The Parasite's Way of life
Eric S. Loker, Bruce V. Hofkin in Parasitology, 2015
Following parasite reproduction within a host, eggs or larvae must often be released to the external environment or must pass directly to the next host in the life cycle. The anatomical structure through which propagules move is called the portal of exit. For parasites of the gastrointestinal tract, the usual portal of exit is the anus. Vector-borne parasites rely on the feeding behavior of an arthropod both for host ingress and egress. Genital contact serves this same dual function for sexually transmitted parasites such as Trichomonas vaginalis. It is not always true, however, that the portal of exit is part of the same anatomical structure or even the same organ system as the one through which the parasite enters a host. Hookworms, for instance, infect their definitive host when larvae burrow through the skin. Following an extensive migration, they ultimately arrive in the intestine where they mature sexually. Fertile eggs exit the definitive host with the feces. In the schistosomes, cercariae enter the definitive host by direct penetration of the skin. Eggs, however, are released through the feces or the urine, depending on species (Figure 3.22).
The Parasite's Way of Life
Eric S. Loker, Bruce V. Hofkin in Parasitology, 2023
Following parasite reproduction within a host, eggs or larvae must often be released to the external environment or must pass directly to the next host in the life cycle. The anatomical structure through which propagules move is called the portal of exit. For parasites of the gastrointestinal tract, the usual portal of exit is the anus. Vector-borne parasites rely on the feeding behavior of an arthropod both for host ingress and egress. Genital contact serves this same dual function for sexually transmitted parasites such as Trichomonas vaginalis. It is not always true, however, that the portal of exit is part of the same anatomical structure or even the same organ system as the one through which the parasite enters a host. Hookworms, for instance, infect their definitive host when larvae burrow through the skin. Following an extensive migration, they ultimately arrive in the intestine where they mature sexually. Fertile eggs exit the definitive host with the feces. In the schistosomes, cercariae enter the definitive host by direct penetration of the skin. Eggs, however, are released through the feces or the urine, depending on species (Figure 3.25).
Diethylcarbamazine
M. Lindsay Grayson, Sara E. Cosgrove, Suzanne M. Crowe, M. Lindsay Grayson, William Hope, James S. McCarthy, John Mills, Johan W. Mouton, David L. Paterson in Kucers’ The Use of Antibiotics, 2017
As treatment for T. trichiura infection, combination therapy of DEC and albendazole does not confer additional benefit to treatment with albendazole alone (Ismail and Jayakody, 1999; Belizario et al., 2003). In the study cited above, it was also observed that treatment with DEC led to no significant decline in hookworm egg output (Meyrowitsch and Simonsen, 2001). Although other studies have demonstrated effective treatment of hookworm with the combination of DEC and albendazole in mass drug administration programs, this effect could be explained by the well-known efficacy of albendazole alone against hookworm (Oqueka et al., 2005). In Haitian children it was demonstrated that DEC alone was less effective than albendazole alone in reducing the prevalence of infection with Ascaris, Trichuris, and hookworm (Fox et al., 2005).
Dynamics of the bacterial gut microbiota during controlled human infection with Necator americanus larvae
Published in Gut Microbes, 2020
Q. R. Ducarmon, M. A. Hoogerwerf, J. J. Janse, A. R. Geelen, J. P. R. Koopman, R. D. Zwittink, J. J. Goeman, E. J. Kuijper, M. Roestenberg
Helminths such as hookworms can have beneficial effects on auto-immune diseases1,2 such as celiac disease,3,4 but also cause eosinophilic gastroenteritis, anemia and protein loss and are therefore responsible for a high burden of disease in low- and middle-income countries.5 As a part of the human gut microbiome in developing countries with a high rate of hookworm infections, hookworms can exert evolutionary pressure on the bacterial gut ecosystem through intestinal motility, mucin glycosylation, mucus secretion, epithelial damage and worm products.6 For example, several helminths and their products have been shown to increase permeability of monolayers in cell culture.7,8 In addition, worm products can have direct antibacterial activity, thereby having the potential to directly alter the bacterial gut microbiota.9,10 However, the complex interplay between hookworms such as Necator americanus and the bacterial microbiota is largely unknown.
High burden of soil-transmitted helminth infections, schistosomiasis, undernutrition, and poor sanitation in two Typhoon Haiyan-stricken provinces in Eastern Philippines
Published in Pathogens and Global Health, 2021
Vicente Belizario, John Paul Caesar Robles Delos Trinos, Olivia Sison, Esther Miranda, Victorio Molina, Agnes Cuayzon, Maria Epifania Isiderio, Rodel Delgado
Ascariasis and trichuriasis prevalence was not significantly different in PSAC (p-value = 0.19). Among SAC, however, trichuriasis prevalence was significantly higher than ascariasis prevalence (p-value = <0.001). This may be due to the lower efficacy against trichuriasis of albendazole, which is the drug used in school-based targeted PC[1]. The low hookworm infection prevalence may reflect the limitation of Kato–Katz technique, wherein hookworm ova disintegrate hours after smear preparation [26], as well as the difference in transmission. Hookworm infection is transmitted through larval skin penetration and may be more common in adults in certain occupations such as farming, compared with ascariasis and trichuriasis, which are transmitted through ingestion of ova and are more common in children [13,32].
Comparison of ELISA and PCR of the 18S rRNA gene for detection of human strongyloidiasis using serum sample
Published in Infectious Diseases, 2019
Mostafa Javanian, Tahmineh Gorgani-Firouzjaee, Narges Kalantrai
A total of 272 patients participated in the present study including 153 cases with infectious diseases and 119 subjects with immunosuppressive conditions. The demographic information of the patients is listed in Table 1. The mean age of the immunosuppressed patients was 56.2 ± 14.5, ranging from 13 to 86 years. The mean age of patients with infection was 56.7 ± 15.8, with a range of 13-87 years. Out of 272 subjects, 220 participants provided stool specimens which were examined with three parasitological techniques to evaluate the presence of S. stercoralis larvae and other possible helminth infections. Fourteen out of 220 (6.3%) specimens were positive for S. stercoralis larvae by stool examination (Table 1). One sample was positive for hookworm eggs in a patient with infectious diseases. This patients serum was negative for Strongyloides infection using parasitological, ELISA and PCR techniques.
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- Ancylostoma Caninum
- Ancylostoma Duodenale
- Gastrointestinal Tract
- Helminthiasis
- Necator Americanus
- Hematophagy
- Hookworm Infection
- Ancylostoma Braziliense
- Ancylostoma Tubaeforme
- Ancylostoma Pluridentatum