An examination of multiple components of emotional processing theory as predictors of symptom change in prolonged exposure for posttraumatic stress disorder
Date
2022
Authors
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Publisher
University of Delaware
Abstract
Cyclospora cayetanensis is a lesser studied member of the Apicomplexan family of protozoa, which includes more well studied protozoan genera like Cryptosporidium, Eimeria, and Toxoplasma. However, C. cayetanensis is an important protozoan parasite that continues to cause outbreaks of gastroenteritis associated with contaminated fresh produce. Cyclospora oocysts may be transmitted through contaminated surface water, thereby making reliable detection imperative for public health and produce safety. Cyclospora is still considered an emerging pathogen by many, due to the limited understanding and large data gaps surrounding the transmission and survival of oocysts in the environment limitations in detection of oocysts. Polymerase chain reaction (PCR) analysis is used for detection of a presumptive positive water sample. Filtration using the ZVI-sand filtration achieved a 4.30-log reduction of Cryptosporidium parvum compared to 1.82 log reduction using sand filtration. When comparing the two filtration systems, there was a significant difference in efficacy (p < 0.05) with ZVI-sand filtration yielding larger reductions of C. parvum oocysts. For reduction of Eimeria tenella oocysts, ZVI-sand filters achieved a 6-log reduction, whereas sand-only filtration achieved a 2.3-log reduction. There was a significant difference (p < 0.05) in ability to inactivate and remove E. tenella oocysts, the ZVI-sand filtration performed better compared to the sand alone filtration. This study investigated the effects of gaseous chlorine dioxide at varying treatment times on Cryptosporidium parvum on produce, baby cut carrots and grape tomatoes. Grape tomatoes (approx.40g) and baby-cut carrots (approx. 35g) were spot inoculated (106 oocysts) with 100-µl of C. parvum suspension in 10-µl droplets randomly distributed on the produce samples. Inoculated produce samples were treated with 50 g of each gaseous chlorine dioxide precursor for 0, 1 and 3 hours in a 35-L enclosed chamber. Significant reductions were shown at both 1 hour and 3-hour treatment times for both produce types. The results of this work will facilitate the development of novel on-farm filtration technology and guidelines for commercial applications to control parasitic pathogens in agricultural water, thus improving the safety of produce and control of protozoa in agricultural water. A total of seventy-two water samples were collected regularly from various sites in Delaware and Maryland over the course of 17 months (June 2017-October 2018). DNA Primer Sequences for Cryptosporidium Genus-specific PCR Amplification (18S rRNA) used, followed by further testing using VspI and DraII restriction fragment length polymorphism enzyme for speciation confirmation. The nested PCR amplicons were digested with one unit of VspI for distinction between C. parvum and C. hominis. For distinction of C. parvum, C. baileyi and C. serpenti, the nested PCR amplicon were digested with one unit DraII. Twenty-four out of seventy-two water samples were confirmed to contain Cryptosporidium parvum. Through further testing using restriction fragment length polymorphism analysis, one water sample was confirmed to harbor C. cayetanensis or E. neischulzi, which have genetic similarities to Cryptosporidium species. A single sample was identified to be either C. baileyi or C. serpenti, which do not infect humans. Knowledge of parasitic organisms in potential irrigation water sources are essential for correct implementation of water testing and water treatment.
Description
Keywords
Cryptosporidium parvum, Cyclospora cayetanensis, Protozoa, Toxoplasma, Polymerase chain reaction