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The Ecology of Parasitism
Published in Eric S. Loker, Bruce V. Hofkin, Parasitology, 2023
Eric S. Loker, Bruce V. Hofkin
Just as the population biology of parasites is complex, so too are communities of parasites. Some host species are infected with many more parasite species than others for reasons discussed in the chapter. Although we have made progress in defining factors that influence the complexity of parasite communities, we have yet to fully grasp all the processes that dictate parasite community structure. In some cases though, it is clear that competitive hierarchies control the structure of parasite communities, giving us a way to predict parasite community structure. Human parasite communities are particularly intriguing, as our association with domesticated animals seems to have played a big role in influencing our parasite communities. Learning how different parasite species interact within an infected person is increasingly recognized as an important consideration in our efforts to control parasites. With respect to their role in food webs and ecosystems, recent studies suggest parasites play a far more prominent role than previously considered. For example, parasites often serve as prey for other species, may greatly influence the likelihood that the host in which they reside is eaten and in general increase the connectivity of ecosystems.
The Helminths
Published in Donald L. Price, Procedure Manual for the Diagnosis of Intestinal Parasites, 2017
There are five species of schistosomes that are considered to be human parasites, Schistosoma japonicum and S. mekongi in the Far East, S. mansoni in Africa and the Western Flemisphere, S. haematobium in Africa and the Middle East, and S. intercalatum in Africa. Members of the genus Schistosoma infecting man inhabit blood vessels of the extrahepatic portal and caval venous system, especially the mesenteric venules rich in nutrients coming from the intestine. Eggs laid by the female worms jam the small vessels adjacent to the intestinal and bladder wall. Some eggs are carried by the vessels to the liver and a lesser number to other organs. Other eggs, probably a majority, become trapped in or pass through the wall of the intestine (S. mansoni, S. japonicum, S. intercalatum) or bladder (S. haematobium). Those that reach the lumen of the intestine are evacuated with the feces and those that reach the lumen of the bladder are passed with the urine.
Filariasis
Published in F. Y. Liew, Vaccination Strategies of Tropical Diseases, 2017
Juliet A. Fuhrman, Willy F. Piessens
The first question requires individualized analysis of each host-parasite-vector group. At the simplest level, large animal reservoirs of human parasites, or wild animal reservoirs of parasites of veterinary importance, limit the practicality of transmission blocking immunity, particularly when the vectors involved are nonselective in their feeding habits. However, these concerns are not relevant to certain parasites of critical medical importance, such as W. bancrofti and O. volvulus, for which no animal reservoirs are known to exist. In the case of Onchocerca, Ivermectin treatment of infected humans dramatically decreased the level of infection in vectors fed on these patients. This effect lasted for at least 6 months after treatment.104 Immune intervention could potentially augment this effect, and such an approach could diminish the selection pressure for drug-resistant parasites and/or insecticide- resistant vectors.
Use of genetically modified lactic acid bacteria and bifidobacteria as live delivery vectors for human and animal health
Published in Gut Microbes, 2022
Romina Levit, Naima G. Cortes-Perez, Alejandra de Moreno de Leblanc, Jade Loiseau, Anne Aucouturier, Philippe Langella, Jean Guy LeBlanc, Luis G. Bermúdez-Humarán
Leishmaniasis is a disease caused by more than 30 species of the Leishmania parasite and is transmitted by the female sandfly vector to humans.122 Different alternatives have been evaluated with the aim of developing a live oral vaccine for this human parasite. A strain of L. lactis co- expressing the protective Leishmania homologue of activated C kinase (LACK) and mouse IL-12 induced an antigen-specific mucosal immune response in protected mice.123 Another study used a GM strain of L. lactis to express the protein PpSP15 an immunogenic component of saliva from the sand fly Phlebotomus papatasi. The strain was evaluated to immunize mice and it was described the induction of a strong immune response with a long-term protection against Leishmania major.41
Demodex and eye disease
Published in Clinical and Experimental Optometry, 2021
In conclusion, although Demodex was discovered more than 175-years ago, it is only relatively recently that its role in ocular and dermatological diseases has been widely discussed. Studies on its morphology, genetic structure, pathogenicity and co‐morbidities have enhanced the diagnostic techniques and management options for Demodex‐related disorders. The role of Demodex in ocular disease should no longer be debated, as there is evidence that it can affect several tissues of the anterior surface of the eye including the lids, lashes, meibomian glands, the tear film and the cornea. Advancements in imaging techniques, immunology and genetic testing of Demodex are promising and should further our understanding of this common human parasite.
Contribution of Plasmodium immunomics: potential impact for serological testing and surveillance of malaria
Published in Expert Review of Proteomics, 2019
Kokouvi Kassegne, Eniola Michael Abe, Yan-Bing Cui, Shen-Bo Chen, Bin Xu, Wang-Ping Deng, Hai-Mo Shen, Yue Wang, Jun-Hu Chen, Xiao-Nong Zhou
The control and elimination strategy of malaria is also fundamentally dependent on sensitive and specific serological testing to treat both blood and liver stages malaria parasites, as well as a need for new surveillance tools which can evaluate epidemic statuses of the infection [33–35]. In the past, the identification of serological markers for malaria surveillance has been hampered by the limited availability of promising approaches [33,36]. With the advent of immunoproteomics, conventional techniques in immunology such as two-dimensional gel electrophoresis, western blotting, and enzyme-linked immunosorbent assay (ELISA), have given more insights on host immune responses to malaria antigens [37]. Recently, genomics, transcriptomics, and proteomics have undoubtedly boosted immunomics for the characterization of potential antigen targets of host immunity, important tools for serological testing. Protein array, an immunomics-based technology, has been well documented for its contribution in providing a better understanding of host-pathogen interactions – host humoral immune responses to malaria infections. High-throughput infusion cloning (IFC) of target genes, wheat germ cell-free (WGCF) protein expression in ex-vivo transcription and translation bilayer reaction systems, probing of proteins in a HTP manner with sera of malaria subjects, are key components that facilitate Plasmodium immunomics [38]. The approach has been shown to efficiently screen large amount of human parasite antigens, and has proven to be an innovative and promising tool for antigen discovery, and its effectiveness is unquestionable [36,39]. Plasmodium immunomics has intensively profiled host humoral immune responses to Pf [40–49], while its application in vivax malaria research has slowly advanced [43–46,48,50–57]. However, less or nothing is known about immunomics of knowlesi malaria, since the infection has been long considered as benign, and, only few blood stage antigens have been identified very recently using ELISA [58,59].