A water contamination incident in Oslo, Norway during October 2007; a basis for discussion of boil-water notices and the potential for post-treatment contamination of drinking water supplies

Parasitology Laboratory, Department of Food Safety and Infection Biology, Norwegian School of Veterinary Science, Postbox 8146 Dep, 0033, Oslo, Norway.
Journal of Water and Health (Impact Factor: 1.46). 02/2009; 7(1):55-66. DOI: 10.2166/wh.2009.014
Source: PubMed


Over a 5 day period in October 2007 a boil-water notice was served on the majority of Oslo, capital city of Norway, as a result of a combination of bacteriological findings (coliforms, intestinal enterococci, and E. coli), and very low numbers of Cryptosporidium oocysts and Giardia cysts in 10 L water samples taken from the water distribution network. The water source had been regularly monitored for these parasites and generally found to be negative. Over 460,000 residents were affected by the boil-water notice, as were many thousands of businesses. Despite an extensive outbreak of waterborne giardiasis in Bergen, Norway during 2004/2005, occurrence of parasites in Norwegian drinking water supplies has apparently continued to be considered to be of minimal relevance by Norwegian health authorities. Here we describe the background and occurrence of the episode in Oslo, including the species of Cryptosporidium detected, and use this event, in conjunction with incidents from other countries, as a basis to discuss the following issues: (1) under which circumstances should the occurrence of Cryptosporidium oocysts and Giardia cysts in water supplies trigger the issue of a boil-water notice, and (2) the possibilities and probabilities of post-treatment contamination events in the water distribution network.

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    • "The management of the disorder is unsatisfactory [7]. Giardiasis is a major intestinal protozoan caused by the flagellate protozoan Giardia intestinalis (previously known as Giardia lamblia), and is the most commonly identified intestinal parasite in the United States and the most common protozoal intestinal parasite isolated worldwide [8] [9] [10]. Giardiasis is a water-borne disease transmitted through ingestion of infectious G. intestinalis cysts, [11] diarrhoea is the most common symptom of acute Giardia infection, occurring in 90% of symptomatic subjects [12] while chronic infection may present with dyspeptic symptoms that may be confused with other gastrointestinal and/or biliary disorders [13] [14]. "
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    Arab Journal of Gastroenterology 09/2013; 14(3):126-9. DOI:10.1016/j.ajg.2013.08.004
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    • "G. intestinalis; Giardia lamblia) is a flagellate enteric parasite that infects the intestinal tract of humans and a wide variety of other mammals through ingestion of infective cysts (van der Giessen et al., 2006). It is a major cause of non-viral/bacterial diarrhea affecting both developed and developing countries and more frequently encountered in areas with substandard environment, poor hygienic practices and inadequate water treatment system (Daly et al., 2010; Robertson et al., 2009). G. duodenalis infections are most often asymptomatic. "
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    ABSTRACT: Giardia duodenalis is considered the most common intestinal parasite in humans worldwide. In Malaysia, many studies have been conducted on the epidemiology of giardiasis. However, there is a scarcity of information on the genetic diversity and the dynamics of transmission of G. duodenalis. The present study was conducted to identify G. duodenalis assemblages and sub-assemblages based on multilocus analysis of the glutamate dehydrogenase (gdh), beta-giardin (bg) and triose phosphate isomerase (tpi) genes. Faecal specimens were collected from 484 Orang Asli children with a mean age of 7 years and examined using light microscopy. Specimens positive for Giardia were subjected to PCR analysis of the three genes and subsequent sequencing in both directions. Sequences were edited and analysed by phylogenetic analysis. Giardia duodenalis was detected in 17% (84 of 484) of the examined specimens. Among them, 71 were successfully sequenced using at least one locus. Genotyping results showed that 30 (42%) of the isolates belonged to assemblage A, 32 (45%) belonged to assemblage B, while discordant genotype results were observed in 9 specimens. Mixed infections were detected in 43 specimens using a tpi-based assemblage specific protocol. At the sub-assemblages level, isolates belonged to assemblage A were AII. High nucleotide variation found in isolates of assemblage B made subtyping difficult to achieve. The finding of assemblage B and the anthroponotic genotype AII implicates human-to-human transmission as the most possible mode of transmission among Malaysian aborigines. The high polymorphism found in isolates of assemblage B warrants a more defining tool to discriminate assemblage B at the sub-assemblage level.
    Infection, genetics and evolution: journal of molecular epidemiology and evolutionary genetics in infectious diseases 04/2013; 17. DOI:10.1016/j.meegid.2013.04.013 · 3.02 Impact Factor
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    • "Giardiasis is generally identified through microscope by the detection of trophozoites or cysts in water filtrate after staining methods or direct immune fluorescence (Janoff et al., 1992). Fecal-oral transfer of Giardia cysts is thus the major route for Giardiasis transmission (Robertson et al., 2009). "
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    ABSTRACT: Giardia lamblia is a cosmopolitan parasite that occurs worldwide and generally effects gastrointestinal tract. Water played a media for transmission of Giardia to different hosts. A total of 300 water samples were examined from different water sources, i.e. tap, open well, bore well and drain waters and DNA was extracted by trizol method through prescribed protocol. DNA was amplified through PCR. The overall prevalence of G. lamblia was 27.66% (83/300). Among these 2.5% (1/40) in bore well water, 29% (29/100) open well, 18.83% (11/60) tap water and 42% (42/100) drain water. It is concluded from the study that Giardia is frequently found in all water sources and is the main cause of ill health.
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