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EFFECT OF LOT VARIABILITY ON ULTRAVIOLET RADIATION INACTIVATION KINETICS OF CRYPTOSPORIDIUM PARVUM OOCYSTS
Citation:
SIVAGANESAN, MANO AND S. SIVAGANESAN. EFFECT OF LOT VARIABILITY ON ULTRAVIOLET RADIATION INACTIVATION KINETICS OF CRYPTOSPORIDIUM PARVUM OOCYSTS. Jerald Schnoor (ed.), ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, 39(11):4166-4171, (2005).
Description:
The primary goal of this paper is to account for the effect of lot variability in determining the required ultraviolet (UV) radiation to inactivate Cryptosporidium parvum oocysts in mouse infectivity studies. The number of infectious oocysts (infective dose) per mouse is estimated via a logistic dose response model. As the error in estimating the infective dose can affect the required UV radiation to obtain a certain inactivation level, a weighted linear regression analysis is used to model the log-inactivation as a function of UV. Since the proportion of infected mice can be zero or one, the estimated infective dose may contain right or left censored data. A hierarchical Bayesian modeling approach is used in this paper, which provides a robust method for incorporating censored data. As the inactivation rate may depend on the lot of oocysts, the lot variability is incorporated as a random factor. Posterior distributions are used to estimate the mean, median and 100(1-a)% confidence interval (CI) for the required UV radiation to achieve a given inactivation level of Cryptosporidium parvum oocysts.