[Prevalence and risk factors of human infection by Toxocara canis in Salvador, State of Bahia, Brazil]. / Prevalência e fatores de risco da infecção humana por Toxocara canis em Salvador, Estado da Bahia.

INTRODUCTION: Larva migrans visceral is caused by Toxocara sp and has never been studied in Bahia. This work investigated the prevalence and risk factors for infection by Toxocara canis in individuals from Salvador, State of Bahia. METHODS: Three hundred and thirty-eight individuals were investigated for the presence of serum IgG anti-T. canis. RESULTS: IgG anti-T. canis was higher in individuals from lower social classes who had more contact with dogs and cats, indicating that these variables are factors risk for this infection. CONCLUSIONS: The prevalence of T. canis infection was high. The risk factors for this infection identified are in agreement with in the literature.

Prevalência e fatores de risco da infecção humana por Toxocara canis em Salvador, Estado da Bahia / Prevalence and risk factors of human infection by Toxocara canis in Salvador, State of Bahia, Brazil

INTRODUÇÃO: Larva migrans visceral é causada por Toxocara sp e nunca foi estudada na Bahia. Neste trabalho, investigou-se a prevalência e fatores de risco de infecção por Toxocara canis, em indivíduos de Salvador. MÉTODOS: Trezentos e trinta e oito indivíduos foram investigados para presença de anticorpos IgG séricos anti-T. canis. RESULTADOS: IgG anti-T. canis foi mais alta em indivíduos de classe social baixa com maior contato com cães e gatos, indicando que estas variáveis são fatores de risco para esta infecção. CONCLUSÕES: A prevalência de infecção por T. canis foi alta. Os fatores de risco desta infecção encontrados estão de acordo com a literatura.

INTRODUCTION: Larva migrans visceral is caused by Toxocara sp and has never been studied in Bahia. This work investigated the prevalence and risk factors for infection by Toxocara canis in individuals from Salvador, State of Bahia. METHODS: Three hundred and thirty-eight individuals were investigated for the presence of serum IgG anti-T. canis. RESULTS: IgG anti-T. canis was higher in individuals from lower social classes who had more contact with dogs and cats, indicating that these variables are factors risk for this infection. CONCLUSIONS: The prevalence of T. canis infection was high. The risk factors for this infection identified are in agreement with in the literature.

Respiratory allergy to Blomia tropicalis: immune response in four syngeneic mouse strains and assessment of a low allergen-dose, short-term experimental model.

BACKGROUND: The dust mite Blomia tropicalis is an important source of aeroallergens in tropical areas. Although a mouse model for B. tropicalis extract (BtE)-induced asthma has been described, no study comparing different mouse strains in this asthma model has been reported. The relevance and reproducibility of experimental animal models of allergy depends on the genetic background of the animal, the molecular composition of the allergen and the experimental protocol. OBJECTIVES: This work had two objectives. The first was to study the anti-B. tropicalis allergic responses in different mouse strains using a short-term model of respiratory allergy to BtE. This study included the comparison of the allergic responses elicited by BtE with those elicited by ovalbumin in mice of the strain that responded better to BtE sensitization. The second objective was to investigate whether the best responder mouse strain could be used in an experimental model of allergy employing relatively low BtE doses. METHODS: Groups of mice of four different syngeneic strains were sensitized subcutaneously with 100 microg of BtE on days 0 and 7 and challenged four times intranasally, at days 8, 10, 12, and 14, with 10 microg of BtE. A/J mice, that were the best responders to BtE sensitization, were used to compare the B. tropicalis-specific asthma experimental model with the conventional experimental model of ovalbumin (OVA)-specific asthma. A/J mice were also sensitized with a lower dose of BtE. RESULTS: Mice of all strains had lung inflammatory-cell infiltration and increased levels of anti-BtE IgE antibodies, but these responses were significantly more intense in A/J mice than in CBA/J, BALB/c or C57BL/6J mice. Immunization of A/J mice with BtE induced a more intense airway eosinophil influx, higher levels of total IgE, similar airway hyperreactivity to methacholine but less intense mucous production, and lower levels of specific IgE, IgG1 and IgG2 antibodies than sensitization with OVA. Finally, immunization with a relatively low BtE dose (10 microg per subcutaneous injection per mouse) was able to sensitize A/J mice, which were the best responders to high-dose BtE immunization, for the development of allergy-associated immune and lung inflammatory responses. CONCLUSIONS: The described short-term model of BtE-induced allergic lung disease is reproducible in different syngeneic mouse strains, and mice of the A/J strain was the most responsive to it. In addition, it was shown that OVA and BtE induce quantitatively different immune responses in A/J mice and that the experimental model can be set up with low amounts of BtE.

