our results suggest that toxocariasis might be an important cause of atopic myelitis and Toxocara ELISA is essential for evaluating the causes of atopic myelitis.

Differentiation of larva migrans caused by Baylisascaris procyonis and Toxocara species by Western blotting

Baylisascaris procyonis and Toxocara species are two important causes of larva migrans in humans. Larva migrans caused by Toxocara spp. is well known and is diagnosed serologically by enzyme immunoassay. Over a dozen cases of larva migrans and associated eosinophilic encephalitis caused by B. procyonis have also been reported, and at least a dozen additional cases are known. An enzyme-linked immunosorbent assay (ELISA) using the excretory-secretory (ES) antigen of B. procyonis larvae is currently being used in our laboratory as an aid in the diagnosis of this infection in humans. Clinically affected individuals show very high reactivity (measured as the optical density) on this ELISA; however, a one-way cross-reactivity with Toxocara spp. has been observed. As an approach to differentiate these two infections based on serology, we performed Western blots, wherein the B. procyonis ES antigen was reacted with serum samples from individuals known to be positive for either Toxocara spp. or B. procyonis larva migrans. Western blot results showed that B. procyonis antigens of between 30 and 45 kDa were specifically identified only by the sera from individuals with Baylisascaris larva migrans, thus allowing for differentiation between the two infections. This included human patient serum samples submitted for serologic testing, as well as sera from rabbits experimentally infected with B. procyonis. When used in conjunction with the ELISA, Western blotting could be an efficient tool for diagnosis of this infection in humans.

Recovery threshold of Toxocara canis eggs from soil

The purpose of this study was to evaluate the threshold of Toxocara canis eggs form soil samples through utilisation of a centrifuge-flotation technique (CFT). Aliquots of soil (1g each) were artificially contaminated with known numbers of T. canis eggs (1, 10, 25, 50, 100, and 200 eggs). The threshold was evaluated based on a CFT using zinc sulphate (Zn(2)SO(4)) and sodium nitrate (Na(2)NO(3)) solutions at a specific gravity of 1.20. The number of eggs recovered was directly proportional to the number of eggs employed to seed the soil. Both solutions enabled full recovery of samples containing merely three eggs; only Zn(2)SO(4) demonstrated efficiency in soil contaminated with a single egg. A recovery rate of 100% was obtained for all tests with samples containing 10 and 25 eggs for Zn(2)SO(4) and Na(2)NO(3), respectively(.) There was no difference in the mean number of recovered eggs regarding either the efficacy of the solutions or the repetition of evaluations in the same trial (p>0.05). Therefore, the CFT is efficient for the detection of Toxocara eggs, even in samples containing low egg numbers.

Influence of variables on centrifuge-flotation technique for recovery of Toxocara canis eggs from soil

The purpose of this study was to evaluate the influence of variables in a flotation technique for the recovery of Toxocara canis eggs from soil. The trials were done under standardized conditions on one gram of previously sterilized soil samples contaminated with 200 eggs of T. canis. The following variables were evaluated in serial steps: sieving; type of wash; time of stirring; resuspension of sediment; solution flotation. Centrifuge-flotation in sodium nitrate (d = 1.20 g/cm³) was adopted as an initial technique, using Tween 80 (0.2%) and decinormal sodium hydroxide as solutions for washing the samples. Ten tests were done to compare the variables, using counting in triplicate. The sieving of the material reduced significantly the recovery of eggs (p < 0.001) and the number of eggs recovered was higher when the sediment was resuspended (p < 0.05). After standardization, flotation solutions sodium chloride, zinc sulfate, sodium dichromate, magnesium sulfate, and sodium nitrate (d = 1.20g/cm³) were compared. The best results were obtained by using zinc sulfate solution. In conclusion, the chances of recovering T. canis eggs from samples using flotation solutions can be increased by washing of soil twice using distilled water, and resuspension of sediment. On the other hand, the sieving procedure can drastically reduce the number of eggs.

