Aquatic pathogens are important both in terms of animal welfare and economically for both aquaculture and capture fisheries. However, mathematical modelling of microparasites has focussed almost exclusively on terrestrial pathogens. One of the key assumptions of these models is the form of the transmission term. In this presentation we explore the hypothesis that transmission mechanisms in water will be different to those in terrestrial systems.

Viral haemorrhagic septicaemia (VHS) is an important virus which affects rainbow trout (Oncorhynchus mykiss). It has a significant impact on the trout industry worldwide, with VHS costing an estimated £10.3-31 million per year in Europe. Currently the UK is free of VHS, but should it re-enter the UK, knowledge of how it may spread is vital to reducing the overall impact.

In this presentation we will consider three different types of disease transmission, look at their impact on long term behaviour and, using data, determine which one is the most realistic one to use to describe VHS transmission. We will then discuss the results in the context of aquatic pathogens more generally.