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The Parasitic Protozoa and Helminth Worms
Published in Julius P. Kreier, Infection, Resistance, and Immunity, 2022
The trematodes, commonly known as flukes or flatworms, are generally hermaphroditic and have a flattened, leaflike appearance. They possess two suckers and an abbreviated digestive tract. All require a mollusc as an intermediate host. Depending on the fluke species, adults may reside in various organs of humans including the intestine, liver, lung, or blood vessels. Clinically, the blood flukes (schistosomes) are the most important and these are discussed further below.
Phytolacca dodecandra (African Soapberry) and Picrorhiza kurroa (Kutki)
Published in Azamal Husen, Herbs, Shrubs, and Trees of Potential Medicinal Benefits, 2022
K. Meenakshi, Mansi Shah, Indu Anna George
P. dodecandra is famous in Africa for its molluscicidal activity, which can be used to block the transmission of schistosomiasis (Esser et al., 2003; Lemma, 1970). Schistosoma (blood flukes) are waterborne parasites of humans, and schistosomiasis is an infection that occurs when human skin encounters contaminated freshwater which is home to certain types of snails that carry the blood flukes. Chronic infections may cause an increased risk of liver fibrosis or bladder cancer.
Introduction to Cancer
Published in David E. Thurston, Ilona Pysz, Chemistry and Pharmacology of Anticancer Drugs, 2021
Certain parasitic worms are known to be carcinogenic. These include Clonorchis sinensis (the organism causing Clonorchiasis) and Opisthorchis viverrini (causing Opisthorchiasis), which have both been associated with cholangiocarcinoma. In addition, Schistosoma species (the organisms causing Schistosomiasis) have been associated with bladder cancers. For example, Schistosoma haematobium is a highly prevalent blood fluke and human parasite with a proven link to malignant bladder cancer.
Recent trends in praziquantel nanoformulations for helminthiasis treatment
Published in Expert Opinion on Drug Delivery, 2022
Ana C. Mengarda, Bruno Iles, João Paulo F. Longo, Josué de Moraes
Helminth infections are caused by different species of platyhelminths and nematodes. Platyhelminths (also known as flatworms) include flukes (also known as trematodes), such as schistosomes, and tapeworms (also known as cestodes), such as the pork tapeworm that causes cysticercosis. One of the most impactful is schistosomiasis, which is caused by infection with intravascular flatworms (blood flukes) of the genus Schistosoma [2,3]. These helminth infections are often a cause of serious animal mortality and morbidity, resulting in considerably reduced economic output among domestic animals, mainly cattle, goats, sheep, pigs, horses, and camels, with several species involved. For example, it has been estimated that 165 million cattle are infected with schistosomiasis worldwide [4]. In humans, schistosomiasis is clearly linked to poverty and despite affecting more than 240 million individuals, it continues to be neglected [3,5]. Food-borne trematodes, which are mainly caused by liver flukes (Fasciola spp., Opisthorchis spp., and Clonorchis sinensis), intestinal flukes (Heterophyes spp., Echinostoma spp., Metagonimus spp., and Fasciolopsis buski), and lung flukes (Paragonimus spp.) are also important human helminthiasis, affecting over 50 million people worldwide [6].
Design, synthesis, and in vitro evaluation of aza-peptide aldehydes and ketones as novel and selective protease inhibitors
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2020
Thomas S. Corrigan, Leilani M. Lotti Diaz, Sarah E. Border, Steven C. Ratigan, Kayla Q. Kasper, Daniel Sojka, Pavla Fajtova, Conor R. Caffrey, Guy S. Salvesen, Craig A. McElroy, Christopher M. Hadad, Özlem Doğan Ekici
Legumains are also clan CD cysteine proteases, sharing a common fold with caspases that is unique to this clan. Legumains are acidic lysosomal enzymes that strictly require an asparagine residue at the P1 position in order to cleave peptide substrates30. Legumain is abundant in human solid tumours and promotes cell migration, tissue invasion and metastasis31. The overexpression of legumain in tumour tissues32 makes it an attractive target for cancer therapy. Legumain has been described in plants; mammals33,34; the human blood fluke, Schistosoma mansoni35; the protozoan parasite, Trichomonas vaginalis7; and the ticks, Ixodes ricinus36 and Haemaphysalis longicornis31. In the intestine of S. mansoni and I. ricinus, legumains contribute to digestion of the blood meal proteins37, including haemoglobin, and trans-activate other protease zymogens involved in protein digestion38. Therefore, in addition to cancer therapy, the selective inhibition of legumains also offers a therapeutic opportunity to effectively treat the diseases caused or transmitted by these parasites39 which affect over 200 million people worldwide, with a great majority being located in Africa40.
Imported African schistosomiasis and the potential risk of transmission in China
Published in Pathogens and Global Health, 2018
Jing Cui, Peng Jiang, Yan Yan Song, Xi Zhang, Zhong Quan Wang
African schistosomiasis is caused primarily by the blood flukes S. haematobium or S. mansoni. S. hematobium infection is endemic primarily in Africa and the Middle East, and causes urinary schistosomiasis. S. mansoni infection is distributed around the world, predominantly in Africa, the Near East, South America and the Caribbean, and produces intestinal schistosomiasis [1]. Both Schistosoma species are transmitted by intermediate host snails. Human infection is caused by skin contact with cercaria-contaminated freshwater during swimming, fishing or bathing. The principal clinical manifestations of S. haematobium infection are bladder irritation, hematuria, and urinal tract blockages, whereas the manifestations of S. mansoni infection are usually relatively mild, such as fever, abdominal pain, diarrhea, and weakness. Some patients may be mild or asymptomatic [5]. More than 90% of cases with African schistosomiasis occur in Africa, and China is a non-endemic area. However, an increasing number of Chinese citizens travel to Africa for work or leisure following the development of economic programs and tourism, the globalization of international trade, cultural exchange and China-aided projects in Africa. More than one million Chinese workers are working in Africa and approximately 900,000 Chinese people vacation in Africa each year [6]. There is an increasing trend for cases of African schistosomiasis in China. In this study, we report two cases of African schistosomiasis imported from Tanzania and Madagascar to China and discuss its potential transmission risk in China.