| Amphibian species are in decline around the globe and infectious diseases are thought to be a large contributor to these declines. The Ranaviruses, a group of viruses belonging to the Iridoviruses, are emerging infectious diseases in amphibian populations. The Ranavirus has been associated with mass mortality events in ranid tadpoles in Ontario. This thesis examines the progression of Ranaviral infections in the wild in three aquatic amphibian communities. It is the first study to examine the presence of Ranaviral infections in multiple amphibian species in the same physical space. The mode of transmission of frog virus 3, a Ranavirus, is also examined in wood frog (Rana sylvatica) tadpoles. It was found that both vertical and horizontal transmission of a Ranavirus could occur.;The effect of exposure to both frog virus 3 and an immunosuppressant pesticide, Malathion, was examined in both wood frog and bullfrog ( Rana catesbeiana) tadpoles. This study supports the immunosuppression hypothesis. When assessing the mortality, as well as the abnormal behaviour data, it appears that the effects of combined exposure to an immunosuppressant and an infectious disease was more severe than in either treatment alone. From the field data, the information about the mode of transmission, and the immunosuppression data, a model of viral transmission for the Ranavirus in aquatic amphibian communities is proposed. |
