Development of a low-cost copro-LAMP assay for simultaneous copro-detection of Toxocara canis and Toxocara cati.

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 (15­120 min), and different concentrations of malachite green dye (0.004­0.4% 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 10­100 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.

Assessment of the diagnostic value of specific anti-Toxocara IgA in Slovakian patients suspected to have toxocarosis.

Human toxocarosis is one of the most widespread and prevalent helminthic zoonosis in many countries, including Slovakia. The aim was to evaluate the usefulness of IgA anti-Toxocara antibody detection in the serodiagnosis of toxocarosis. The levels of specific IgA antibodies were determined by excretory-secretory (ES)-enzyme-linked immunosorbent assay (ELISA). The IgA seropositivity in IgG anti-Toxocara seropositive patients (n = 52) was 32.7% and found to be highest in the oldest age groups (P = 0.026). The presence of IgA in suspected patients for toxocarosis were evaluated in respect to some characteristics of examined persons. Substantially higher IgA seropositivity was detected in patients with increased total IgE (44.8%) than in subjects with a normal level of IgE (17.4%; P = 0.036). No associations (P > 0.05) were found between IgA seropositivity and sex, level of specific IgG antibodies, avidity of IgG, eosinophilia, domicile, geophagia, traveling abroad, dog/cat ownership, or clinical symptoms. The IgA-ELISA showed sensitivity of 57.1% and specificity of 100%. Mild correlations (r = 0.302, r = 0.305, r = - 0.409) were observed between the levels of anti-Toxocara IgA antibodies and age, the amounts of eosinophils and IgA antibody levels, the amounts of eosinophils, and the values of IgG avidity, respectively. The presence of anti-Toxocara IgA may facilitate the diagnosis of toxocarosis and may well be useful for the determination of acute Toxocara infection. Moreover, this test should be accompanied by other immunological markers of examined patients (e.g., increased total IgE, eosinophilia, and low-avidity IgG antibodies).

Assessment of U.S. Pediatrician Knowledge of Toxocariasis.

Toxocariasis, one of a group of parasitic diseases known as neglected parasitic infections, is a disease caused by the larvae of two species of Toxocara roundworms, Toxocara canis, from dogs, and less commonly Toxocara cati, from cats. Although most infected individuals are asymptomatic, clinical manifestations may include fever, fatigue, coughing, wheezing, or abdominal pain (visceral toxocariasis) or vision loss, retina damage, or eye inflammation (ocular toxocariasis). To assess U.S. pediatrician knowledge of toxocariasis, we conducted an electronic survey of American Academy of Pediatrics members. Of the 2,684 respondents, 1,120 (47%) pediatricians correctly selected toxocariasis as the diagnosis in an unknown case presentation with findings typical for toxocariasis; overall 1,695 (85%) stated they were not confident that their knowledge of toxocariasis was current. This knowledge gap suggests a need for improved toxocariasis awareness and education for U.S. pediatricians, especially those caring for children at risk for infection.

PEDIATRIC OCULAR TOXOCARIASIS IN JIANGSU PROVINCE, EASTERN CHINA.

Ocular toxocariasis is caused by migration of a Toxocara larva through the posterior eye. We report the first case of pediatric ocular toxocariasis caused by T. canis in Jiangsu Province, eastern China. A 6-year-old girl presented to Suzhou Municipal Children's Hospital with a complaint of right eye redness, minimal white discharge, no photophobia, eye pain, visual impairment, fever or arthralgia. She was initially diagnosed as having conjunctivitis; however, a 2-month treatment with lomefloxacin 0.3% eye drops gave no improvements. The diagnosis was made based on medical history (contact with dogs), clinical features and detection of T. canis IgG antibodies with an enzyme-linked immunosorbent assay (ELISA). Anthelmintic therapy with albendazole in combination with prednisolone resulted in improvement of the ocular symptoms. Ocular toxocariasis is rarely reported in China. However, the rapid economic development in China, could mean an increase in pet dogs with the potential increased risk of contracting toxocariasis if no control measures are taken. Disposal of pet litter, deworming of infected pets, complete cooking of meats, thorough rinsing of fruits and vegetables, and good hand-washing may help prevent human infections. Ocular toxocariasis should be considered in the differential diagnosis of patients with conjunctivitis that does not resolve with treatment.

