SUMMARYThe virulence of field strains of myxoma virus is increasing in the Mallee region of Victoria where the resistance of the rabbit to myxomatosis is high. This suggests that the climax association will be a moderately severe disease.

SUMMARYSera from 823 wild rabbits (Oryctolagus cuniculus) collected from a number of geographic regions of Victoria, Australia over the past eight years were examined for antibodies to Encephalitozoon cuniculi, along with sera from 46 hares (Lepus europaeus) (Pallas) and 57 New Zealand wild rabbits. No sera were positive, implying that this common laboratory rabbit parasite is absent from wild rabbits in these areas. However, wild rabbits were found to be readily infected by the oral route with small numbers of tissue-culture-grown spores of E. cuniculi. A possible explanation for the absence of encephalitozoonosis in wild rabbits is that E. cuniculi infection places them at a biological disadvantage for survival. The natural hygiene habit of wild rabbits may also significantly decrease post-natal infection.

SUMMARYSharp reductions in the wild rabbit (Oryctolagus cuniculus (L.) This reduction occurs in a population which is the most resistant to myxomatosis known in Victoria and in association with epizootics caused by field strains of myxoma virus of moderate virulence only.The earlier summer epizootics are of considerable economic importance because they sharply reduce the pressure on the limited food available for other grazing animals.

SummarySera or serum eluates from 1697 wild rabbits [Oryctolagus cuniculus (L)], collected over the past 10 years from 24 sites in 5 geographic regions of Victoria, were examined for antibodies to Toxoplasma gondii. Sera generally were classified into three broad groups, negative (titre < 10), weakly reactive (titre 10 to 100) and strongly positive (titre > 1000). Strongly positive sera came from rabbits collected in a small number of localized areas, most significantly the Melbourne and Metropolitan Board of Works (MMBW) Sewerage Farm at Werribee and Mud Island in Port Phillip Bay.

SummaryThe response of wild and domestic rabbits with a degree of genetic resistance to myxomatosis has been shown to be markedly affected by the age at which they were infected with a virulent strain of the virus. The response, in terms of mean survival time and percentage survival, fell with increasing age from 10 to 30 weeks with little change thereafter.