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    Cryptosporidium parvum oocyst viability and behaviour of the residual body during the excystation process
    (Springer, 2011) Kar, Sırrı; Daugschies, Arwid; Çakmak, Ayşe; Yılmazer, Nadim; Dittmar, Katja; Bangoura, Berit
    This study was conducted as a comparative evaluation of time-dependent changes in the viability of purified Cryptosporidium parvum oocysts by means of different excystation methods. Oocyst samples were 2 weeks to 12 months old and were treated with bile or sodium taurocholate, partly after pretreatment with hypochlorite. Pretreatment markedly enhanced the excystation of younger oocyst samples but did not increase excystation rates of 9 or 12-month-old oocysts. A cell culture-PCR assay was used as a second indicator for oocyst viability and was most consistent with excystation trials including oocyst pretreatment. In experiments aiming at the determination of the behaviour of the oocyst residual body during excystation, it could be demonstrated that it might be involved in this process.
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    Quantitative comparison of different purification and detection methods for Cryptosporidium parvum oocysts
    (Elsevier Science Bv, 2011) Kar, Sırrı; Gawlowska, Sandra; Daugschies, Arwid; Bangoura, Befit
    Cryptosporidium parvum (C. parvum) is the causal agent of cryptosporidiosis in many animals, mainly cattle, and possesses a high zoonotic potential. It occurs worldwide and ubiquitously. Detection of C. parvum is mainly performed directly but purification of the oocysts is useful to increase sensitivity and to obtain oocyst material for further use. The study was designed to compare (a) three different direct diagnostic methods, namely modified Ziehl-Neelsen staining, carbol fuchsin staining and conventional PCR, and (b) three routine oocyst purification methods, in particular flotation with saturated sodium chloride solution, Sheather's sucrose solution and a Percoll gradient. During comparison of purification methods, special regard was paid to the ability to separate morphologically intact oocysts from the morphologically degenerated fraction or viable from non-viable oocysts, respectively. Results: (a) Diagnostic methods: Most effective in C. parvum oocysts detection in calf faeces was PCR; carbol fuchsin and modified Ziehl-Neelsen stainings achieved comparable results. (b) Purification methods: Oocyst flotation using sodium chloride solution showed to be superior to Percoll gradient centrifugation and sugar flotation in terms of purification quality, recovery efficacy (yield) and reduction of the proportion of degenerated or non-viable oocysts. (C) 2010 Elsevier B.V. All rights reserved.