Seroprevalence of Toxocara canis infection among asymptomatic children with eosinophilia in Croatia

A total of 142 serum specimens from Croatian children aged 3-18 years, with peripheral eosinophilia and without any clinical symptoms, were tested for the presence of Toxocara canis IgG antibodies using an enzyme-linked immunosorbent assay (ELISA) and Western blot method. The overall T. canis seropositivity rate in the samples tested was 31%. There was no statistical difference in the seroprevalence rate between boys (32.1%) and girls (29.7%, chi2 = 0.092, P = 0.761). The T. canis seropositivity varied significantly between age groups both in boys (Fisher's test P < 0.001) and girls (Fisher's test P = 0.007). The highest seroprevalence rate was found in boys aged 11-14 (42.9%) and girls aged 7-10 (44.2%). Our results showed a high seroprevalence rate of T. canis infection among children with eosinophilia. It is important that testing for toxocariasis should be included in a differential diagnosis of eosinophilia, especially in children.

The co-occurrence of Toxocaraocular and visceral larva migrans syndrome: a case series

Introduction

Ocular toxocarosis associated with high peripheral eosinophilia and together with systemic signs of visceral damage has been reported sporadically. Eye infections caused by numerous migrating larvae of Toxocara parasites, probably due to re-invasion or delayed reactivation, and leading to a progressive loss of vision is relatively rare. We report three atypical cases of toxocarosis with the co-existence of ocular larva migrans syndrome and generalized signs of Toxocara infection in schoolboys.

Case presentation

Two children aged 8 and 14 years respectively, with symptomatic ocular and visceral larva migrans syndromes, and one 16-year-old adolescent with chronic multifocal eye invasion, characterized by severe granulomatous retinochoroiditis with unilateral blindness, chronic abdominal pain and generalized synthesis of total immunoglobulin E antibody are described. The three patients, heavily infected with Toxocara species were boys of Polish origin. Ocular location of the parasite was confirmed by the detection of intraocular synthesis of specific anti-Toxocara immunoglobulin G antibody in aqueous humour samples from the affected eyes. Immunological parameters of tissue eosinophilia, allergy or hypersensitivity reactions to the presence of the migrating Toxocara parasites were analysed. Irreversible eye complications were observed in the patients with high level of exposure to Toxocara species in a contaminated environment, with a suggestion of possible re-activation or re-infection by different species or strains of the parasite.

Conclusions

Wide promotion of sanitary education is strongly justified in children and adolescents in Toxocara endemic areas in order to reduce the potential risk of primary invasion or re-infection with the parasites, which can lead to a severe course or progression of the disease. A long-term clinical follow-up and more intensive anti-parasitic treatment is recommended in patients with subclinical and overt forms of toxocarosis to prevent later reactivation of the migrating larvae in tissues.

The co-occurrence of Toxocara ocular and visceral larva migrans syndrome: a case series

INTRODUCTION

Ocular toxocarosis associated with high peripheral eosinophilia and together with systemic signs of visceral damage has been reported sporadically. Eye infections caused by numerous migrating larvae of Toxocara parasites, probably due to re-invasion or delayed reactivation, and leading to a progressive loss of vision is relatively rare. We report three atypical cases of toxocarosis with the co-existence of ocular larva migrans syndrome and generalized signs of Toxocara infection in schoolboys.

CASE PRESENTATION

Two children aged 8 and 14 years respectively, with symptomatic ocular and visceral larva migrans syndromes, and one 16-year-old adolescent with chronic multifocal eye invasion, characterized by severe granulomatous retinochoroiditis with unilateral blindness, chronic abdominal pain and generalized synthesis of total immunoglobulin E antibody are described. The three patients, heavily infected with Toxocara species were boys of Polish origin. Ocular location of the parasite was confirmed by the detection of intraocular synthesis of specific anti-Toxocara immunoglobulin G antibody in aqueous humour samples from the affected eyes. Immunological parameters of tissue eosinophilia, allergy or hypersensitivity reactions to the presence of the migrating Toxocara parasites were analysed. Irreversible eye complications were observed in the patients with high level of exposure to Toxocara species in a contaminated environment, with a suggestion of possible re-activation or re-infection by different species or strains of the parasite.