Asthma and rhinitis symptoms in individuals from different socioeconomic levels in a Brazilian city.

Allergy is considered to be caused by complex interactions between genetic and environmental factors. Socioeconomic status (SES) may be the most important environmental determinant of allergy because it determines the living environment, but few studies have addressed the causal role of SES in allergy. The aim of this study was to compare the prevalence of asthma and rhinitis symptoms in two SES groups in a Brazilian city. History of asthma and rhinitis symptoms was collected using the International Study of Asthma and Allergies in Childhood questionnaire. SES was determined by the Gallup method. Sera from subgroups of the individuals were used to determine total, anti-Dermatophagoides pteronyssinus and anti-Blomia tropicalis IgE. The prevalence of asthma and rhinitis symptoms was higher in the A and B (A&B) SES group than in the C, D, and E (C, D&E) SES group. Individuals with asthma and/or rhinitis were more frequently positive for anti-B. tropicalis and anti-D. pteronyssinus IgE than individuals without these symptoms. A positive association between total IgE levels and asthma and rhinitis symptoms was observed in the A&B SES group but not in the C, D&E SES group. Women reported more respiratory symptoms than men. These results revealed higher prevalence rates ofasthma and rhinitis symptoms in individuals with higher SES and may provide support for the hygiene hypothesis, which attributes the high prevalence of respiratory allergies observed in individuals from developed countries to a low exposure to pathogens. The observed higher prevalence of asthma and rhinitis symptoms in women than in men could be attributed to differences in the perception of these symptoms or in exposures to allergens and protective pathogens.

Dust mite species and allergen concentrations in beds of individuals belonging to different urban socioeconomic groups in Brazil.

BACKGROUND: Dermatophagoides pteronyssinus, Dermatophagoides farinae and Blomia tropicalis dust mites are among the most important agents of hypersensitivity reactions in human beings. However, a role of other mites in the etiology of these reactions has not yet been excluded. OBJECTIVES: To investigate the nature of the dust mite fauna and the presence of Der p 1 (allergen 1 of Dermatophagoides pteronyssinus) and Blo t 5 (allergen 5 of Blomia tropicalis) on beds used by individuals with different socioeconomic backgrounds in Salvador, a major Brazilian city and to investigate possible associations of mite frequencies and allergen levels with (a) season of the year, (b) housing characteristics, (c) bed cleaning behaviors that could affect mite densities, and (d) allergy history. METHODS: Dust samples were collected from 459 beds of 101 residences from two groups with different socioeconomic levels (hereafter called wealthy and poor groups) in the city of Salvador, Brazil, for the identification of mite species and determination of Der p 1 and Blo t 5 levels. History of allergy was collected using the ISAAC phase I questionnaire. RESULTS: Eighty nine percent of the beds analyzed harbored at least one mite species. B. tropicalis was found in 71.8%, D. pteronyssinus in 39.9%, Cheyletus sp. in 33.9%, and Gohieria fusca in 21.1% of the beds. B. tropicalis was found with a similar frequency in beds of the two socioeconomic groups; D. pteronyssinus was found more frequently in the beds of the wealthy than of the poor group, whereas the reverse was observed with G. fusca. The concentrations of Der p 1 and Blo t 5 allergens exceeded the cut-off for sensitization of 2 microg/g of dust in 94.0% and 69.3% of the wealthy and poor group beds, respectively. No associations were found between history of allergy and mite species or between history of allergy and the concentrations of mite allergens. CONCLUSIONS: The observation of B. tropicalis and D. pteronyssinus as the most frequently found mites is consistent with previous reports from tropical regions. The higher frequency of G. fusca in beds of individuals from the poor group than those from the wealthy group could be a consequence of different bed cleaning behaviors between the two groups.