Assessing viability and infectivity of foodborne and waterborne stages (cysts/oocysts) of Giardia duodenalis, Cryptosporidium spp., and Toxoplasma gondii: a review of methods

Open Access

Review

Table 1

Methods to determine (oo)cyst infectivity and their application in exposure assessment.

Methods	Parasites	Applications

		Detection in naturally contaminated samples	Determination of the efficacy of control measures^a
Bioassays − Ability of (oo)cysts to induce infection of animals	Cp	River water [210] Wastewater [109] Mussels, clams, oysters, cockles [67,69,70,71,88,90,143]	Simple matrix^b: H₂O₂-based disinfectants [176] Chlorine dioxide [198] Ozone [141,187], ozone + monochloramine/ + chlorine [27,28] Salinity: 10, 20 and 30 ppt of salt at 10 °C or 20 °C (12 w) [68] UV [11,46,148,154,187,195,198] US [172] Pasteurization [99] Storage 15 °C (9 m) [115] Storage 4 °C and 10 °C (8 w) [142] Storage −10 °C to + 35 °C (24 w) [68]
			Food matrix: UV − Fresh apple cider [98] PUV − Raspberries [131] HHP, e-beam, microwaves − Oysters [42,43] Heat (steam cooking) − Mussels [91] Pasteurization − Milk [99] Storage 6 °C (4 w) – Apple [150]
	G	Wastewater [82,109,140]	Simple matrix:
		Raw and chlorinated drinking water [111]	Ozone [74]
			UV [37,139,140,154,196]
			Gamma irradiation [203]
	T	Water [12,110,219] Oysters, mussels [63]	Simple matrix:
			Chlorine [222]
			Ozone [59,222]
			UV [59,220,223]
			HHP [145]
			Gamma-irradiation [55]
			Radiofrequency [221]
			Storage −10 °C to 70 °C (up to 54 m) [53]
			Food matrix:
			HHP − Raspberries [146]
			Storage 4 °C (up to 8 w) − Raspberries and blueberries [126]
Cell culture infection −	Cp	Wastewater [85] Water [133,190]	Simple matrix:
Cell culture infection −			Chlorine [15,193], Chlorine dioxide [198], MOS [122]
Ability of (oo)cysts to invade and infect cells			Ozone [122,187]
			UV [83,122,123,186,187,195,198]
			Heat 38 °C to 70 °C [193]
			Storage 15 °C (9 m) [115]
			Food matrix:
			Organic acids and hydrogen peroxide − Fruit juices [127]
	Ch	NA	Simple matrix:
			UV [118]
	T	NA	Simple matrix:
			Chlorine [218]
			Iodophore-based disinfectants, formalin, acidified ethanol [218]
			Ozone [59]
			UV [59,223]

Relevant for water and food industries;

Simple matrix: water or buffer.

NA: No available data. Cp: C. parvum; Ch: C. hominis; G: Giardia duodenalis; T: Toxoplasma gondii.

H₂O₂: hydrogen peroxide; MOS: mixed-oxidant solution; UV: ultraviolet; PUV: pulsed-ultraviolet; HHP: high hydrostatic pressure; US: ultrasound; m: months; w: weeks.

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