CONCLUSIONS

Wide promotion of sanitary education is strongly justified in children and adolescents in Toxocara endemic areas in order to reduce the potential risk of primary invasion or re-infection with the parasites, which can lead to a severe course or progression of the disease. A long-term clinical follow-up and more intensive anti-parasitic treatment is recommended in patients with subclinical and overt forms of toxocarosis to prevent later reactivation of the migrating larvae in tissues.

Ocular lesions in gerbils (Meriones unguiculatus) infected with low larval burden of Toxocara canis: observations using indirect binocular ophthalmoscopy

To study the frequency of ocular lesions in 30 gerbils infected with 100 embryonated eggs of Toxocara canis, indirect binocular ophthalmoscopy was performed 3, 10, 17, 24, 31 and 38 days after infection. All the animals presented larvae in the tissues and 80% presented ocular lesions. Hemorrhagic foci in the choroid and retina were present in 92% of the animals with ocular lesions. Retinal exudative lesions, vitreous lesions, vasculitis and retinal detachment were less frequent. Mobile larvae or larval tracks were observed in four (13.3%) animals. Histological examination confirmed the ophthalmoscopic observations, showing that the lesions were focal and sparse. In one animal, there was a larva in the retina, without inflammatory reaction around it. The results demonstrated that gerbils presented frequent ocular lesions after infection with Toxocara canis, even when infected with a small number of embryonated eggs. The lesions observed were focal, consisting mainly of hemorrhages with signs of reabsorption or inflammation in different segments of eye, and differing from the granulomatous lesions described in ocular larva migrans in humans.

Development and evaluation of a sensitive and specific assay for diagnosis of human toxocariasis by use of three recombinant antigens (TES-26, TES-30USM, and TES-120)

Diagnosis of human toxocariasis currently relies on serologic tests that use Toxocara excretory-secretory (TES) antigen to detect immunoglobulin G (IgG) antibodies to the larvae. In general, however, these assays do not have adequate specificity for use in countries in which other soil-transmitted helminths are endemic. The use of recombinant antigens in these assays, however, is promising for improving the specificity of the diagnosis of toxocariasis. Toward this goal, we developed an IgG4 enzyme-linked immunosorbent assay (ELISA) involving three recombinant antigens: rTES-30USM (previously produced), rTES-26, and rTES-120. The latter two antigens were produced by reverse transcription-PCR cloning; subcloned into glutathione S-transferase (GST)-tagged and His-tagged prokaryotic expression vectors, respectively; and expressed in Escherichia coli. The recombinant proteins were subsequently purified by affinity chromatography using GST and His-Trap resins. The diagnostic potential of each purified recombinant antigen was tested with various immunoglobulin classes (IgG, IgM, and IgE) and IgG subclasses. The IgG4 ELISA was determined to have the highest specificity and was further evaluated using a panel of serum samples. The rTES-26 IgG4 ELISA showed 80.0% (24/30 samples positive) sensitivity, and both the rTES-30USM IgG4 ELISA and rTES-120 IgG4 ELISA had 93.0% (28/30) sensitivity. Combined use of rTES-120 and rTES-30 IgG4 ELISA for the diagnosis of toxocariasis provided 100% sensitivity. The specificities of rTES-26, rTES-30USM, and rTES-120 antigens were 96.2%, 93.9%, and 92.0%, respectively. These results indicate that the development of a diagnostic test using the three recombinant antigens will allow for more-accurate detection of toxocariasis.

