Knowledge of nocturnal periodicity is especially important in diagnosing infections caused by which organism group?

• A. Microfilariae
• B. Plasmodium
• C. Babesia
• D. Trypanosoma

Answer: (A)

Nocturnal periodicity is when certain microfilariae circulate in peripheral blood predominantly at night. This pattern matches the feeding times of the mosquito vectors that transmit filarial infections, so collecting blood during the night increases the likelihood of detecting the parasites. Among the listed organism groups, microfilariae are the ones known for this nighttime surge in blood, making nocturnal timing a key diagnostic aid for infections such as bancroftian and Brugian filariasis. Other organisms shown have different patterns of presence in blood (for example, malaria parasites cause fever cycles tied to their replication, not a predictable nightly circulation; Babesia and Trypanosoma have other parasitemia patterns), so the nocturnal blood-detectable presence is most characteristic of microfilariae.