Myxomatosis: the Introduction of a Highly Virulent Strain of Myxomatosis Into a Wild Rabbit Population at Urana in New South Wales.

Abstract

A site of 280 ha at Urana had four discrete rabbit populations. In September 1977 fleas, Spilopsyllus cuniculi, were used to successfully introduce a highly virulent strain (Lausanne) of myxoma virus into two of the populations; the other two were untreated. Eight weeks after virus introduction, rabbits infected with the Lausanne strain were found on the two largest warrens in one of the untreated areas. A field-strain epidemic reached most of the other warrens in the untreated areas in the summer months. Eighteen weeks after the introduction of the Lausanne strain, 1% of the 738 susceptible animals on warrens in the Lausanne-strain areas, 3% of the 328 on warrens in the field-strain areas, and 14% of the 29 on peripheral warrens that escaped myxomatosis had survived. The low rainfall, 25% of average in the second half of 1977, affected pasture production and led to the deaths of almost all rabbits born late in the season. Repeated annual introductions of the Lausanne strain in non-drought years will be necessary to determine the effectiveness of this procedure in reducing recruitment to the breeding population.