A winter epizootic of myxomatosis in subalpine south-eastern Australia

Abstract

An epizootic of myxomatosis in rabbits that occurred during the winter months (March-August) of 1969 is described in detail. Virus of virulence grade 111, the common virulence of field strains of myxoma virus presently in Australia, was isolated during the epizootic. The estimated case mortality was 86% over the 5 months during which the epizootic was active. Only 41228 of the original susceptible and established population completely avoided infection. Transmission through the population was relatively slow and apparently depended on social contact between individual rabbits. The seasonal conditions and the slow progression of the disease through the population make it most unlikely that mosquitoes were involved in transmitting the virus. The origin of the virus that initiated the epizootic is discussed, including the possibility that it was not a reintroduction of myxoma virus to the population. This implies that the virus may have remained latent in the rabbit population for several years.