Roadmap for the development of control strategies for liver fluke

What are we trying to achieve and why? What is the problem we are trying to solve?

The role of the intermediate host in maintaining and transmitting infection.

What are the scientific and technological challenges (knowledge gaps needing to be addressed)?

• Do parasites differ in their virulence for the intermediate host?
• The development of biological and other alternative control methods for the snail.
• Host range of the parasite and ability to use alternative snail species in different parts of the world and different
  environments to expand endemic areas.
• Competition within and between trematode species for resources within the snail and outcomes for fluke transmission.
• Knowledge of snail-parasite interactions is essential to predict how snails will adapt to infection pressure and altered management.
• Impact of climate change on snail biology/adaptation to different environments

What approaches could/should be taken to address the research question?

• Better understanding of basic snail biology.
• Resumption of work on basic population dynamics of snails.
• Integration of studies on fluke intermediate hosts with ecological theory and practice.
• Development and application of novel molecular tools to better understand heterogeneity in snail-parasite interactions and its implications.
• Experimental approaches to snail defence and parasite strategies for overcoming them.

What else needs to be done before we can solve this need?

• Knowledge of the impact of environmental factors on the vector.
• Methods for determining infection levels in snails.
• Improved knowledge of snail-Fasciola interaction.

Existing knowledge including successes and failures

• After basic work on transmission processes, much knowledge of the role of the intermediate host in fluke transmission relies on correlation of environmental factors with disease challenge in livestock, with snail populations implicated as the causative link.
• Quantifying the processes at play is essential to upgrade predictive epidemiological understanding.
• Understanding these processes in more detail might also allow more effective use of environmental and alternative control approaches, including biological control.
• The effects of diversity in snail hosts on transmission potential has been explored but mainly at species level and not finer scales (between and within populations of the same snail species).