It is clear that leukotrienes mediate inflammatory response; new aspects of leukotriene function have recently been described. In this study, we demonstrate that leukotrienes are key chemical mediators in the control of parasite burdens in mice infected with Strongyloides venezuelensis. High leukotriene levels were detected in the lungs and small intestines of Swiss mice. In infected Swiss mice treated with MK886, a leukotriene synthesis inhibitor, numbers of adult worms, and eggs/g/feces were greater than in infected-only animals. The MK886 treatment inhibited leukotriene B4 production in the lungs and small intestines, albeit on different postinfection days. Similarly, parasite burdens and eggs/g/feces were greater in 5-lipoxygenase−/− mice than in wild-type animals. These observation were confirmed by histopathological study of the duodena. We subsequently observed significant lower numbers of eosinophils and mononuclear cells in the blood, peritoneal cavity fluid, and bronchoalveolar lavage fluid of Swiss mice treated with MK886. In the lung parenchyma of infected animals, MK886 significantly inhibited synthesis of IL-5 at the beginning of infection, whereas levels of IL-12 increased progressively throughout the postinfection period. However, levels of leukotriene C4, PGE2, TNF-α, IL-3, IL-4, IFN-γ, and IL-10 were comparable between the treated and untreated groups. Nevertheless, IgE and IgG1 (but not IgG2a) synthesis was also significantly inhibited by MK886 administration. Therefore, in S. venezuelensis-infected mice, adult worm and egg burdens are leukotriene dependent. These findings indicate potential immunostimulatory strategies involving leukotriene administration, and may serve as an alert to physicians treating Strongyloides stercoralis-infected patients presenting asthma-like symptoms because use of 5-lipoxygenase inhibitors may worsen the infection.
The present study was conducted to detected IgG antibodies using Strongyloides venezuelensis alkaline extract for the diagnosis of human strongyloidiasis by the enzyme-linked immunosorbent assay (ELISA). (Siddiqui & Berk 2001). Due to the fluctuations on the larvae shedding in subjects infected with S. stercoralis, the parasitological methods have shown low sensitivity, being necessary repeated stool exams (Dreyer et al. 1996, Uparanukraw et al. 1999. Complementary tests for the diagnosis and the monitoring of the immune response in this parasitosis have been developed. However, the major limitation for the standardization of immunological methods is the difficulty in obtaining large amount of S. stercoralis larvae (Sato et al. 1995, Costa-Cruz et al. 1997.The aim of this study was to diagnose human strongyloidiasis by enzyme-linked immunosorbent assay (ELISA) using alkaline extract of S. venezuelensis filariform larvae. The study received approval from the Ethical Committee of the Federal University of Uberlândia.Strain of S. venezuelensis was isolated from feces of the wild rodent Nectomys squamips in August 1988 and maintained by experimental infection in Rattus norvergicus-Wistar. Infective larvae of S. venezuelensis were obtained from the feces of rats experimentally infected and cultured in mineral charcoal for two days at room temperature. Larvae were recovered by the Rugai et al. (1954) method and washed five times in 0.01 M phosphatebuffered saline (PBS) pH 7.2 containing 400 IU/ml of benzyl penicilin and 2 mg/ml of streptomycin sulfate and then stored at -70 o C in PBS until the antigen preparation. Alkaline extract of 100,000 larvae of S. venezuelensis was prepared by adding 1 ml of 0.15 M NaOH (Merck, Germany) during 6 h under slow agitation at 4 o C. Subsequently, 0.5 ml of 0.3 M HCl (Merck) was added until reaching the pH 7.0, and this preparation was centrifuged at 10,000 g for 30 min at 4 o C. Protein determination of the supernatant was 240 µg/ml as detected by the Lowry et al. (1951) method.ELISA was carried out using polystyrene microplates (Difco, São Paulo, Brazil) and the reagents were assayed in 50 µl/well. The plates were coated with alkaline extract at 10 µg/ml in 0.06 M carbonate-bicarbonate buffer, pH 9.6 and incubated overnight at 4 o C. The plates were washed three times for 5 min with PBS containing 0.05% Tween 20 (PBS-T) and incubated with the serum samples, including positive and negative control sera, diluted at 1:80 in PBS-T for 45 min at 37 o C. After new washing as previously described, the conjugate rabbit anti-human IgG (Fc chain specific) labeled with peroxidase (Sigma, US) diluted at 1:2,000 in PBS-T was added and incubated for 45 min at 37 o C. After washing, the enzymatic substrate consisting of H 2 O 2 (Merck) plus o-phenylenediamine (OPD) diluted in 0.1 M citrate-Na 2 HPO 4 buffer pH 5.5 was added. The reaction was stopped after 15 min with 20 µl/well of 1 M H 2 SO 4 and the absorbance values were determined in an
