Microfilariae, which are the larvae of filarial worms show a nocturnal periodicity of entering into blood in south Asia and China. This coincides with the biting habits of its vector. The same very species in Malaysia, the larvae are present throughout the day and night but peak at specific time points (subperiodic). The vector there hase different feeding habits.
This understandably is beneficial to the worm.
What are the cues that the worm uses to understand day and night?
Reversing the sleep wake cycle also apparently reverses the periodicity of the larvae from nocturnal to diurnal.