Crypto-periodicity in Mansonella ozzardi

Summary Studying nycthemeral microfilarial density in eight carriers of Mansonella ozzardi, Nathan et al. concluded that there is an absence of periodicity in M . ozzardi in Trinidad. Re-examination of the results obtained shows evidence of crypto-periodicity. Two of the eight patients showed highly significant periodicity but the biorhythms appear to be almost out of phase, the respective peaks being at 18.00 hours and 02-Whours. The six other patients showed no obvious periodicity; the calculated acrophases (peak hours), instead of being randomly spaced, regrouped with the preceding ones: late afternoon in two subjects and in the second half of the night for the other four. It is concluded that the apparent non-periodicity is due to the Co-existence of two periodic forms, but these are markedly out of phase