Helminth

Parasitic infections of rodents can compromise scientific research as well as the health of the animals and humans. Based on previous studies, infection rate of parasitic helminths is different in various regions of Iran. The current survey was aimed to determine endoparasitic helminths infection in 138 trapped rodents of Kermanshah county, Iran. Mice and rats were trapped using metal snares from January to October 2011 and euthanized. Rodents included 110 Mus musculus (79.00%), 23 Rattus norvegicus (17.00%), and five Rattus rattus (4.00%). The gastrointestinal and respiratory tracts were removed and examined to identify parasitic helminths. The results indicated that 42.02% of examined rodents were infected with eight helminths species, i.e. Trichuris muris (14.49%), Syphacia obvelata (13.76%), Syphacia muris (2.89%), Aspicularis tetrapetra (5.07%), Heterakis spumosa (5.07%), Capillaria hepatica eggs (3.62%), Hyminolepis diminuta (12.30%), and Cystisercus fasciolaris, the larva of ...

SUMMARYRNA interference (RNAi) has become an invaluable tool for the functional analysis of genes in a wide variety of organisms including the free-living nematode Caenorhabditis elegans. Recently, attempts have been made to apply this technology to parasitic helminths of animals and plants with variable success. Gene knockdown has been reported for Schistosoma mansoni by soaking or electroporating different life-stages in dsRNA. Similar approaches have been tested on parasitic nematodes which clearly showed that, under certain conditions, it was possible to interfere with gene expression. However, despite these successes, the current utility of this technology in parasite research is questionable. First, problems have arisen with the specificity of RNAi. Treatment of the parasites with dsRNA resulted, in many cases, in non-specific effects. Second, the current RNAi methods have a limited efficiency and effects are sometimes difficult to reproduce. This was especially the case in st...

The prevalence of autoimmune and allergic disorders has dramatically increased in developed countries, and it is believed that our 'cleaner living' reduces exposure to certain microorganisms and leads to deviated and/or reduced regulation of the immune system. In substantiation of this health hygiene hypothesis, multiple epidemiological studies and animal models have characterized the protective immune responses induced by helminths during auto-inflammatory disorders. The beneficial effects of such helminths, like schistosomes and filariae, are thought to lie in their immunomodulatory capacity, which can be induced by different life-cycle stages or components thereof. In addition to suppressing autoimmunity recent evidence indicates that concurrent helminth infections also counterbalance exacerbated pro-inflammatory immune responses that occur during sepsis, improving survival. As with allergy, epidemiological studies have observed a steady rise in severe sepsis cases and al...

The prevalence of autoimmune and allergic disorders has dramatically increased in developed countries, and it is believed that our 'cleaner living' reduces exposure to certain microorganisms and leads to deviated and/or reduced regulation of the immune system. In substantiation of this health hygiene hypothesis, multiple epidemiological studies and animal models have characterized the protective immune responses induced by helminths during auto-inflammatory disorders. The beneficial effects of such helminths, like schistosomes and filariae, are thought to lie in their immunomodulatory capacity, which can be induced by different life-cycle stages or components thereof. In addition to suppressing autoimmunity recent evidence indicates that concurrent helminth infections also counterbalance exacerbated pro-inflammatory immune responses that occur during sepsis, improving survival. As with allergy, epidemiological studies have observed a steady rise in severe sepsis cases and al...

The ribosomal RNA genes (rDNA) of Rhynchosciara americana were analysed using Southern transfers of DNA cleaved with EcoRI, HindIII, BamHI and PstI. The results show that the rDNA is heterogeneous in structure. Following digestion with EcoRI and hybridization to rRNA three bands corresponding to fragments of 9.5, 7.5 and 5.5 kilobases (kb) were detected. Recombinants containing EcoRI fragments of R. americana DNA were prepared using the vector λgtλB. Three different recombinants (λgtRa1, λgtRa23 and λgtRa5) were isolated containing the rDNA fragments of 9.5, 7.5 and 5.5 kb, respectively. These fragments were transferred to pBR325 and analysed with restriction enzymes and Southern hybridization with 28 S and 18 S rRNA. The λgt recombinants were further analysed by R-loop mapping. The data show that the rDNA occurs in two different repeating gene units. A shorter repeat of 9.5 kb and a longer repeat of 13 kb, in which the 28 S rRNA coding sequence contains an insertion of 3.5 kb.

