Sleeping sickness is a circadian disorder.

Area of Science:

• Parasitology
• Chronobiology
• Neuroscience

Background:

• Sleeping sickness, a fatal disease caused by Trypanosoma brucei, presents with altered sleep/wake cycles, but the mechanisms remain unclear.
• Circadian rhythms regulate physiological processes, and their disruption can lead to various health issues.

Purpose of the Study:

• To investigate the impact of Trypanosoma brucei infection on host circadian rhythms.
• To determine if the parasite directly affects the host's internal clock.

Main Methods:

• Mice were infected with Trypanosoma brucei, and their activity patterns were monitored to assess circadian rhythm phase.
• Circadian period was measured at behavioral, tissue, and cellular levels.
• Explants and fibroblasts were co-cultured with the parasite to assess direct effects on clock period.
• Malaria infection was used as a control to determine specificity.

Main Results:

• Trypanosoma brucei infection caused a phase advance in the circadian rhythms of mice, leading to abnormal activity during rest periods.
• Circadian period shortening occurred at behavioral, tissue, and cellular levels.
• Period shortening was specific to Trypanosoma brucei and independent of the host immune response.
• Co-culture experiments confirmed direct parasite-induced period shortening, which was not observed with malaria infection.

Conclusions:

• Trypanosoma brucei infection induces an advanced circadian rhythm disorder in the host.
• This disorder, characterized by period shortening, leads to altered sleep timing.
• The findings suggest a novel mechanism by which parasites disrupt host physiology.