Synchronicity Index

Synchronour development of parasites In some malaria infections (particularly with Plasmodium falciparum or with Plasmodium knowlesi) there may be only a single parasite stage visible in blood – this is most often early trophozoites. This process is partly a reflection of the interesting phenomenon of “synchronicity” of parasite development. IMAGE While the precise reasons and mechanisms of synchronicity are not fully clear, the biological effects can be clearly seen in some cases where the stages of invasion of erythocytes, their asexual replication, then their escape from schizonts each occur in unison. The process appears to reflect the circadian rhythms of the host both in gene expression and in behaviour and results in parasites in the blood reflecting only a single stage. It is thought that fevers in malaria correspond to the sudden antigen load seen during schizont release IMAGE. When schizont release is synchronous this can lead to the recognised phenomena of periodic fevers in malaria e.g. in P. falciparum infection untreated individuals may exhibit fever cycles, with a 48-hour cycle so the periodicity of fever is tertian (“tertian malaria”), whereas in P malariae disease, fever occurs every 72 hours (“quartan malaria”). This is not absolute with some infections appearing synchronous and others