Frequency of eosinophilia and risk factors and their association with Toxocara infection in schoolchildren during a health survey in the north of Lima, Peru

During a health survey in a primary school from the district of Carabayllo (North of Lima, Peru), 200 schoolchildren (96 male and 104 female between five to 12 years old) were randomly selected and divided in two groups (as positive or negative group), according to the serologic result of the Toxocara ELISA test from a total population of 646 schoolchildren. All children were analyzed by hematologic tests to determinate the frequency of eosinophilia and leukocytosis. Additionally, all clinical and epidemiological data were also analyzed to determine their association with toxocariasis. From group of children with positive serology, 40% had some type of eosinophilia in contrast to 19% of children with negative serology, and their association was statistically significant (OR = 2.84, p < 0.001). From all signs and symptoms evaluated, only 'dry cough' was more frequent and statistically significant in the positive serology group (OR = 2.79, p < 0.001). Almost all risk factors evaluated were highly frequent and statistically associated to the positive serology. In conclusion, the presence of eosinophilia and the risk factors evaluated in this population were frequently associated to human toxocariasis.

Frequency of human toxocariasis in a rural population from Cajamarca, Peru determined by DOT-ELISA test

The aim of this study was to estimate the frequency of human toxocariasis in Cauday district, Cajamarca, Peru, using a dot-ELISA test. From June to October 2005, a total of 256 adult subjects were studied. Blood samples were collected for serology by a dot-ELISA test and for hematological examination. Parasitological examination was also carried out in stool samples to check cross-reactions in the dot-ELISA. The frequency observed was 44.92%, with a significant higher proportion of positivity in male subjects. From subjects with positive serology, 45.6% had respiratory symptoms, 40.44% abdominal pain, 32.35% hepatic symptoms, 14.7% cutaneous signs, 13.23% ocular manifestations, 43.38% eosinophilia, and all of these were statistically associated to serology. Among the population evaluated, 90.23% (231/256) were parasitized. From subjects with positive serology, 92.17% had at least one intestinal parasite and the most frequent were: Blastocystis hominis (68.38%), Giardia lamblia (28.68%), Hymenolepis nana (20.0%), Ascaris lumbricoides (15.65%), Entamoeba histolytica/E. dispar (13.24%), Cyclospora cayetanensis (4.41%), Cryptosporidium sp. (1.47%), Enterobius vermicularis (0.87%), Strongyloides stercoralis (0.87%), Taenia sp. (0.87%), and Trichuris trichiura (0.87%). The rate of false positives in the dot-ELISA test was improved by serum absorption each with A. suum antigens, with a decrease of cross-reactions. In conclusion, human toxocariasis is highly frequent in this population and some risk factors like dog/cat ownership, presence of pets within house, and previous history of geophagia were observed in the present study.

Toxocara seropositivity in Sri Lankan children with asthma

BACKGROUND

Toxocariasis occurs in humans due to infection with Toxocara canis or T. cati, the nematode parasites of dogs and cats, respectively. The relationship between toxocariasis and asthma is complex, with some studies demonstrating that children with asthma were more likely to be Toxocara seropositive as compared to non-asthmatic children, and other studies indicating no such significant relationship. The aim of the present study was to investigate Toxocara seropositivity and its association with asthma in a selected group of Sri Lankan children.

METHODS

Two groups of children were studied: group 1 included 100 children with confirmed bronchial asthma who were on regular inhaler steroid treatment for asthma; group 2 included 96 children who did not have physician-diagnosed asthma or upper respiratory tract infections, attending the same hospital. Diagnosis of Toxocara seropositivity was based on IgG Toxocara Microwell Serum Elisa Kits. Enzyme-linked immunosorbent assay was regarded as positive for a reading of 0.3 optical density units. Stool samples were examined for helminth ova.

