China
Africa
Explore chapters and articles related to this topic
The Parasite's Way of Life
Published in Eric S. Loker, Bruce V. Hofkin, Parasitology, 2023
Eric S. Loker, Bruce V. Hofkin
Some parasites relying on fecal–oral transmission have evolved adaptations in addition to resistant propagules that to some degree stack the deck in their favor by enhancing the likelihood of transmission. Cestodes, for instance, have indirect life cycles, and for many tapeworms, the adult host passes eggs in its feces that are subsequently consumed by the intermediate host. In some tapeworms using small aquatic crustaceans called ostracods as hosts, the tapeworm eggs appear similar to the aquatic algae on which the ostracod feeds, tricking the intermediate host into consuming them. Other tapeworms use copepods as intermediate hosts, and their eggs either sink or float, depending on whether or not the specific copepod in question is benthic or pelagic.
Surveillance and Control Programs for Cestode Diseases
Published in Max J. Miller, E. J. Love, Parasitic Diseases: Treatment and Control, 2020
Thirty cestode diseases of medical or veterinary importance have been identified. To attempt a comprehensive review of surveillance and control programs for all cestode diseases would be necessarily superficial, given the limitations of this chapter. Instead, this paper will review the current status of the two major forms of hydatid disease and the beef and pork tapeworms. I will try to place the public health impact of these infections into some perspective in relation to the achievements and prospects for success in controlling them.
An Overview of Helminthiasis
Published in Venkatesan Jayaprakash, Daniele Castagnolo, Yusuf Özkay, Medicinal Chemistry of Neglected and Tropical Diseases, 2019
Leyla Yurttaș, Betül Kaya Çavușoğlu, Derya Osmaniye, Ulviye Acar Çevik
Cestodes are a complex group of organisms, usually recognised as tapeworms, having a flat, ribbon-like white to yellowish body consisting of an anterior attachment organ (scolex) and a body (strobila) consisting of a chain of segments called proglottids. Proglottids are essentially packages of eggs which are regularly shed into the environment to infect other organisms. The width and length of tapeworms are different with some worms being several meters long (i.e., Diphyllobothrium latum is 2–15 m long, Taenids are 1–4 m long), while others can be very small (i.e., Hymenolepsis nana is 1.5–4 cm long, H. diminuta is 1–6 cm long) (Kotra and Dixit 2007).
The role of UDP-glycosyltransferases in xenobioticresistance
Published in Drug Metabolism Reviews, 2022
Diana Dimunová, Petra Matoušková, Radka Podlipná, Iva Boušová, Lenka Skálová
Helminths, parasitic worms such as cestodes, nematodes, and trematodes are a huge global health burden in humans, infecting hundreds of millions of people. In addition, helminth infections represent a common and often serious problem in veterinary medicine. Despite the widespread availability of anthelmintic therapy, the morbidity, and economic losses caused by helminths remain of great concern. Due to massive and inappropriate use of anthelmintics along with the limited types of this antiparasitic available for use, drug-resistant strains have developed in many helminths, thus anthelmintics have become less and less effective (Idris et al. 2019; Partridge et al. 2020). Due to the vastly increasing number of cases of helminth multi-resistance to all of the main classes of anthelmintics that have been reported, e.g. by Babjak et al. (2021), the mechanisms of drug-resistance in helminths have been intensively studied. Among these mechanisms, altered drug uptake as well as changes in drug metabolism have also attracted attention (Cvilink, Lamka, et al. 2009; Matouskova et al. 2016; Fairweather et al. 2020). Unfortunately, research has been focused mainly on cytochrome P450 enzymes and efflux transporters, while helminth UGTs have been neglected for a long time. At present, however, the importance of these UGTs is becoming clearer, specifically in nematodes.
Worm expulsion is independent of alterations in composition of the colonic bacteria that occur during experimental Hymenolepis diminuta-infection in mice
Published in Gut Microbes, 2020
Adam Shute, Arthur Wang, Timothy S. Jayme, Marc Strous, Kathy D. McCoy, Andre G. Buret, Derek M. McKay
The cestode, Hymenolepis diminuta, unlike many nematodes and trematodes, does not migrate through host tissues, and lacking hooks or abrasive structures it does no obvious damage to the small intestine. Lacking an alimentary track, H. diminuta worm absorbs nutrients across its tegument. H. diminuta successfully establishes in the permissive rat host but is expelled from mice via signal-transducer and activator of transcription (STAT)-6-mediated immunity.7 In rats, H. diminuta reduces the abundance of aerobic bacteria,8 and metagenomic analyses of rat cecal contents or feces revealed subtle changes in the microbiome with a putative bloom of Clostridiales.9–11 Infection with H. diminuta in wild mouse lemurs is associated with a reduction in specific orders of gut bacteria.12
Dibothriocephalus nihonkaiensis: an emerging concern in western countries?
Published in Expert Review of Anti-infective Therapy, 2019
Florence Robert-Gangneux, Brice Autier, Jean-Pierre Gangneux
By contrast, infection of fish with diphyllobothriid is more difficult to notice. First, the plerocercoid larvae of the cestode parasites are usually located in the muscle tissue of the fish, thus early eviscerating cannot get rid of it. Secondly, human infection is asymptomatic during weeks after consumption of the infected meal. It can remain so, or sometimes results in mild and non-specific gastrointestinal symptoms (diffuse abdominal discomfort, diarrhea or constipation) [7]. Thus, except when proglottids are released with feces, the disease is rarely suspected. Rare complications, e.g. intestinal obstruction or erratic migration [8], can occur, mainly in cases of massive infestation (the historically described megaloblastic anemia due to the capture of vitamin B12 by the parasite is practically exceptional nowadays and was more likely due to hostile life conditions in Europe after the war).