Cysts Giardia

Isolation and Identification of Giardia Cysts, Cryptosporidium Oocysts and Eree Living Pathogenic Amoebae in Water etc., 1989... 

Identification may be by gross examination for adult helminths or, more commonly, by microscopic examination for protozoa, helminth eggs, and larvae. The diagnostic forms of some parasites, such as the eggs of Ascaris spp., are present on a regular basis. Other forms, such as malaria parasites, Taenia eggs, or Giardia cysts, vary from day to day. 

Giardia lamblia 7 days Diarrhea which can last 1-2 weeks Dose >1 cysts Sewage, manure, wild and domestic animals, infected food handlers and water... 

Giardia cysts persist for a shorter period in irrigation water compared to Cryptosporidium oocysts (Karim et al, 2004 Skraber et al., 2007). Temperatures as low as —4 °C inactivate Giardia cysts in water while Cryptosporidium oocysts remained viable for >12 weeks at 4 °C (Karim et al.,... 

At 25 °C, Giardia cysts were inactivated in water within 2 weeks but Cryptosporidium oocysts survived for >10 weeks. Factors affecting the survival of pathogens in water have been reviewed by Bichai et al. (2008). 

While Giardia is sensitive to freezing of soil, Cryptosporidium is more resistant. Mahdy et al. (2008) reported Giardia cysts in soil were inactivated after 7 days at -4 °C, but Cryptosporidium could survive for >12 weeks. However, persistence of both protozoa was reduced to 8 weeks at 4 °C and 4 weeks at 25 °C (Mahdy et al., 2008). Cryptosporidium have been shown to be particularly sensitive to drying. Various studies have shown less than 5% viability following 4 h of air drying at room temperature (Anderson, 1986 Nasser et al., 2007 Robertson et al, 1992). 

Albendazole has a broad spectrum of activity against intestinal nematodes and cestodes, as well as the fiver flukes Opisthorchis sinensis, Opisthorchis viverrini, and Clonorchis sinensis It also has been used successfully against Giardia lambfia. Albendazole is an effective treatment of hydatid cyst disease (echinococcosis), especially... 

The detection of new kinds of microorganisms, such as the cysts and oocysts of parasites (Giardia, Cryptosporidium), the identification of more and more chemical pollutants in waters and increasing quality levels required for drinking and waste waters has induced new interest in ozonation and ozone-based advanced oxidation processes. However, care has to be taken in the application of ozonation, since recent research has indicated that presumably hazardous by-products can be formed, e. g. bromate in the ozonation of waters containing bromide. 

Erdogrul, O. and ener, H. (2005) The contamination of various fruit and vegetables with Enterobius ver-micularis, Ascaris eggs, Entamoeba histolytica cysts and Giardia cysts. Food Control (5th International Meeting of the Noordwijk Food Safety and HACCP Forum) 16(6), 557-560. 

Another and more convincing explanation for this discrepancy of previous and recent studies related to the inactivation of Cryptosporidium refers to the methods of viability testing. So, it seems that in vitro viability assays (chemical excystation and vital stains) that have been used previously may have significantly underestimated the inactivation efficacy of UV-C irradiation of the parasites compared with in vivo infectivity assays applied in recent studies using neonatal mouse models (Craik et al, 2001). This was also demonstrated by UV inactivation of Giardia muris cysts using MP Hg lamps (Craik et al., 2000). 

In conclusion, the resent research by Clancy et al. (2000, 1998), Bukhari et al. (1999) and Craik et al. (2001) has convincingly demonstrated that UV-C is highly effective at inactivating Cryptosporidium parvum oocysts (and Giardia muris cysts)... 

Craik SA, Finch GR, Bolton JR, Belosevic M (2000) Inactivation of Giardia Muris Cysts Using Medium-Pressure Ultraviolet Radiation in Filtered Drinking Water, Wat. Res. 34, No. 18 4325-4332. 

Giardia lamblia. Giardia lamblia is a flagellate parasitic protozoan. This parasite is largely confined to the lining of the intestine. It can colonize the lining and feed and grow there. It is shed in feces in the form of cysts. The cyst, however, cannot multiply outside the host. 

Giardia cysts can be fonnd in water, raw vegetables, and feces of contaminated individnals. Where adeqnate sanitation cannot be maintained, the cysts can also be fonnd in institntions and day-care centers. The beaver has gained attention as a potential sonrce of Giardia contamination of lakes, reservoirs, and streams ... 

Measures to prevent transmission include proper disposal of feces, wastewater treatment, and a filtration step before chlorination in water treatment plants that draw from surface water sources. Cooking kills the cysts in contaminated foods and boiling will make water safe for use. For backpackers who walk through the wilderness, iodine has been shown to be a better disinfectant for giardia cyst than chlorine. It should be emphasized that of all the methods of preventing contamination from the cyst, a properly designed and operated water filtration plant is the best line of defense in drinking water supplies. 

Rendtorff, R. C. (1954). The experimental transmission of human intestinal protozoan parasites, II. Giardia lamblia cysts given in capsules. Am. J. Hyg. 59, 209-220. 

Hendricks, D. W. (1988). Filtration of Giardia Cysts and Other Particles under Treatment Plant Conditions (Research Report/AWWA Research Eoundation). Am. Water Works Assoc., Denver. 

The majority of the minimum design criteria in the Ten State Standards for diatomaceous earth (DE) systems meet the SWTR (2). However, two design criteria in addition to the Ten State Standards are necessary to meet current regulations (a) The minimum amount of filter precoat should he 1 kg/m (0.2 Ih/ft ) to enhance Giardia cyst removal and (b) the minimum thickness of the precoat should be increased from 0.3 to 0.5 cm (1/8 to 1/5 in.) (found to be more important than the size graduation of the diatomaceous earth), also to enhance Giardia cyst removal. 

The performance of each filter type depends on the quality of the influent and proper design and operation. The range of influent characteristics for which various filters are effective has been provided by the US EPA (3) in Tables 5 and 6. According to the two tables, DE filtration is an established process mostly for small water systems with good influent quality (less than 5 NTU turbidity, less than 5 color units, and less than 50/100-mL conform count) and low influent capacity (below 100 MGD). The removal capacities for Giardia cysts and viruses of the above seven filter systems are presented in Table 7. It is important to note that DE filtration is better than conventional filtration and direct filtration in terms of removal efficiency of Giardia cyst and viruses. 

Filtration Options Achievable Giardia cyst levels Achievable virus levels... 

The DE process is entirely a physical/mechaihcal operahon and can attain high log removals of Giardia cysts and Cryptosporidium oocysts without operator expertise in water chemistry relahng to coagulation (3,4,10,11,19-26). 

G. S. Logsdon, Removal of Giardia cysts and cyst models by filtration. Journal AWWA 73(2), 111 (1981). 

The disinfection efficiency is dependent on the UV dosage as well as the physical and chemical conditions of the water and air to be disinfected. It is found that an UV irradiation dose of 8-14 mJ/cm is required to meet the 3-log inactivation of Cryptosporidium spp. oocysts (i.e., 99.9% killing) and 12-20 mJ/cm is necessary to achieve at least 3-log inactivation of Giardia spp. cysts in drinking water disinfection (13). The UV can also be used in seawater disinfection. A filter system combined with a series of 0.45-pm filters can reduce by as much as 60% of the bacteria in raw seawater. An UV dose 63.6 mJ/cm is enough to achieve 4-log Vibrio and Pseudomonas bacteria reduction (14). 

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