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The Parasite's Way of Life
Published in Eric S. Loker, Bruce V. Hofkin, Parasitology, 2023
Eric S. Loker, Bruce V. Hofkin
Such transmission, fecal–oral alternating with trophic, is typical of cestodes as well as many other parasites with indirect life cycles. Hymenolepis diminuta, the rat tapeworm, provides a representative example (Figure 3.11). Various insects that serve as intermediate hosts may consume eggs passed in a rat’s feces. The eggs hatch in the insect’s digestive system, releasing a larval stage known as an oncosphere. The oncosphere penetrates the insect’s gut wall and enters the body cavity, where it develops into a cysticercoid. Transmission back to the definitive host occurs when a rat consumes the infected insect. Human infections are uncommon, but they can occasionally occur if a human inadvertently consumes an infected insect. This is most likely when a flour beetle (genus Tribolium) is acting as an intermediate host as these beetles readily colonize products such as flour or cereals.
Hymenolepis
Published in Dongyou Liu, Handbook of Foodborne Diseases, 2018
First described as Taenia nana by Von Siebold in 1852, Hymenolepis nana (commonly known as dwarf tapeworm, nanos = dwarf) is a tiny intestinal tapeworm of humans (particularly children) that has the ability to complete its life cycle in a single host and to transmit via the fecal-oral route from one infected person to another without an intermediate host. In contrast, Hymenolepis diminuta (commonly known as rat tapeworm) is a zoonotic intestinal tapeworm of rodents and humans, whose life cycle involves an intermediate host (usually arthropods). Morphologically, H. nana is characterized by its smaller size and its possession of rostellar hooks and linear reproductive organs, whereas H. diminuta is much larger, has no rostellar hooks, and its reproductive organs are arranged in a triangular formation.
The Helminths
Published in Donald L. Price, Procedure Manual for the Diagnosis of Intestinal Parasites, 2017
The adult tapeworms of Hymenolepis diminuta are common parasites of the intestines of rats and mice. The intermediate hosts are fleas, beetles, and cockroaches. Man becomes an accidental definitive host after ingesting the intermediate host infected with the larval stage, most probably when eating dried fruit infested by small infected beetles.
Impact of gut microbiome on skin health: gut-skin axis observed through the lenses of therapeutics and skin diseases
Published in Gut Microbes, 2022
Md. Rayhan Mahmud, Sharmin Akter, Sanjida Khanam Tamanna, Lincon Mazumder, Israt Zahan Esti, Sanchita Banerjee, Sumona Akter, Md. Rakibul Hasan, Mrityunjoy Acharjee, Md. Sajjad Hossain, Anna Maria Pirttilä
The three most essential roles that the gut microbiome plays from birth are protection, providing metabolic activities and immune system development and regulation.6,7 At the beginning of life, gut microbial communities have a role in defending the host against pathogenic organisms. Throughout the life, they provide metabolic services, such as digestion of breast milk and other food. Members of microbiome help in degradation of toxins and drugs and in the biosynthesis of vitamins.6 The gut is considered to be in a state of symbiosis, because it is populated by a diverse group of microorganisms, and the host tolerates these commensal bacteria and associated benign antigens.8–10 The ability of the immune system to build a tolerance to benign antigens is built through ontogeny and the reduction of microbiome-dependent inflammatory responses.10,11 For example, in mice, long-term colonization by benign Hymenolepis diminuta results in modification of the immune system without causing dysbiosis and give protection against immune-mediated inflammatory diseases (IMIDs).12
Promising treatment strategies to combat Staphylococcus aureus biofilm infections: an updated review
Published in Biofouling, 2020
P. S. Seethalakshmi, Riya Rajeev, George Seghal Kiran, Joseph Selvin
Niclosamide is an antihelminthic drug used to treat Hymenolepis diminuta tapeworm infections in humans (Pearson and Hewlett 1985). Torres et al. (2016) found that niclosamide inhibited planktonic growth of S. aureus by 50% at a concentration of 1.2 µM, and inhibited the growth of cells in a biofilm by 50% at 6 µM. Zhurina et al. (2017) reported that 50% inhibition of biofilm formation was observed when S. aureus MFP03 and S. aureus 209 P strains were grown at 0.77 µg ml−1 and 0.05 µg ml−1 niclosamide, respectively. In addition to this, the study also concluded that a weak additive anti-biofilm activity was observed when azithromycin at 0.5 μg ml−1 was used in combination with 0.025 μg ml−1 niclosamide against S. aureus 209 P. Gwisai et al. (2017) reported that niclosamide exhibited antibacterial activity at MIC concentration in the range 0.156-0.313 µg ml−1 against MRSA. Also, niclosamide coatings were effective in preventing the attachment of S. aureus, hence the application of niclosamide can be extended as antimicrobial coatings in medical devices.
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