The periodicity of microfilariae X. the relation between the circadian temperature cycle of monkeys and the microfilarial cycle

Abstract

Monkeys were used whose blood contained the microfilariae of Edesonfilaria malayensis, which has a nocturnal periodicity. Artificial lowering of the body temperature during the daytime caused the microfilaria count in the blood to rise; and artificial raising of the body temperature during the night caused it to fall almost to zero, i.e. inversion of the normal circadian temperature rhythm of the body was followed by inversion of the microfilarial rhythm. The hypothesis is put forward that the circadian rhythm of the microfilariae of E. malayensis (but probably not of the microfilariae of some other species) is entrained by the circadian rhythm of body temperature, which thus provides the “effective stimuli” to which these microfilariae respond.