RESULTS

Toxocara seropositivity in children with asthma was 29% and this was significantly more than Toxocara seropositivity among non-asthmatic children (P < 0.001). Toxocara seropositivity was identified as a significant risk factor of asthma in a univariate model. Eosinophilia was seen in a significantly higher proportion of non-asthmatic and asthmatic children who were Toxocara seropositive. Toxocara seropositivity, however, was not identified as a significant risk factor in a multivariate model.

CONCLUSIONS

The analysis confirmed previously identified risk factors for asthma but there was no association between the helminth parasitic infection, toxocariasis and bronchial asthma in children.

Ultrastructural localization of Toxocara canis larval antigen reacted with a seropositive human serum

Excretory-secretory products of Toxocara canis larvae have been considered as a major functional antigen in immune responses against toxocariasis. We studied ultrastructural localization of T. canis second-stage larval antigen using a seropositive human serum under immunogold electron microscopy. High-density gold particles were observed in the secretory cells, excretory duct, intestinal epithelium, and cuticle of the larval worm sections. The distribution of the positive reactions in the larval worms suggests that the nature of the antigen is excretory-secretory antigen including waste metabolites and secretory enzymes.

How common is human toxocariasis? Towards standardizing our knowledge

Our understanding of the global impact and cost of human toxocariasis is poor because there is insufficient clinical awareness and no clear repository for the efficacy of clinical, laboratory and treatment interventions. Uniform clinical and laboratory investigative approaches maximize disease diagnosis. International collaboration is required to develop web-based, professional educational support, surveillance questionnaires and standardized serodiagnostic criteria. Determining clinical benefits and treatment outcomes using less crossreactive antigens will enhance clinical and treatment interventions. Increased liaison will identify realistic occurrence and prevalence data and cost benefits of intervention. Web-based centres of excellence and repositories of current knowledge, which augment current veterinary and public health educational sites, should be supported. Expected outcomes should be capable of addressing the clinical and financial burdens of this treatable disease.

Impact of toxocariasis in patients with unexplained patchy pulmonary infiltrate in Korea

Toxocariasis is one of the causes of pulmonary eosinophilic infiltrate that is increasing in Korea. This study was designed to identify the prevalence of toxocara seropositivity in patients with unexplained pulmonary patchy infiltrate and to evaluate associated factors. We evaluated 102 patients with unexplained pulmonary patchy infiltrate on chest computed tomography (CT) scan. As a control set, 116 subjects with normal chest CT were also evaluated. History of allergic disease, drug use, parasitic disease and raw cow liver intake were taken. Blood eosinophil count and total IgE level were measured. Specific serum IgG antibody to Toxocara canis larval antigen and specific IgG antibodies to 4 other parasites were measured by enzyme-linked immunosorbent assay (ELISA). In the infiltrate group, 66.7% subjects were toxocara seropositive whereas 22.4% of the control group were seropositive (p<0.001). In the infiltrate group, patients with a history of eating raw cow liver (odds ratio [OR], 7.8) and patients with eosinophilia (OR, 5.2) had a higher incidence of toxocara seropositivity. Thirty-five percent of toxocara seropositive patients with infiltrate exhibited migrating infiltrate and 48% had decreased infiltrate on the follow-up CT. We recommend that toxocara ELISA should be performed in patients with unexplained pulmonary patchy infiltrate, and that the eating of raw cow liver should be actively discouraged.

Recurrent cerebral larva migrans: A case report and review of literature

Cerebral larva migrans (CLM) is an uncommon and rarely diagnosed entity. We report here a histopathologically proven case of CLM in a 13 year-old girl, who presented with bilateral focal seizures, right hemiparesis, and lapsed into altered sensorium prior to admission. Her CT scan was suggestive of a granulomatous lesion which eventually turned out to be CLM (toxocariasis). Interestingly, the lesion recurred after excision, with a confusing clinical picture. Following the second surgery, the pathology was reconfirmed and cure was provided for the disease. There has been no further intracranial recurrence during the past ten years although she developed cutaneous lesions.