The role (and evolution of) rhythms in infections

An unexplained phenomenon in malaria infections is that all parasites within a given host (millions of them) progress through their cell cycle synchronously. In other words, the parasites individually infect host RBCs, replicate, and burst out of those cells simultaneously. This astonishing coordination has long been recognised, yet there is almost no understanding of what controls this scheduling or why it would have evolved in the first place. There exist a number of potential adaptive explanations for the coordinated development of malaria parasites, largely inspired by developmental rhythms in other parasites, plants, and animals.

Some of the most persuasive hypotheses, with existing corroborating evidence, invoke rhythms in host physiology (e.g., host immune responses) as a driving factor of the coordinated development of malaria parasites. We’re using mathematical models to test the plausibility of these hypotheses — asking whether rhythms in hosts could drive the evolution of rhythms in parasites, or vice-versa.

Relevant papers:

O’Donnell, A.J., Mideo, N., & Reece, S.E. (2013) Disrupting rhythms in Plasmodium chabaudi: costs accrue quickly and independently of how infections are initiated. Malaria Journal, 12: 372.PDF

Mideo, N., Reece, S.E., Smith, A.L., & Metcalf, C.J.E. (2013) The Cinderella Syndrome: Why do malaria-infected cells burst at midnight? Trends in Parasitology, 29: 10-16. PDF