Host Disease Tolerance Predicts Transmission Probability for a Songbird Pathogen.

Area of Science:

• Ecology
• Evolutionary Biology
• Disease Ecology

Background:

• Disease tolerance is crucial for host adaptation, minimizing infection costs.
• Mechanisms of disease tolerance, such as tissue-specific and behavioral tolerance, vary.
• The impact of different tolerance mechanisms on host transmission potential remains unclear.

Purpose of the Study:

• To investigate how tissue-specific and behavioral tolerance affect disease transmission in house finches.
• To assess the role of these tolerance mechanisms in the context of Mycoplasma gallisepticum (MG) infection.
• To understand the implications for host-pathogen coevolution and epidemic dynamics.

Main Methods:

• Inoculated wild-caught house finches from populations with varying tissue-specific tolerance to MG.
• Assessed transmission likelihood from infected "index" birds to susceptible cagemates.
• Quantified pathogen load and observed host behavior, including feeder use.

Main Results:

• House finches with higher tissue-specific tolerance showed reduced MG transmission.
• Reduced conjunctivitis in tolerant birds correlated with decreased pathogen spread.
• Behavioral tolerance did not significantly influence the likelihood of MG transmission.

Conclusions:

• Tissue-specific disease tolerance mechanisms can decrease pathogen transmission rates.
• Behavioral tolerance may not directly impact transmission dynamics in this system.
• Differentiating tolerance mechanisms is essential for predicting host-pathogen interactions and disease spread.