Aging of Cryptosporidium parvum oocysts in river water and their susceptibility to disinfection by chlorine and monochloramine

1998 ◽  
Vol 44 (12) ◽  
pp. 1154-1160 ◽  
Author(s):  
Christian Chauret ◽  
Kerry Nolan ◽  
Ping Chen ◽  
Susan Springthorpe ◽  
Syed Sattar
Keyword(s):  
Cryptosporidium Parvum ◽  
Environmental Fate ◽  
Water Environment ◽  
Water Disinfection ◽  
Ottawa River ◽  
In Situ Conditions ◽  
Cryptosporidium Parvum Oocysts ◽  
St Lawrence River

Cryptosporidium parvum oocysts were aged in waters from both the St. Lawrence River and the Ottawa River. In situ survival experiments were carried out by incubating the oocysts in either dialysis cassettes or microtubes floated into an overflow tank. A significant portion of the oocysts survived in the test waters for several weeks. Oocyst survival in the St. Lawrence River was better in membrane-filtered (0.2-µm-pore diameter) water than in unfiltered water, suggesting that biological antagonism may play a role in the environmental fate of the parasite. Oocysts aged in river waters under in situ conditions and control oocysts kept refrigerated in synthetic water (100 ppm as CaCO3; pH 7.0) were subjected to the same disinfection protocol. Aged oocysts were at least as resistant as, if not more resistant than, the control oocysts to disinfection. This indicates that the oocysts surviving in the water environment may be just as difficult to inactivate by potable water disinfection as freshly shed oocysts. Therefore, water treatment should not be based on the assumption that environmental oocysts may be more easily inactivated than freshly shed oocysts. First-order kinetics die-off rates varied from one river to another (from 0.013 to 0.039 log10·day-1) and from one experiment to another with water from the same river collected at different times. Calculation of the die-off rates based on either in vitro excystation or in vitro excystation in combination with total counts (overall die-off rates) showed that the assessment of oocyst viability by microscopic methods must account for the total oocyst loss observed during long-term inactivation assays of river waters.Key words: Cryptosporidium, survival, disinfection, biological antagonism.

scholarly journals Efecto de Caryodendron orinocense sobre la degradación de la materia seca

2017 ◽  
Vol 28 (3) ◽  
pp. 667
Author(s):  
Pablo Losada Aguilar ◽  
Aurora Cuesta Peralta ◽  
Juan De Jesús Vargas Martínez
Keyword(s):  
Crude Protein ◽  
Dry Matter ◽  
Animal Nutrition ◽  
Carbohydrate Concentration ◽  
Randomized Design ◽  
In Situ Conditions ◽  
Dry Matter Degradation ◽  
Animal Sciences

The objective of the present study was to evaluate the in vitro and in situ dry matter degradation by including cacay cake (Caryodendron orinocense) on a diet based on Brachiaria dictyoneura. The experiment was developed in an animal nutrition laboratory on the Animal Sciences Faculty at the Universidad de Ciencias Aplicadas y Ambientales, Bogotá, Colombia, in July 2015. Four treatments were evaluated: B. dictyoneura, cacay cake and two mixtures of B. dictyoneura: cacay cake (80:20 and 60:40). The chemical composition and the in vitro and in situ degradability of the dry matter and the crude protein, at 48 hours were determined. The variables were analyzed through a complete randomized design with four treatments. The inclusion of cacay cake decreased the cell wall-associated with carbohydrate concentration and increased the higher digestibility nutrients; the crude protein and dry matter, in situ and in vitro degradability increased 22, 6 and 38%, respectively. In conclusion, the inclusion of cacay cake on a diet of B. dictyoneura improves dry matter degradation in vitro and in situ conditions.

Intron-containing β-tubulin transcripts in Cryptosporidium parvum cultured in vitro

Microbiology ◽  
2004 ◽  
Vol 150 (5) ◽  
pp. 1191-1195 ◽  
Author(s):  
Xiaomin Cai ◽  
Cheryl A. Lancto ◽  
Mitchell S. Abrahamsen ◽  
Guan Zhu
Keyword(s):  
Life Cycle ◽  
Cryptosporidium Parvum ◽  
Late Life ◽  
Host Cells ◽  
Intron Splicing ◽  
Transcript Processing ◽  
Life Cycle Stages ◽  
Tubulin Mrna