IgG4 has been proposed to act as a 'blocking antibody' due to its ability to compete for the same epitopes as IgE thus preventing IgE-dependent allergic responses. IgG4 and IgE are both elevated in helminth infections and strong anti-parasite IgE responses are associated with resistance to infection. We wished to determine the relationship between anti-parasite IgG4 and IgE and Ascaris lumbricoides infection status. We examined anti-parasite responses, including antibody levels to recombinant Ascaris allergen-1A (rABA-1A), a target of serum IgE in endemic populations. Worm burden was indirectly estimated by measuring parasite egg output in a cross-sectional human population (N = 105). Levels of anti-parasite IgG4 and IgE in patients' plasma were quantified by immunoassay. Global anti-parasite antibody responses did not bear any significant relationships with intensity of Ascaris infection. Individuals who had detectable levels of IgE but not IgG4 to rABA-1A (11%) had lower average levels of infection compared with individuals who produced anti-rABA-1A IgG4 (40%) and sero-negative individuals (49%) (P = 0.008). The ratio of IgG4/IgE in rABA-1A responders positively correlated with intensity of infection (P < 0.025). IgG4 levels positively correlated with infection level in younger children (age 4-11) where average levels of infection were increasing (P = 0.038), whereas allergen specific IgE emerged as a correlate of immunity in older children and adults (age 12-36) where infection levels were decreasing (P = 0.048). Therefore, in a gastrointestinal helminth infection, differential regulation of anti-allergen antibody isotypes relate to infection level. Our results are consistent with the concept that IgG4 antibody can block IgE-mediated immunity and therefore allergic processes in humans.

Parasitic infections of rodents can compromise scientific research as well as the health of the animals and humans. Based on previous studies, infection rate of parasitic helminths is different in various regions of Iran. The current survey was aimed to determine endoparasitic helminths infection in 138 trapped rodents of Kermanshah county, Iran. Mice and rats were trapped using metal snares from January to October 2011 and euthanized. Rodents included 110 Mus musculus (79.00%), 23 Rattus norvegicus (17.00%), and five Rattus rattus (4.00%). The gastrointestinal and respiratory tracts were removed and examined to identify parasitic helminths. The results indicated that 42.02% of examined rodents were infected with eight helminths species, i.e. Trichuris muris (14.49%), Syphacia obvelata (13.76%), Syphacia muris (2.89%), Aspicularis tetrapetra (5.07%), Heterakis spumosa (5.07%), Capillaria hepatica eggs (3.62%), Hyminolepis diminuta (12.30%), and Cystisercus fasciolaris, the larva of ...

Here we analyze patterns of human infection with Onchocerca volvulus (the cause of river blindness) in different continents and ecologies. In contrast with some geohelminths and schistosome parasites whose worm burdens typically exhibit a humped pattern with host age, patterns ...

The whipworm of the genus Trichuris Roederer, 1791, is a nematode of worldwide distribution and comprises species that parasitize humans and other mammals. Infections caused by Trichuris spp. in mammals can lead to various intestinal diseases of human and veterinary interest. The morphology of Trichuris spp. and other helminths has been mostly studied using conventional scanning electron microscopy of chemically fixed, dried and metal-coated specimens, although this kind of preparation has been shown to introduce a variety of artifacts such as sample shrinking, loss of secreted products and/or hiding of small structures due to sample coating. Low vacuum (LVSEM) and environmental scanning electron microscopy (ESEM) have been applied to a variety of insulator samples, also used in the visualization of hydrated and/or live specimens in their native state. In the present work, we used LVSEM and ESEM to analyze the surface of T. muris and analyze its interaction with the host tissue usin...

Strongyloides venezuelensis migrates through the lungs and induces airway hyperresponsiveness (AHR). The present study evaluated the role of C-fibers in mediating airway inflammation and AHR after infection of rats with S. venezuelensis. Neonatal treatment with capsaicin effectively depleted sensory nerves. This was accompanied by inhibition of the AHR induced by S. venezuelensis infection. In contrast, capsaicin treatment greatly enhanced pulmonary inflammation, eosinophil influx and the local production of TNF-alpha. In conclusion, this is the first demonstration that, akin to viral and allergic AHR, permanent loss of sensory nerve C-fibers also reduces AHR induced by infection with a helminth.

