Risk of introduction of Newcastle disease in Chile through import of ostriches

Abstract

Chile has been free of Newcastle disease (ND) of type PMV- 1 since 1977. The objective of this study was to evaluate the risk of introduction of ND into Chile through importation of ostriches using a stochastic simulation model. Data for the model input were obtained from bibliographical sources and sanitary information published by animal health institutions. A scenario tree model incorporated the ND prevalence in ostriches in the exporting countries, the number of ND infected ostriches exported and the sensitivity of the tests before exportation and during quarantine in Chile. The outcome variable was the number of ND infected ostriches (per year) that enter Chile after quarantine. The model was simplified by limiting the model to two types of countries that represented countries of which Chile imported most ostriches: a ND-free country and a country where ND was endemic. The number of positive ostriches that enter Chile was strongly related to the number of outbreaks in the endemic country and the number of imported ostriches from the endemic country and amounted 2.2 ^x 10^–5 with an upper 90% CI limit of 8.5 ^x 10^–5 per year. The scenario tree model was a simplification of reality and the risk of introduction of ND in Chile by importation of ostriches was very low even in worse case scenarios.