The Experimental Transmission of Human Intestinal Protozoan Parasites

Wastewater reuse contributes to closing the nutrient recycling loop as a sustainable way of managing water resources. Bangkok has over a thousand man-made drainage and irrigation canals for such purposes. Its use for agricultural and recreational purposes has a long tradition in rural and peri-urban areas. However, the continuation of these practices is increasingly questioned since potential health risks are an issue if such practices are not appropriately managed. The microbial and chemical quality of canal water has considerably deteriorated over the last decade, mainly because of discharged, untreated domestic and industrial wastewater. It is important to understand the health risks of wastewater reuse and identify risky behaviors from the most highly exposed actors promote the safe use of wastewater. This study assessed diarrhea infection risks caused by the use of and contact with wastewater in Klong Luang municipality, a peri-urban setting in Northern Bangkok, using quantitative microbial risk assessment. Wastewater samples were collected from canals, sewers at household level, and vegetables grown in the canals for consumption. Samples were also collected from irrigation water from the agricultural fields. Two protozoa, Giardia lamblia and Entamoeba histolytica, were quantified and analyzed by real-time PCR, exposure assessment was conducted, and finally, the risk of infection due to contact with wastewater in different scenarios was calculated. The results showed that canal water and vegetables were heavily contaminated with G. lamblia and E. histolytica. Infection risk was high in tested scenarios and largely exceeded the acceptable risk given by WHO guidelines.

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“…For E. histolytica, N 50 = 341, a = 0.1008 (Rendtorff 1954). The P inf in both cases above is probability of infection by a single exposure.…”

Section: Dose-response Assessmentmentioning

confidence: 99%

Quantification of Diarrhea Risk Related to Wastewater Contact in Thailand

2012

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“…5 Symptoms may last for several weeks even after clearance of the parasite, due to acquired lactose intolerance which may occur in 20e 40% of cases. 6 One study has shown that 16% of infected individuals became chronically infected.…”

Section: Introductionmentioning

confidence: 99%

“…6 One study has shown that 16% of infected individuals became chronically infected. 5 These patients experience variable symptoms of loose stools, weight loss, abdominal pain, malabsorbtion and malaise. Symptoms of chronic giardiasis are often indistinguishable from irritable bowel syndrome.…”

Section: Introductionmentioning

confidence: 99%

Persisting symptoms and duodenal inflammation related to Giardia duodenalis infection

Hanevik

Hausken

Morken

et al. 2007

Journal of Infection

129

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In patients with persisting symptoms after metronidazole treated Giardia infection we commonly found chronic Giardia infection and microscopic duodenal inflammation, especially in illness duration less than 7 months. Both these findings subsided over time. Increasingly, investigations could not determine a definite cause for the persistent symptoms. The very long-term post-giardiasis diarrhoea, bloating, nausea and abdominal pain documented here need further study.

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“…Der Entwicklungszyklus erfolgt innerhalb eines einzigen Wirtes; die Ausscheidung der Giardia-Zysten in z. T. sehr hohen Konzentrationen kann sich über mehrere Monate erstrecken. Die Infektionsdosis wird mit weniger als 10 Zysten angegeben und als sehr niedrig eingestuft; die Inkubationszeit beträgt median 7-10 Tage [8,9,10] [9,11,12,13]. Die Prävalenz der Giardiasis wird in den industrialisierten Ländern mit 2-5% angegeben; in den USA gilt Giardia lamblia als der häufigste nachgewiesene intestinale Parasit [2,8,14].…”

Section: Giardia Lambliaunclassified

Durch Trinkwasser �bertragene parasit�re Zoonosen

Exner

Gornik

2004

Bundesgesundheitsbl - Gesundheitsforsch - Gesundheitsschutz

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Nowadays, the parasitic zoonose organisms Giardia lamblia und Cryptosporidium spp. are among the most relevant pathogens of drinking water-associated disease outbreaks. These pathogens are transmitted via a fecal-oral route; in both cases the dose of infection is low. Apart from person-to-person or animal-to-person transmissions, the consumption of contaminated food and water are further modes of transmission. The disease is mainly characterized by gastrointestinal symptoms. In industrialized countries, the prevalence rate of giardiasis is 2-5 % and of cryptosporidiosis 1-3%. Throughout the world, a large number of giardiasis and cryptosporidiosis outbreaks associated with drinking water were published; in 2001 the first case in Germany was identified. Giardia and Cryptosporidium are detected in surface water and sporadically in unprotected groundwater. Use of these waters for drinking water abstraction makes high demands on the technology of the treatment process: because of the disinfectant resistance of the parasites, safe elimination methods are needed, which even at high contamination levels of source water guarantee safe drinking water. Further measures for prevention and control are implementation of the HACCP concept, which includes the whole chain of procedures of drinking water supply from catchment via treatment to tap and a quality management system.

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The Experimental Transmission of Human Intestinal Protozoan Parasites

Cited by 188 publications

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Quantification of Diarrhea Risk Related to Wastewater Contact in Thailand

Quantification of Diarrhea Risk Related to Wastewater Contact in Thailand

Persisting symptoms and duodenal inflammation related to Giardia duodenalis infection

Durch Trinkwasser �bertragene parasit�re Zoonosen

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