The aim of this study was to determine the occurrence of intestinal parasites and commensals among children in four peripheral districts located in the northern, southern, eastern and western sectors of Uberlândia, Minas Gerais, using the Baermann methods as modified by Moraes and Lutz. Out of 160 individuals studied, 93 (58.1% CI: 50.4-65.7) were infected, distributed among the sectors as follows: northern (72.5%), southern (47.5%), eastern (57.5%) and western (55%). The positive findings according to age groups were: 0-5 years (26.9%), 5-10 years (21.2%) and 10-15 years (10%). Male children presented 2.7 times higher risk of infection than females did (OR: 2.7; CI: 1052-7001). The parasites and commensals identified were: Giardia lamblia (27.5%), Entamoeba coli (20.6%), Ascaris lumbricoides (14.4%), Enterobius vermicularis (8.8%), Hymenolepis nana (7.5%), Hymenolepis diminuta (5%), hookworms (3.1%), Trichuris trichiura (2.5%), Endolimax nana (2.5%), Entamoeba hartmanni (2.5%), Strongyloides stercoralis (1.3%), Iodamoeba butschlii (1.3%) and Capillaria hepatica (0.6%). The infection rate in these children was high and showed the need to implement prophylactic education programs in the community. Key-words:Enteroparasites. Commensals. Children. Epidemiology. Brazil. RESUMOO objetivo deste estudo foi determinar a ocorrência de parasitas e comensais intestinais em crianças de quatro bairros periféricos, localizados nos setores norte, sul, leste e oeste em Uberlândia, Minas Gerais, utilizando os métodos de Baermann modificado por Moraes, e de Lutz. Dos 160 indivíduos estudados, 93 (58,1%, IC: 50,4-65,7) estavam infectados, assim distribuídos: setor norte (72,5%), sul (47,5%), leste (57,5%) e oeste (55%). A positividade por faixa etária foi: 0 -5 anos (26,9%), 5 -10 (21,2%) e 10 -15 anos (10%). As crianças do sexo masculino mostraram 2,7 maior risco de infecção (OR: 2,7, IC: 1052-7001). Os agentes identificados foram: Giardia lamblia (27,5%), Entamoeba coli (20,6%), Ascaris lumbricoides (14,4%), Enterobius vermicularis (8,8%), Hymenolepis nana (7,5%), Hymenolepis diminuta (5%), ancilostomídeos (3,1%), Trichuris trichiura (2,5%), Endolimax nana (2,5%), Entamoeba hartmanni (2,5%), Strongyloides stercoralis (1,3%), Iodamoeba butschlii (1,3%) e Capillaria hepatica (0,6%). A porcentagem de infecção nas crianças foi alta e mostrou a necessidade de implantação de programas de educação profilática na comunidade.Palavras-chaves: Enteroparasitas. Comensais. Crianças. Epidemiologia. Brasil.
The aim of this study was to investigate the role of interleukin 12 (IL-12) during Strongyloides venezuelensis infection. IL-12(-/-) and wild-type C57BL/6 mice were subcutaneously infected with 1500 larvae of S. venezuelensis. On days 7, 14, and 21 post-infection, we determined eosinophil and mononuclear cell numbers in the blood and broncoalveolar lavage fluid (BALF), Th2 cytokine secretion in the lung parenchyma, and serum antibody levels. The numbers of eggs in the feces and worm parasites in the duodena were also quantified. The eosinophil and mononuclear cell counts and the concentrations of IL-3, IL-5, IL-10, IL-13, and IgG1 and IgE antibodies increased significantly in infected IL-12(-/-) and wild-type mice as compared with uninfected controls. However, the number of eosinophils and mononuclear cells in the blood and BALF and the Th2 cytokine levels in the lungs of infected IL-12(-/-) mice were greater than in infected wild-type C57BL/6 mice. In addition, serum IgE and IgG1 levels were also significantly enhanced in the infected mice lacking IL-12. Meanwhile, parasite burden and fecal egg counts were significantly decreased in infected IL-12(-/-) mice. Together, our results showed that the absence of IL-12 upregulates the Th2 immune response, which is important for control of S. venezuelensis infection.
The consumption of raw vegetables is related to health benefits. However, these foods might be source of foodborne diseases. The objective of the present study was to perform a microbiological and parasitological evaluation of the leafy vegetables commercially sold in five regions of Brazil at public wholesale markets. The 12 types of leafy vegetables (144 samples) were curly lettuce, looseleaf lettuce, red lettuce, chives, coriander, kale, basil, arugula, parsley, iceberg lettuce, chicory, and bean sprouts. The prevalences of total coliforms (88 to 100%) and thermotolerant coliforms (37 to 100%) were high, but Salmonella was not detected in any of the analyzed samples. All open markets sold vegetables contaminated with enteroparasites, mainly Entamoeba sp., Balantidium coli, Strongyloides sp., Ascaris sp., Enterobius vermicularis, and Ancylostomidae. Contamination was detected in all the regions (north, northeast, central west, southeast, and south) and types of vegetables, with higher prevalences in the northeast region, mainly in basil, lettuce, and chives. Contamination of vegetables by potentially pathogenic microorganisms is a national problem, and the distribution centers should improve quality control of these commercial vegetables. Considering the high frequency of enteroparasites and bacteria and the potential risk of disease transmitted by vegetables, we suggest greater enforcement of the sanitary surveillance of food offered to the public.
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