Identification of Glycycometus malaysiensis (for the first time in Brazil), Blomia tropicalis and Dermatophagoides pteronyssinus through multiplex PCR.

Blomia tropicalis and Dermatophagoides pteronyssinus play an important role in triggering allergy. Glycycometus malaysiensis causes IgE reaction in sensitive people, but is rarely reported in domestic dust, because it is morphologically similar to B. tropicalis making the identification of these species difficult. The identification of mites is mostly based on morphology, a time-consuming and ambiguous approach. Herein, we describe a multiplex polymerase chain reaction (mPCR) assay based on ribosomal DNA capable to identify mixed cultures of B. tropicalis, D. pteronyssinus and G. malaysiensis, and/or to identify these species from environmental dust. For this, the internal transcribed spacer 2 (ITS2) regions, flanked by partial sequences of the 5.8S and 28S genes, were PCR-amplified, cloned and sequenced. The sequences obtained were aligned with co-specific sequences available in the GenBank database for primer design and phylogenetic studies. Three pairs of primers were chosen to compose the mPCR assay, which was used to verify the frequency of different mites in house dust samples (n = 20) from homes of Salvador, Brazil. Blomia tropicalis was the most frequent, found in 95% of the samples, followed by G. malaysiensis (70%) and D. pteronyssinus (60%). Besides reporting for the first time the occurrence of G. malaysiensis in Brazil, our results confirm the good resolution of the ITS2 region for mite identification. Furthermore, the mPCR assay proved to be a fast and reliable tool for identifying these mites in mixed cultures and could be applied in future epidemiological studies, and for quality control of mite extract production for general use.

A prospective seroepidemiological study of toxocariasis during early childhood in coastal Ecuador: potential for congenital transmission and risk factors for infection.

BACKGROUND: Although Toxocara spp. infection has a worldwide distribution, to our knowledge, no data from birth cohorts have been reported in published studies on the potential for congenital transmission and determinants of infection in early childhood. METHODS: We followed 290 mother-infant pairs from birth to 5 years of age through periodic collection of data and samples at birth, 7 and 13 months and 2, 3 and 5 years of age. Data on potential risk factors and confounders were collected by maternal questionnaire. Blood for plasma was collected from the mother at time of birth and periodically from the child for detection of anti-Toxocara spp. immunoglobulin G (IgG) antibodies using a Toxocara canis larval excretory-secretory antigen-based enzyme-linked immunosorbent assay. Stool samples were collected from the mother around the time of birth and periodically from the child for microscopic detection of soil-transmitted helminths (STH). Associations between potential risk factors and Toxocara spp. seroprevalence and seroconversion were estimated using multivariable logistic regression and generalized estimating equations. RESULTS: Toxocara spp. seroprevalence was 80.7% in mothers and in children was 0%, 9.3%, 48.4%, 64.9%, and 80.9% at 7 months, 13 months, 2, 3 and 5 years, respectively. Risk factors significantly associated with increases in seroprevalence over the first 5 years of life in multivariable analyses were age [Odds ratio (OR) 2.06, 95% confidence interval (CI) 1.39-2.27, P < 0001], male sex (female vs. male: OR 0.66, 95% CI 0.48-0.89, P = 0.006), maternal ethnicity (non-Afro vs. Afro-Ecuadorian: OR 0.65, 95% CI 0.47-0.91, P = 0.011), lower maternal educational and socioeconomic level, and childhood STH (OR 2.29, 95% CI 1.51-3.47, P < 0.001). Seroconversion rates for infection were greatest at 2 years of age (3.8%/month). Factors associated significantly with seroconversion at 2, 3 or 5 years were childhood STH infection, male sex, and more frequent domestic cat exposure. CONCLUSIONS: Our data, from an area of high Toxocara spp. endemicity, indicate no congenital transmission but high rates of seroconversion after 13 months of age reaching maternal levels of seroprevalence by 5 years of age. Factors associated with seroprevalence and seroconversion included STH infections, domestic cats, maternal ethnicity, male sex, STH infections, and markers of greater poverty.

Toxocariasis and Toxocara vaccine: a review / Toxocariasis y vacunación para Toxocara: una revisión sistemática / Toxocaríase e vacina para controle de Toxocara: uma revisão

Abstract Based on prevalence and impact on public health, toxocariasis is an underestimated zoonosis in developing and developed countries. The transmission of Toxocara spp. involves pets, stray dogs and cats (Canis familiaris and Felis catus, respectively), which spread the parasite's eggs in their feces to the environment. One of the main risk factors for the infection and development of human toxocariasis, is to cohabit with puppies and kittens. For a long time, the preventive strategy for this parasitic infection has been the regular use of antiparasitic drugs to reduce parasite burden in the short term. A long lasting immunological protection can be achieved with vaccination, however, a vaccine is not yet available. Therefore, it is fundamental to know and to understand the state of the art of vaccine development for effective control of this zoonosis. This paper reviews the experimental studies focused on vaccine development for toxocariasis control, and special attention is given to relevant epidemiological studies on the importance of dogs in human toxocariasis.

Resumen Según la prevalencia y el impacto en la salud pública, la toxocariasis es una zoonosis subestimada en los países en desarrollo y desarrollados. La transmisión de Toxocara spp. involucra animales de compañía caninos y felinos, como también perros y gatos sin hogar (Canis familiaris y Felis catus, respectivamente), que diseminan los huevos del parásito en sus heces al medio ambiente. Uno de los principales factores de riesgo para la infección y el desarrollo de la toxocariasis humana es convivir con cachorros felinos y caninos. Durante mucho tiempo, la estrategia preventiva para esta infección parasitaria ha sido el uso regular de medicamentos antiparasitarios para reducir la carga parasitaria a corto plazo. Se puede lograr una protección inmunológica duradera con la vacunación, sin embargo, todavía no se dispone de una vacuna. Por lo tanto, es fundamental conocer y comprender el estado del arte del desarrollo de vacunas para el control efectivo de esta zoonosis. Este artículo revisa los estudios experimentales centrados en el desarrollo de vacunas para el control de la toxocariasis, y se presta especial atención a los estudios epidemiológicos relevantes sobre la importancia de los caninos domésticos en la toxocariasis humana.

Resumo Com base na prevalência e no impacto na saúde pública, a toxocaríase é uma zoonose subestimada nos países em desenvolvimento e desenvolvidos. A transmissão de Toxocara spp. envolve animais cães e gatos de estimação e vadios (Canis familiaris e Felis catus, respectivamente), que espalham os ovos do parasita nas fezes para o meio ambiente. Um dos principais fatores de risco para a infecção e desenvolvimento da toxocaríase humana é coabitar com filhotes de cachorros e gatos. Por um longo tempo, a estratégia preventiva para essa infecção parasitária tem sido o uso regular de medicamentos antiparasitários para reduzir a carga parasitária a curto prazo. Uma proteção imunológica duradoura pode ser alcançada com a vacinação, no entanto, uma vacina ainda não está disponível. Portanto, é fundamental conhecer e entender o estado da arte do desenvolvimento de vacinas para o controle efetivo dessa zoonose. Este artigo revisa os estudos experimentais focados no desenvolvimento de vacinas para o controle da toxocaríase, e atenção especial é dada a estudos epidemiológicos relevantes sobre a importância dos cães na toxocaríase humana.