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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
Parasitic protozoa also are capable of impressive feats of reproduction. Asexual reproduction, usually via binary fission, is a common feature of the parasitic protozoan life cycle. Entamoeba histolytica, for instance, is the primary agent responsible for amebic dysentery in humans. This strictly human parasite has a direct life cycle. Transmission is via the fecal–oral route. The infective stage (the cyst) contains four trophozoites formed by two rounds of cell division. Following ingestion, the cyst passes through the stomach to the lower portion of the small intestine where excystation and trophozoite release occurs. These trophozoites migrate to the large intestine where they feed on cellular debris and bacteria and undergo multiple rounds of binary fission. Under certain conditions, many of which remain to be characterized, trophozoites encyst and are released with the feces.
Infectious Disease
Published in John S. Axford, Chris A. O'Callaghan, Medicine for Finals and Beyond, 2023
Susanna J. Dunachie, Hanif Esmail, Ruth Corrigan, Maria Dudareva
Protozoa are unicellular organisms, some of which are important pathogens of humans. They include Plasmodium, the causative organism of malaria, which is responsible for around one million deaths each year worldwide. Some protozoa have a complex life cycle that includes a vector, whereas others spread from person to person by the faecal–oral route. Many protozoa such as Leishmania and Trypanosoma are adapted to an intracellular environment (Table 3.11).
Neuroinfectious Diseases
Published in Philip B. Gorelick, Fernando D. Testai, Graeme J. Hankey, Joanna M. Wardlaw, Hankey's Clinical Neurology, 2020
Jeremy D. Young, Jesica A. Herrick, Scott Borgetti
T. gondii is considered a zoonosis, but it can spread through multiple mechanisms. In patients with AIDS-related toxoplasmic encephalitis, there is no epidemiologic association with cat ownership, and it is an unreliable historical factor.1 Transmission is often remote and unrelated to contact with a felid. The protozoan is present in the environment worldwide.
The management of Babesia, amoeba and other zoonotic diseases provoked by protozoa
Published in Expert Opinion on Therapeutic Patents, 2023
Clemente Capasso, Claudiu T. Supuran
Protozoa are simple eukaryotic organisms (monocellular organisms) that are diverse of plants, animals, or fungi and can live free or as parasites of other organisms [1,2]. Fecal-oral transmissions, food or water contaminated with the feces of infected animals, and person-to-person contact are the standard modes of transmission for intestinal pathogenic protozoa [1,2]. At the same time, the bite of a mosquito or sandfly (arthropod vectors) is responsible for the spread of protozoa residing in human or animal blood (or other tissues) [3]. Many asymptomatic animals can spread protozoal infections such as babesiosis, amebiasis toxoplasmosis, Chagas’ disease, and leishmaniasis, making them particularly pernicious [4–6]. Immunocompromised persons, especially the growing number of obese and/or diabetic patients, are at a considerably risk of developing such zoonosis [5]. Thus, these frequently ignored veterinary and human diseases for which few therapeutic options are available, should be considered in more detail both for their management with the few available drugs but also in the context of designing novel anti-protozoan agents with an enhanced efficacy and less side effects [7,8].
Systemic Miltefosine as an Adjunct Treatment of Progressive Acanthamoeba Keratitis
Published in Ocular Immunology and Inflammation, 2021
Andrea Naranjo, Jaime D. Martinez, Darlene Miller, Rahul Tonk, Guillermo Amescua
Acanthamoeba keratitis (AK) is one of the most challenging infections ophthalmologists encounter in practice due to its wide range of clinical manifestations, symptoms, delayed diagnosis, and frequent lack of response to standard medical treatment.1 These challenges drive the clinical and research interest in developing novel, effective therapies for the condition. Acanthamoeba spp. are protozoa that are ubiquitous in air, soil, dust, and water.2 Its virulence factors include the secretion of multiple proteases, which help it degrade the corneal stroma and reach deep into the cornea.3 The parasite is thought to feed on keratocytes and has the ability to form cysts when facing adverse environmental challenges. The cysts constitute the dormant form of the organism which are able to survive even under nutrient deficiency and exposure to noxious injury.4 Current medical treatment for Acanthamoeba includes biguanides (polyhexamethylene biguanide (PHMB) and chlorhexidine);4 diaminides such as propamidine isethionate, dibromopropamidine, and hexamidine;5 and others such as neomycin and/or oral voriconazole.6 Steroid use still remains controversial4,7: past studies have shown that steroid treatment prior to anti-acanthamoeba therapy is detrimental,8 but more recent work has suggested that steroids, when introduced after 2 weeks of anti-amoebic treatment, may aide with discomfort without impairing outcomes.7
Inhibitory effect of Tunceli garlic (Allium tuncelianum) on blastocystis subtype 3 grown in vitro
Published in Expert Opinion on Orphan Drugs, 2020
Mehmet Aykur, Emrah Karakavuk, Muhammet Karakavuk, Mesut Akıl, Hüseyin Can, Mert Döşkaya, Yüksel Gürüz, Hande Dağcı
Blastocystis is one of the most common parasite detected in the intestinal tract of humans and animals worldwide [1]. The reasons for the widespread distribution of this parasite depend on the social behaviors and hygiene status related to geographic region, as well as exposure to animals and consumption of contaminated food or water [2,3]. Blastocystis can be found in more than onemillion people worldwide [4]. The prevalence of this parasite varies from 3 to 70% in different countries [3]. Moreover, the prevalence of Blastocystis was 100% in the rural areas of Senegal [5]. In Turkey, the frequency of Blastocystis among children and adults ranged from 31.7 to 32.8% [6]. Moreover, evaluation of the last decade showed that the most common parasite detected in stool samples was Blastocystis (39.8%) [7]. Similarly, Blastocystis is one of the most commonly detected protozoan parasite in stool samples examined in parasitology laboratories around the world [8].