Immunological Mechanisms by Which Concomitant Helminth Infections Predispose to the Development of Human Tuberculosis

Helminthic infections afflict over 1.5 billion people worldwide, while Mycobacterium tuberculosis infects one third of the world's population, resulting in 2 million deaths per year. Although tuberculosis and helminthic infections coexist in many parts of the world, and it has been demonstrated that the T-helper 2 and T-regulatory cell responses elicited by helminths can affect the ability of the host to control mycobacterial infection, it is still unclear whether helminth infections in fact affect tuberculosis disease. In this review article, current progress in the knowledge about the immunomodulation induced by helminths to diminish the protective immune responses to bacille Calmette-Guerin vaccination is reviewed, and the knowledge about the types of immune responses modulated by helminths and the consequences for tuberculosis are summarized. In addition, recent data supporting the significant reduction of both M. tuberculosis antigen-specific Toll-like receptor (TLR) 2 and TLR9 expression, and pro-inflammatory cytokine responses to TLR2 and TLR9 ligands in individuals with M. tuberculosis and helminth co-infection were discussed. This examination will allow to improve understanding of the immune responses to mycobacterial infection and also be of great relevance in combating human tuberculosis.

Resistência anti-helmíntica de nematóides gastrintestinais em ovinos, Mato Grosso do Sul / Anthelmintic resistance of gastrointestinal nematodes in sheep, Mato Grosso do Sul, Brazil

Entre os métodos de controle da verminose gastrintestinal em ovinos, a utilização de produtos químicos é o mais empregado. Porém, o uso indiscriminado e continuado desses produtos tem selecionado populações de helmintos resistentes aos anti-helmínticos, fenômeno relatado no mundo todo. Este trabalho teve como objetivo identificar as espécies de parasitos gastrintestinais e diagnosticar a situação da resistência anti-helmíntica em ovinos no Estado de Mato Grosso do Sul. Foram realizados testes de redução na contagem de ovos por grama de fezes (OPG) em rebanhos de dezesseis propriedades rurais; as sete formulações utilizadas continham as seguintes bases farmacológicas: Albendazol, Ivermectina, Levamisole, Triclorfon, Moxidectina, Closantel e uma contendo as três primeiras associadas. As espécies identificadas nas necropsias, em ovinos adultos, foram: Haemonchus contortus, Trichostrongylus colubriformis, Cooperia curticei, C. punctata, C. pectinata e Oesophagostomum columbianum; em ordem de prevalência. As formulações contendo Albendazol e Ivermectina não apresentaram eficácia na redução de OPG nos rebanhos testados, com médias de redução de 0,7 e -19,6 por cento, respectivamente. Closantel apresentou eficácia média de 6,7 por cento; Levamisole, Moxidectina e Triclorfon de 28,7, 26,8 e 65 por cento, respectivamente; a associação das três bases (Albendazol, Ivermectina e Levamisole), uma média de eficácia de 55,8 por cento. As percentagens médias de larvas infectantes recuperadas nas coproculturas, tanto no pré como no pós-tratamento, foram semelhantes; indicando que a resistência às bases testadas está presente em todas as espécies citadas, em maior ou menor intensidade. Os dois gêneros predominantemente resistentes são Haemonchus sp., com 86,9 por cento; seguido por Trichostrongylus sp., com média de 47,5 por cento; Strongyloides sp. 33,6 por cento; Oesophagostomum, sp. 21,4 por cento e Cooperia sp. 19,7 por cento.

Among the methods of control of gastrointestinal worms in sheep, the use of chemicals is the most common. However, the continued, and indiscriminate, use of these products has selected populations of resistant helminths to anthelmintics, a phenomenon reported in the whole world. This study aimed to identify the species of gastrointestinal parasites and diagnose the status of anthelmintic resistance in sheep in the State of Mato Grosso do Sul Brazil. Feacal egg count reduction tests (FECRT) were performed in flocks of sixteen farms, and the seven formulations used contained the following pharmacological bases: Albendazole, Ivermectin, Levamizol, Trichlorfon, Moxidectin, Closantel and one containing the first three in association. The species identified at necropsy, in adult sheep, were: Haemonchus contortus, Trichostrongylus colubriformis, Cooperia curticei, C. punctata, C. pectinata and Oesophagostomum columbianum, in order of prevalence. The formulations containing Albendazole and Ivermectin did not show efficacy in reducing the EPG in the flocks tested, with average reductions of 0.7 and -19.6 percent, respectively. Closantel presented an average efficacy of 6.7 percent; Levamisolee, Moxidectin and Trichlorfon, 28.7, 26.8 and 65 percent respectively, the combination of three bases (Albendazole, Ivermectin and Levamizol), an average efficacy of 55.8 percent. The average percentages of infective larvae recovered in the faecal cultures, pre and post treatment were similar, indicating that resistance to the bases tested is present in all species cited, to a greater or lesser degree. The two genera predominantly resistant are Haemonchus sp., with 86.9 percent, followed by Trichostrongylus sp., with an average of 47.5 percent, Strongyloides sp. 33.6 percent, Oesophagostomum sp. 21.4 percent and Cooperia sp. 19.7 percent.

