Search

Field studies have suggested an immune-mediated mechanism associated with resistance to Schistosoma mansoni infection. Overall, levels of specific IgE have been correlated with resistance to infection, whereas levels of IgG4 have been associated with susceptibility. This study aimed to evaluate serum levels of soluble adult worm antigen preparation (SWAP)-specific IgE and IgG4 in relation to current infection in a large casuistic of individuals living in an endemic area of schistosomiasis in Bahia, Brazil. The prevalence of S. mansoni infection was 37·7% and the mean parasite burden was 55·4 (0-2100) epg/faeces. There was no significant difference in the levels of SWAP-specific IgE in individuals with different parasite burden, whereas high producers of parasite-specific IgG4 presented higher parasite burden when compared to low IgG4 producers. Additionally, S. mansoni parasite load was positively correlated with the levels of specific IgG4 or total IgE. No significant correlation was observed between parasite burden and SWAP-specific IgE. Nevertheless, SWAP-specific IgE/IgG4 ratio was higher in uninfected or lightly infected individuals (1-99 epg/faeces) than in heavily infected ones (≥400 epg/feces). These findings highlight the important role of IgE/IgG4 ratio in the resistance to infection, which could be useful for further studies in schistosomiasis vaccine candidates., (© 2012 Blackwell Publishing Ltd.)

Detailed knowledge of factors associated with resistance to Schistosoma mansoni infection in endemic areas might facilitate more effective schistosomiasis control. We conducted a cross-sectional study of persons resistant to schistosomiasis and found no association between socioeconomic status and resistance to infection. Mononuclear cells of resistant subjects produced higher levels of interleukin-5 (IL-5), IL-13 and interferon-γ upon stimulation with soluble egg antigen (SEA) compared with infected persons. When stimulated with Sm21.6 or Sm22.6, levels of IL-10 were higher in cell culture of resistant persons. Levels of IgE against soluble adult worm antigen (SWAP) and against interleukin-4-inducing principle from S. mansoni eggs (IPSE) and levels of IgG4 against SWAP, SEA, and Sm22.6 were lower in the resistant group compared with the susceptible group. Our data suggest that socioeconomic status could not fully explain resistance to S. mansoni infection observed in the studied area. However, a mixture of Th1 and Th2 immune responses and low levels of specific IgG4 against parasite antigens could be mediating resistance to infection.

We studied the species composition of the snake community of Serra do Mendanha, in Rio de Janeiro state, Southeastern Brazil, with an effort of 800 hours/man in different habitats, including undisturbed forest, secondary forest, areas under regeneration, and banana plantation. We sampled snakes monthly in the area using a combination of methods including intensive visual searching and pitfall traps with drift-fences. We found a total of 191 individuals of 27 snake species, belonging to four families: Boidae, Colubridae, Elapidae and Viperidae. In terms of species richness, the most speciose snake family in the area was Colubridae (85.2%; n = 23), followed by Viperidae (7.4%; n = 2), Boidae (3.7%; n = 1) and Elapidae (3.7%; n = 1) (Table 1). Quantitatively, the family Colubridae represented 81.7% (n = 156) of the total of individuals captured throughout the study, followed by Elapidae (13.1% of the individuals; n = 25), Viperidae (4.7%; n = 9) and Boidae (0.5%; n = 1). The data obtained in the study allowed a first approximation of the richness and composition of the snake fauna from Serra do Mendanha, including the records obtained during fieldwork in the present study and those of specimens deposited in Institutional Collections and detailed field data for each voucher specimen. All records are novel data for the area.

Helminthic infections have been shown to inhibit allergy skin-prick tests and to modify the course of asthma. We evaluated Dermatophagoides pteronyssinus-specific immune responses in patients with asthma by measuring levels of T helper 2 (Th2) cytokines in peripheral blood mononuclear cell (PBMC) cultures. PBMCs from Schistosoma mansoni-infected patients with asthma living in an area of polyhelminthic endemicity produced lower levels of interleukin (IL)-5 and IL-4 in response to D. pteronyssinus antigen (Ag) 1 than did PBMCs from helminth-free patients with asthma. In contrast, D. pteronyssinus Ag 1-specific production of IL-10 was higher in helminth-infected patients than in helminth-free patients. The addition of recombinant human IL-10 to D. pteronyssinus Ag 1-stimulated cultures of PBMCs from helminth-free patients led to down-modulation of production of IL-5. After helminth-infected patients with asthma received antihelminthic treatment, there was down-modulation of D. pteronyssinus Ag 1-specific production of IL-10 in vitro. S. mansoni-infected patients with asthma produce lower levels of Th2 cytokines than do helminth-free patients with asthma, and this modulation is likely done by IL-10.

Background: Mite allergens have been involved in airway sensitization and allergic diseases. Immunoassays for the identification and quantifiction of house dust mite (HDM) allergens are useful to improve the knowledge of regional mite fauna and the remediation of mite allergens in allergic diseases. The present study analyzed the association between levels of HDM allergen and results of mite identification or skin prick test (SPT) in two different areas of Bahia, Brazil., Methods: Forty-two asthmatic subjects from a rural area (group I; n = 21) and a slum (group II; n = 21) were evaluated through SPT with HDM allergens and had dust samples collected at their homes for mite identification and allergen measurements., Results: Positive SPT to Dermatophagoides pteronyssinus, Dermatophagoides farinae and Blomia tropicalis allergens were observed in 42.9, 38.0 and 42.9% subjects from group I and in 47.6, 19.0 and 33.3% subjects from group II, respectively. D. pteronyssinus and B. tropicalis were identified in approximately 76 and 50% of samples from both groups, respectively. D. farinae was identified in 38.0 and 9.5% of samples from groups I and II, respectively (p < 0.005). Der p 1, Der f 1 and Blo t 5 detection were associated with mite identification (p < 0.05). Association between HDM allergen levels over 2 microg/g of dust and positive SPT occurred only with D. pteronyssinus (p < 0.0001)., Conclusions: D. pteronyssinus was the most prevalent mite species in this study followed by B. tropicalis and D. farinae. Immunoassays done to measure mite allergens were associated with mite-species identification. We conclude that these three mite species must be included on panels for the diagnosis of allergic airway diseases in subjects living in such regions., (Copyright 2002 S. Karger AG, Basel)