The Parasitic Protozoa and Helminth Worms
Julius P. Kreier in Infection, Resistance, and Immunity, 2022
Giardia lamblia, also known as Giardia duodenalis or Giardia intestinal is, is usually considered to be a harmless commensal of the small intestine, but it can cause malabsorption and severe diarrhea. Evidence for acquired immunity is circumstantial, but there is usually spontaneous clearance and resistance to reinfection. Epidemiological studies indicate that those living in endemic areas are less affected than visitors, the young are more affected than adults and immunodepressed individuals tend to experience long chronic infections. Secretory IgA is the most characteristic Giardia-specific antibody in patients with acute giardiasis, but there is little direct evidence of any IgA antiparasitic effects although specific antibodies occur in human milk and saliva and breast-fed infants in endemic areas seem to acquire some protection. Overall immunity to giardiasis seems to be similar to immunity to a number of bacterial infections in which secretory IgA in breast milk protects the newborn infant until it can produce its own IgA. IgA probably prevents attachment to the villi. Giardia lamblia can undergo antigenic variation, but it is not known how this might affect the acquisition of immunity to this parasite. There have been reports of giardiasis in AIDS patients, but this infection is not a major concomitant of HIV infections.
Waterborne zoonoses *
Jamie Bartram, Rachel Baum, Peter A. Coclanis, David M. Gute, David Kay, Stéphanie McFadyen, Katherine Pond, William Robertson, Michael J. Rouse in Routledge Handbook of Water and Health, 2015
Giardia duodenalis(also known as Giardia lamblia and Giardia intestinalis) is the cause of both acute and chronic diarrheal illness and dehydration worldwide. In the developed world the prevalence is thought to be between 0.4 and 7.5 percent, whereas in the developing world the prevalence is estimated to be between 8 and 30 percent (Feng and Xiao 2011). Baldursson and Karanis (2011) reported that Giardia lamblia (duodenalis) were associated with 35.2 percent of 199 recorded waterborne disease outbreaks worldwide between 2004 and 2010. While they are occasionally associated with foodborne disease they are also a leading cause of waterborne outbreaks and sporadic disease. Craun et al. (2010) reported that G. intestinaliswas the sole pathogen in 123 (86.0 percent) of the 143 drinking water outbreaks associated with protozoa in the USA from 1971 to 2006. These outbreaks caused 28,127 cases of giardiasis with an average of 228 cases per outbreak. A large outbreak also occurred in Bergen, Norway, in 2004 resulting in 1,300 laboratory-confirmed cases of giardiasis. The cause of the outbreak is suspected to have been leakage of sewage pipes into a drinking water source. Interestingly, follow-up studies conducted three years after the outbreak found that a significantly higher proportion of those that had acute Giardia infections than controls suffered from irritable bowel syndrome (46.1 percent versus 14 percent) and chronic fatigue syndrome (46.1 percent versus 12 percent) (Wensaas et al. 2012).
Blastocystis
Dongyou Liu in Handbook of Foodborne Diseases, 2018
The pathogenicity of Blastocystis is still controversial, so it is doubtful to what extent prevention from Blastocystis infection should be prioritized. To date, no prophylaxis or vaccine studies for Blastocystis have been carried out. Despite some gaps in the life cycle, the most accepted transmission method of Blastocystis is the fecal-oral route. Therefore, prevention strategies for Blastocystis infection may be similar to other zoonotic intestinal protozoa, such as Cryptosporidium sp. and Giardia intestinalis. Preventing food and water sources from fecal contamination, animal handling, and improvement of personal hygiene seem to be effective for the prevention of Blastocystis infection.28,112,113
Novel therapeutic opportunities for Toxoplasma gondii, Trichomonas vaginalis, and Giardia intestinalis infections
Published in Expert Opinion on Therapeutic Patents, 2023
Francesca Arrighi, Arianna Granese, Paola Chimenti, Paolo Guglielmi
Giardia intestinalis (syn., G. lamblia, G. duodenalis) is, similar to T. vaginalis, a flagellate protozoan involved in the insurgence of intestinal infection called giardiasis [32]. Its life cycle includes trophozoite and cystic forms. After ingestion of giardia cysts, typically via contaminated food or water or via the fecal-oral route, they direct to the stomach, where host proteases and acidic pH weaken cyst walls beginning the excystation, that is complete in the upper small intestine [33]. The released vegetative trophozoites divide by binary fission and attach to the small intestinal lumen epithelium via a ventral adhesive disk. The completion of life cycle is reached when trophozoites, after detachment, move along the GI tract where they are exposed to bile, and initiate encystation to create new cysts that are excreted into the environment [34]. Giardia intestinalis infection can occur without symptoms or exhibiting acute watery diarrhea, nausea, epigastric pain, and weight loss [32].
Prevalence and associated risk factors of intestinal parasitic infections in Kurdistan province, northwest Iran
Published in Cogent Medicine, 2018
Fares Bahrami, Ali Haghighi, Ghasem Zamini, Mohammad Bagher Khadem-Erfan, Eznolla Azargashb
In developing countries, intestinal parasitic infections (IPIs) are the most common infections (Sayyari, Imanzadeh, Bagheri Yazdi, Karami, & Yaghoobi, 2005). If IPIs are not recognized and treated appropriately, they can result in significant morbidity and mortality (Gilles & Hoffman, 2002). IPIs can be caused by protozoan organisms or helminths. The most common intestinal pathogenic parasites include: Giardia intestinalis, Entamoeba histolytica/E. dispar, Cryptosporidium spp., microsporidia, Cyclospora cayetanenensis, Ascaris lumbricoides, Ancylostoma duodenale, Blastocystis sp. Necator americanus, Hymenolepis nana, Taenia saginata, and Trichuris trichiura (Haque, 2007; Horton, 2003).
The incidence of laboratory-confirmed cases of enteric pathogens in Denmark 2018: a national observational study
Published in Infectious Diseases, 2023
Anna Tølbøll Svendsen, Hans Linde Nielsen, Peter Bytzer, John Eugenio Coia, Jørgen Engberg, Hanne Marie Holt, Lars Lemming, Steen Lomborg, Ea Sofie Marmolin, Bente Scharvik Olesen, Leif Percival Andersen, Steen Ethelberg, Anne Line Engsbro
We found that the most commonly detected pathogen in travel-related cases was ETEC, followed by Shigella species/EIEC where 92% and 85% of cases, respectively, were travel-related. For Giardia intestinalis and Cryptosporidium spp., approximately two-thirds were travel-related. Travel history was largely unknown for the viral pathogens. Our findings agree with the most common pathogens reported in travellers’ diarrhoea by previous reports [22,23] and the US CDC [29]. Due to the low report on travel history for many enteropathogens, we are unable to provide estimates on relative proportions on bacterial, viral and parasitic pathogens in travellers’ diarrhoea in Denmark.
Related Knowledge Centers
- Flagellate
- Gastrointestinal Tract
- Giardia
- Intestinal Epithelium
- Parasitism
- Small Intestine
- Giardiasis
- Reproduction
- Lumen
- Host