Clockwork intruders: Do parasites manipulate their hosts' circadian rhythms?

Area of Science:

• Chronobiology
• Parasitology
• Behavioral Ecology

Background:

• Circadian clocks regulate biological processes in most organisms.
• Parasites have evolved to exploit host circadian rhythms for their own benefit.
• Examples include parasites altering host behavior to facilitate transmission or optimize life cycles.

Purpose of the Study:

• To review the phenomenon of parasitic manipulation of host circadian rhythms.
• To highlight the diverse strategies parasites employ to alter host behavior and physiology.
• To emphasize the need to differentiate between parasite manipulation and host response.

Main Methods:

• Literature review of studies on parasites affecting host circadian rhythms.
• Analysis of examples across various parasite taxa (fungi, protozoa, helminths).
• Discussion of proposed mechanisms, including changes in clock-controlled gene expression.

Main Results:

• Parasites like Microphallus, Trypanosoma cruzi, Ophiocordyceps, Entomophthora, and Plasmodium alter host behavior and physiology.
• Behavioral modifications can promote parasite transmission and optimize life cycle completion.
• Changes in host circadian rhythms can result from direct manipulation or host responses like inflammation.

Conclusions:

• Parasitic manipulation of circadian rhythms is a significant and understudied phenomenon.
• Distinguishing between parasite-driven manipulation and host responses is crucial for future research.
• Further understanding could lead to novel therapeutic strategies against parasitic diseases.