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.

Potential immunological markers for diagnosis and therapeutic assessment of toxocariasis / Estudo de marcadores imunológicos para o diagnóstico e avaliação terapêutica da toxocaríase

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 percent for IgG antibodies to bands of molecular weight 29-38, 48-54, 95-116, 121-162, >205 kDa, 80.8 percent for IgE to 29-38, 48-54, 95-121, > 205 kDa, and 65.4 percent 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.

Métodos imunológicos desempenham papel importante no diagnóstico da toxocaríase, entretanto há poucos estudos sobre marcadores diagnósticos e de acompanhamento terapêutico. Foi padronizado ensaio de immunoblot (IB) empregando antígeno de excreção-secreção de Toxocara canis para pesquisa de anticorpos IgG, IgE e IgA em 27 crianças com toxocaríase nas formas visceral (23), mista visceral e ocular (3) e ocular (1), por 22-116 meses após quimioterapia. Foram observados dois perfis de reatividade dos anticorpos: permanência contra todas as frações no decorrer do estudo; diminuição ou negativação contra algumas ou todas as frações, porém, essas mudanças não se correlacionaram com tempo de tratamento. A sensibilidade do IB foi 100,0 por cento para anticorpos IgG específicos para frações de massa molecular de 29-38, 48-54, 95-116, 121-162, > 205 kDa, 80,8 por cento para IgE específicos para 29-38, 48-54, 95-121, > 205 kDa e 65,4 por cento para IgA específicos para 29-38, 48-54, 81-93 kDa. Anticorpos IgG específicos para frações de baixa MM (29-38 e 48-54 kDa) podem ser sugeridos como candidatos a marcadores diagnósticos. Por sua vez, anticorpos IgG para fração > 205 kDa, IgA para 29-38, 48-54, 81-93 kDa e IgE para 95-121 kDa podem ser candidatos a marcadores terapêuticos. A identificação de epítopos antigênicos relacionados a estes marcadores poderá ser importante para o desenvolvimento de ensaios altamente sensíveis e específicos no diagnóstico e avaliação terapêutica da toxocaríase.

Comparative assessment of enzyme-linked immunosorbent assay and Western blot for the diagnosis of toxocariasis in patients with skin disorders.

Background The link between various chronic skin disorders and toxocariasis was previously demonstrated by case reports and several case-control studies. However, these previous studies were based only on the Toxocara canis excretory-secretory-enzyme-linked immunosorbent assay (TES-ELISA) serological technique, which is not specific due to cross-reactivity with parasites of the genera Anisakis or Ascaris. Immunoblot analysis is highly specific and can detect very low levels of Toxocara antibodies. Therefore, this technique may be useful in the identification of Toxocara infection in patients with chronic skin disorders. Objectives Because urticaria and pruritus/prurigo are skin conditions previously associated with toxocariasis, we carried out a prospective study using both TES-ELISA and Toxocara Western blot on 113 patients with either chronic urticaria (n = 84) or chronic pruritus (n = 29). Methods Patients were matched with controls according to gender, age and residence location (rural or urban area). Data were analysed using a Mantel-Haenszel chi(2) test. Results The proportion of positive TES-ELISA results was not significantly different for patients with chronic skin disorders (urticaria or pruritus/prurigo) from that of control subjects. However, the proportion of positive immunoblot results was significantly higher for patients with chronic urticaria than for control subjects (P = 0.009). Conclusions Our study demonstrates the need to perform Western blotting immunodiagnosis, whatever the TES-ELISA result, to improve diagnosis of human toxocariasis in patients with chronic urticaria caused by Toxocara infection.