Granuloma Formation during Parasitic Infections

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Granuloma Formation during Parasitic Infections Once parasites start an infection, they can effectively resist the lethal effects of macrophages and produce chronic infection that can lead to inflammation. Parasites can induce granulomatous inflammation that serves to insulate the pathogens that resist destruction (58). These granulomas are regulated by T cells that recognize parasite-released antigens. In the tissues macrophages accumulate and secrete chemicals that induce fibrosis and stimulate the formation of granulomatous tissue and provoke fibrosis. During infection with Schistosoma spp, granuloma formation around the eggs is developed (59) (see chapter 4). Several eggs are transported to the liver where they become insulated behind a capsule containing several different types of inflammatory cells (59). In experiments performed in mice, granuloma formation predominantly consists of eosinophils and is the result of a T cell-dependent reaction (59). In visceral leishmaniasis parasites spread into the liver, spleen, lymph nodes and bone marrow frequently occurs. This parasite-dissemination produces enlargement of the liver and the spleen in a condition known as hepatosplenomegaly, fever, abdominal pain and weight loss are some symptoms associated to this condition. The disease is fatal if untreated, because of many complications such as secondary infections, anemia and malnutrition (60). In visceral leishmaniasis, fever, pallor, weakness, night sweats, anorexia, and weight loss are common and progress to a medical condition known as cachexia (wasting syndrome), a general wasting condition associated to overproduction of TNF- (also known as cachexin). Children with visceral leishmaniasis can develop diarrhea and growth retard... ... middle of paper ... ...unity plays an important role in the development of gut pathology during experimental and human giardiasis. Once again, the uncontrolled response of this T cell immunity could be detrimental to the host by inducing collateral tissue damage. CONCLUSION Parasitic diseases constitute a major health problem worldwide, affecting mostly poor countries. The World Health Organization has targeted several parasitic diseases as the most important worldwide. These diseases include malaria, chagas disease, leishmaniasis, filariasis and schistosomiasis. Tissue damage and death induced by parasitic infections is produced specially after chronic infections and several organs are affected depending on the type of infection. Better understanding of the molecular mechanisms of these diseases will be useful to identify targets to develop therapeutic prototypes and vaccines.

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