Analysis of sampling strategies to substantiate freedom from disease in large areas

Concepts for risk-based surveillance in the field of veterinary medicine and veterinary public health: Review of current approaches

“…Issues to be considered in non-risk-based sampling such as test performance and clustering (Martin et al, 1992;Cameron and Baldock, 1998aand 1998b, Ziller et al, 2002 are equally relevant in risk-based sampling.…”

Using Auxiliary Information to Improve Wildlife Disease Surveillance When Infected Animals Are Not Detected: A Bayesian Approach

“…Although the term freedom-from-disease is commonly used in this sampling setting [7],[8],[9], it is a misnomer from the statistical point of view. What is usually actually meant is that disease prevalence π is ascertained to be below some designated target threshold π t with some level of “assurance” (we elaborate on what this means later).…”

“…What is usually actually meant is that disease prevalence π is ascertained to be below some designated target threshold π t with some level of “assurance” (we elaborate on what this means later). Indeed, policy may allow an area to be declared “free from disease” even if disease is observed to be present, but at an acceptably low level(e.g., [7]). Determining what target prevalence level π t is acceptably low for an area to be deemed disease-free is a case-by-case policy issue (see [3]) which we do not address; our concern is in efficiently determining whether the true prevalence π is less than the target threshold π t with an appropriate degree of statistical assurance.…”

Molecular diagnostic investigation of brucellosis in a caprine organic farm

“…Although the sensitivity of PCR is usually high, the uneven distribution of the bacterium and the fact that in most cases it does not circulate in the blood of carrier animals (Ziller et al, 2002) demonstrate an interesting aspect of the finding mentioned above, since it refers to clinically healthy goats found at a state of bacteraemia. This seems to agree with the concept that goats consist a brucellosis reservoir in Greece, developing a milder disease than sheep and preserving the infection for longer periods of time (Papadopoulos 1992).…”

“…This was also supported by the fact that serology evaluation of test samples, although interesting, would not be easily interpreted (Reviriego et al, 2000) considering the prevalence of ρείς Brucella με μικροβιακό φορτίο αρκετά υψηλό ώστε να γίνει ταυτοποίηση του βακτηρίου με μια μόνο δειγ ματοληψία αίματος. Αν και η ευαισθησία της PCR εί ναι συνήθως υψηλή, η ανομοιόμορφη κατανομή του βακτηρίου και το γεγονός ότι αυτό δεν κυκλοφορεί συνήθως στο αίμα σε ζώα φορείς (Ziller et al, 2002) καταδεικνύει μια ενδιαφέρουσα παράμετρο του πα ραπάνω ευρήματος δεδομένου ότι αφορά σε ζώα κλι νικά υγιή, που βρίσκονται ταυτόχρονα σε φάση βα κτηριαιμίας. Το εύρημα αυτό φαίνεται να συμφωνεί με την αντίληψη ότι δεξαμενή της βρουκέλλωσης στην Ελλάδα είναι οι αίγες που νοσούν πιο ελαφρά από τα πρόβατα και συντηρούν τη λοίμωξη για μακρό χρονι κό διάστημα (Παπαδόπουλος 1992).…”