Eosinophil-Mediated Tissue Inflammatory Responses in Helminth Infection

Eosinophilic leukocytes function in host protection against parasitic worms. In turn, helminthic parasites harbor specific molecules to evade or paralyze eosinophil-associated host immune responses; these molecules facilitate the migration and survival of parasitic helminths in vivo. This competition between eosinophil and worm leads to stable equilibria between them. An understanding of such dynamic host-eosinophil interactions will help us to uncover mechanisms of cross talk between host and parasite in helminth infection. In this review, we examine recent findings regarding the innate immune responses of eosinophils to helminthic parasites, and discuss the implications of these findings in terms of eosinophil-mediated tissue inflammation in helminth infection.

Thermostability of heterophile antibodies from human sera infected with Schistosoma mansoni and geo-helminths. an immuno-metric statistical analysis

Foram investigados anticorpos de soro humano que provocam lise de eritrócitos de carneiro em ensaios hemolíticos. O presente estudo mostra que a presença de anticorpos citolíticos termoestáveis contra hemácias de carneiro é dependente da infecção por Schistosoma mansoni e é mais freqüente em adultos do que em crianças. A característica termo estável da hemolisina em soros normais não é dependente da presença de Ascaris lumbricoides, Trichuris trichiura ou ancilostomídeos. Além disto, anticorpos heterófilos hemolíticos termo estáveis ativadores de complemento foram demonstrados em crianças com associação de altas cargas de ovos de S. mansoni. Os resultados foram obtidos usando-se os testes z- e o qui quadrado. O teste z- nos permite formular uma alternativa "one side", isto é, a tendência de um dos atributos. Por outro lado o teste do qui quadrado analisa a independência entre atributos usando-se uma tabela de contingência. Ao lado dos interessantes resultados obtidos no campo da esquistossomose mansoni, a abordagem estatística pode apontar novos caminhos para o tratamento de dados na ciência médica.

Immune responses of IL-5 transgenic mice to parasites and aeroallergens

Eosinophils have long been thought to be effectors of immunity to helminth but have also been implicated in the pathogenesis of asthma. Patterns of cytokine production in the host may influence the pathogenesis of these diseases by regulating the activities of eosinophils and other components of the immune response. Mice which constitutively over-express IL-5 have profound and life-long eosinophilia in a restricted number of tissues. Although eosinophils from IL-5 transgenics are funtionally competent for a number of parameters considered to be important in inflammation, untreated animals are overtly normal and free of disease. In addition, the responses of these animals when exposed to aeroallergens and helminth present a number of apparent paradoxes. Eosinophil accumulation in tissue adjacent to major airways is rapid and extensive in transgenics exposed to the aeroallergen, but even after treatment with antigen over many months these mice show no evidence of respiratory distress or pathology. Helminth-infected IL-5 transgenics and their non-transgenic littermates develop similar inflammatory responses at mucosal sites and are comparable for a number of T cell and antibody responses, but they differ considerably in their ability to clear some parasite species. The life-cycle of Nippostrongylus brasilensis is significantly inhibited in IL-5 transgenics, but that of Toxocara canis is not. Our results suggest that eosinophilia and/or over-expression of IL-5 may actually impair host resistance to Schistosoma mansoni and Trichinella spiralis. The pathogenesis of diseases in which eosinophils are involved may therefore be more complex than previously thought.

O papel protetor das infecçöes por helmintos / The protector role of helminths

O autor faz revisäo de trabalhos a respeito do papel das helmintoses nas alergopatias e indaga sobre as causas do aumento da incidência dos processos alérgicos na populaçäo urbana.

Alteraçöes pancreáticas em bovinos naturalmente infectados por Eurytrema spp e sua associaçäo com a carga parasitária e o número de ovos por grama de fezes (OPG) / Gradation of microscopic lesions in pacreas of Eurytrema spp naturally infected cattle and its relationship with the parasite load and number of eggs per gram of faeces (EPG)

Foram examinados, ao microscópio óptico, fragmentos de 41 pâncreas de bovinos naturalmente infectados por Eurytrema spp e as lesöes encontradas foram classificadas em quatro graus, de acordo com sua extensäo desde o epitélio dos ductos. Em seguida, tomando-se os valores das cargas parasitárias (CP) e o número de ovos por grama de fezes (OPG) dos animais, em cada grau de lesäo estabelecido, comprovou-se que os valores de OPG e, principalmente, da CP podem ser utilizados para caracterizar, de maneira satisfatória, a extensäo das lesöes pancreáticas

Immunodiagnosis in clinical practice.

Although the definitive diagnosis of diseases caused by worms and protozoa depends upon the demonstration of adult parasite or its ovum in excreta, blood and tissue biopsies of the patient, immunological methods can be of help in the identification of associated immunological syndromes, pathogeneses of these infections in man and as a guide to therapy. However, the non-availability of pure antigens is a limiting factor in effective application of these tests. The present paper describes the immunological syndromes associated with these diseases as well as some of the in-use immunodiagnostic tests.