Malaria and helminth infections have a shared geographical distribution and therefore co-infections are frequent in tropical areas of the world. Human populations of helminth and malaria co-infection have shown contradictory results for the course of malarial infection and disease, possibly depending on the type of helminth studied, the intensity of helminth infection and the age of the study population. Although immunological studies might clarify the underlying mechanisms of protection or increased susceptibility, there are very few studies that have looked at immunological parameters in helminth and malaria co-infection. After discussing the available immunological data on co-infection, we describe a pilot study performed in Ghanaian school children where we compare anti-malarial responses in children living in an urban area, where the prevalence of helminth and Plasmodium falciparum infections was low, with that of children living in a rural area with high prevalence of helminth and Plasmodium falciparum infections.

A gnatostomíase é parasitose endêmica em alguns países asiáticos, causada pela ingestão da larva do nematódio Gnathostoma sp, que pode ocorrer no consumo de carne crua de peixes de água doce. Atinge vários órgãos, entre eles a pele, manifestando-se frequentemente como lesão subcutânea migratória. Países da América Central e do Sul como México e Peru vêm apresentando número crescente de casos da doença desde 1970. Este trabalho registra o primeiro caso notificado e publicado no Brasil e alerta para o surgimento dessa doença em áreas anteriormente não endêmicas. Relata-se caso de paciente, com história de viagem ao Peru, que evoluiu com quadro cutâneo compatível com gnatostomíase.

Inflammatory bowel disease (IBD) is prevalent in industrialized countries, but rare in less-developed countries. Helminths, common in less-developed countries, may induce immunoregulatory circuits protective against IBD. IL-10–/– mice given piroxicam develop severe and persistent colitis. Lamina propria mononuclear cells from colitic IL-10–/– mice released IFN-γ and IL-12. The ongoing piroxicam-induced colitis could be partially blocked with anti-IL-12 monoclonal antibody suggesting that the inflammation was at least partly IL-12 dependent. Colonization of piroxicam-treated colitic IL-10–/– mice with Heligmosomoides polygyrus (an intestinal helminth) suppressed established inflammation and inhibited mucosal IL-12 and IFN-γ production. H. polygyrus augmented mucosal IL-13, but not IL-4 or IL-5 production. Transfer of mesenteric lymph node (MLN) T cells from IL-10–/– animals harboring H. polygyrus into colitic IL-10–/– recipients inhibited colitis. MLN T cells from worm-free mice did not. Foxp3 (scurfin) drives regulatory T cell function. H. polygyrus enhanced Foxp3 mRNA expression in MLN T cells that had regulatory activity. This suggests that H. polygyrus inhibits ongoing IL-10–/– colitis in part through blocking mucosal Th1 cytokine production. Resolution of inflammation is associated with increased IL-13 production and can be adoptively transferred by MLN T cells.

Every year populations of the European woodcock (Scolopax rusticola) migrate from Central and Northern Europe to the Mediterranean basin. South of Italy is one of the most common wintering site for this species. Given that information on parasites of woodcocks is scarce, the present study aimed at identifying the parasitic species affecting woodcocks migrating in Italy. The gastrointestinal tract of 206 woodcocks hunted in Southern Italy was removed and examined for parasites. From each animal a faecal sample was analysed by flotation test. The necropsy showed the presence of cestodes, i.e. Paricterotaenia paradoxa (59.4%) and Aploparaksis filum (49.5%), and of acanthocephalan Prosthorhynchus scolopacidis (22.4%). In one bird we also detected Parastrigea robusta, which is a trematode until now reported only in mallards (Anas platyrhynchos). Mixed infections (i.e., polyspecific infections) were detected in 53 (27.6%) animals. The most common were those caused by A. filum and P. paradoxa (12.5%), and by P. paradoxa and P. scolopacidis (8.3%). Copromicroscopic examinations revealed the presence of eggs belonging to nematodes Syngamus spp. (1.94%) in 4 woodcocks and of eggs of cestodes Aploparaksis spp. (37.86%) in 78 woodcocks. The present results fill a gap in the knowledge on parasites affecting woodcocks.