Co-circulation and co-infection: parasite interactions across scales

Area of Science:

• Ecology
• Epidemiology
• Evolutionary Biology

Background:

• Parasite-parasite interactions are crucial in disease ecology but are often studied at single scales (within-host or between-host).
• This fragmented approach limits understanding of integrated ecological effects and evolutionary drivers in multi-parasite systems.

Purpose of the Study:

• To extend the susceptible-infected (SI) epidemiological framework to explicitly incorporate parasite-parasite interactions across multiple scales.
• To identify specific points in the transmission process where within- and between-host interactions occur.
• To provide a unified framework for analyzing the evolutionary ecology of multi-parasite systems.

Main Methods:

• Theoretical extension of the standard susceptible-infected (SI) epidemiological model.
• Identification of interaction points across host infection and transmission stages.
• Inclusion of empirical examples to illustrate theoretical concepts.

Main Results:

• Parasite-parasite interactions can occur at multiple stages of the transmission cycle, both within and between hosts.
• Integrating across-scale interactions provides a more holistic view of disease dynamics.
• The extended SI framework offers a tool for analyzing complex multi-parasite systems.

Conclusions:

• Considering parasite-parasite interactions at both within- and between-host levels is essential for accurate ecological and evolutionary predictions.
• The developed theoretical framework facilitates a deeper understanding of the evolutionary ecology of hosts and parasites.
• Future research should focus on empirical validation and further refinement of multi-scale interaction models.