The genome of Cryptosporidium parvum contains a relatively small number of introns, which includes the β-tubulin gene with only a single intron. Recently, it was observed that the intron was not removed from some of the β-tubulin transcripts in the late life cycle stages cultured in vitro. Although normally spliced β-tubulin mRNA was detected in all parasite intracellular stages by RT-PCR (e.g. HCT-8 or Caco-2 cells infected with C. parvum for 12–72 h), at 48–72 h post-infection unprocessed β-tubulin transcripts containing intact introns started to appear in parasite mRNA within infected host cells. The intron-containing transcripts could be detected by fluorescence in situ hybridization (FISH) using an intron-specific probe. The intron-containing β-tubulin transcripts appeared unique to the in vitro-cultured C. parvum, since they were not detected in parasite-infected calves at 72 h. As yet, it is unclear whether the late life cycle stages of C. parvum are partially deficient in intron-splicing or the intron-splicing processes have merely slowed, both of which would allow the detection of intron-containing transcripts. Another possible explanation is that the decay in transcript processing might simply be due to the onset of parasite death. Nonetheless, the appearance of intron-containing transcripts coincides with the arrest of C. parvum development in vitro. This unusual observation prompts speculation that the abnormal intron-splicing of β-tubulin transcripts may be one of the factors preventing complete development of this parasite in vitro. Furthermore, the presence of both processed and unprocessed introns in β-tubulin transcripts in vitro may provide a venue for studying overall mechanisms for intron-splicing in this parasite.

The effect of blueberry extracts on Giardia duodenalis viability and spontaneous excystation of Cryptosporidium parvum oocysts, in vitro

Methods ◽  
2007 ◽  
Vol 42 (4) ◽  
pp. 339-348 ◽  
Author(s):  
J.-P. Anthony ◽  
L. Fyfe ◽  
D. Stewart ◽  
G.J. McDougall ◽  
H.V. Smith
Keyword(s):  
Cryptosporidium Parvum ◽  
Giardia Duodenalis ◽  
Cryptosporidium Parvum Oocysts

Direct counting of Cryptosporidium parvum oocysts using fluorescence in situ hybridization on a membrane filter

2006 ◽  
Vol 67 (2) ◽  
pp. 373-380 ◽  
Author(s):  
Tomoyuki Taguchi ◽  
Youhei Shinozaki ◽  
Haruko Takeyama ◽  
Satoshi Haraguchi ◽  
Masato Yoshino ◽  
...  
Keyword(s):  
In Situ Hybridization ◽  
Fluorescence In Situ Hybridization ◽  
Cryptosporidium Parvum ◽  
Membrane Filter ◽  
Direct Counting ◽  
Cryptosporidium Parvum Oocysts

Effects of ozonation and chlorination on viability and infectivity of Cryptosporidium parvum oocysts

2000 ◽  
Vol 41 (7) ◽  
pp. 39-46 ◽  
Author(s):  
T. Hirata ◽  
D. Chikuma ◽  
A. Shimura ◽  
A. Hashimoto ◽  
N. Motoyama ◽  
...  
Keyword(s):  
Cryptosporidium Parvum ◽  
Experimental Studies ◽  
Free Chlorine ◽  
Log Reduction ◽  
Cryptosporidium Parvum Oocysts ◽  
Permeability Assay

Experimental studies on ozonation and chlorination were conducted to determine capacity for inactivating Cryptosporidium parvum oocysts in batch modes at pH 7, 20°C. In both experiments, the log reduction of animal infectivity was linear and clearly decreased as disinfectant CT product increased. However, the curve of reduction in viability determined by both in vitro excystation assay and DAPI/PI permeability assay exhibited a shoulder. The CT products of ozone per 1 log reduction in infectivity were 3 mg middot min/L for 0.5 mg/L and 1.5 mg · min/L for 0.3 mg/L, while viability determined by in vitro excystation was reduced by only 0.2 logs for the CT product of 3 mg · min/L. In the chlorination experiment, thereduction of animal infectivity was up to 3 logs for the CT product of 2,700 mg middot; min/L, while reduction of viability was smaller at 0.16 logs in in vitro excystation and 0.04 logs in DAPI/PI permeability (in PI exclusion) for the same CT product. The CT product of free chlorine per 1 log reduction in infectivity was estimated to be in the range of 800 to 900 mg · min/L.

Sign in / Sign up

Export Citation Format

Share Document