The thermal tightrope of infection: why a parasite thrives in the cold
A study of a mosquito-parasite system reveals a counterintuitive, nonlinear effect of temperature on infection success. Researchers paired field surveys across a 12°C climate gradient with lab experiments to map thermal performance curves for the ciliate parasite Lambornella clarki infecting its mosquito host. They found that infection rates peaked at surprisingly cold temperatures (8.4–10°C), a result consistent between the field and the lab. This peak occurs because, while warmer temperatures favor parasite growth, they also trigger a stronger melanization immune response in the host. The balance between these opposing forces creates an optimal thermal window for parasitism that is cooler than the parasite’s preferred free-living conditions.
Why it might matter to you:
This work provides a precise mechanistic framework for understanding how temperature shapes host-pathogen dynamics, a core concept in immunology and vaccine research. For someone investigating immune evasion or adjuvant strategies, it highlights how environmental variables can critically alter the balance between pathogen fitness and host defense efficacy. The methodology of constructing thermal performance curves for specific immune and pathogen traits could be adapted to model how climate affects diseases of greater clinical or conservation concern.
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