What is periodicity of filarial worms?

The lymphatic filarids Wuchereria bancrofti, Brugia malayi and B. timori produce microfilariae that usually appear in the blood between 2200 and 0200 hours (nocturnal periodicity). W. bancrofti found in some Pacific Islands produce microfilariae that appear in the blood in the daytime (diurnal periodicity).

What is the periodicity of microfilaria?

The behaviour of microfilariae is adapted to promote transmission by arranging the maximum number of microfilariae in the peripheral blood at times when the arthropod vector is likely to bite. The most sophisticated arrangement to achieve this is by a 24 h rhythm—the classical ‘periodicity’.

What is nocturnal periodicity in parasitology?

The microfilariae that cause lymphatic filariasis circulate in the blood at night (called nocturnal periodicity). Blood collection should be done at night to coincide with the appearance of the microfilariae, and a thick smear should be made and stained with Giemsa or hematoxylin and eosin.

What is Subperiodic periodicity?

a modified circadian rhythm in which the periodicity is not clearcut, as in certain zoonotic strains of Malayan filariasis caused by Brugia malayi; as in examples of strict filarial periodicity, this response is correlated with the biting habits of the vector insect (mosquito), although the precise mechanism inducing …

What is a sheathed microfilaria?

In most blood-dwelling species, embryonated eggs (or, microfilariae which are said to be sheathed in the envelope of the egg) are released; and they will only exsheath (“hatch”) after being ingested by the arthropod intermediate host. Many of the organs of microfilariae are in a very early stage of development.

What is meant by nocturnal periodicity?

Nocturnal periodicity is exhibited by microfilarial larva of wuchereria bancrofti. It is a circadian rhythm with the periodicity expressed during night time. It is less active in day blood. It is highly found in the circulation at night. It is found in regions where the vector mosquito is a night-biting species.

Why is there nocturnal periodicity of microfilariae?

Microfilariae are less active in day blood than in night blood. It is suggested that because of this, they are not able to work their way through the capillaries in the daytime, hence the mechanism of nocturnal periodicity.

What is microfilaria test?

A microfilaria test involves examination of the blood smear to identify the existence of microfilariae in blood. Usually, a microfilariae blood test is conducted at night to coincide with the appearance of microfilariae.

What does Subperiodic mean?

Filters. (biology) Describing a circadian rhythm that is not precisely periodic.

What is meant by microfilaria?

A microfilaria pertains to the embryonic or early larval stage of a filarial worm or of related genera of the family Onchocercidae. It includes parasitic worms of humans such as those causing filariasis, onchocerciasis, loiasis, etc. The microfilaria develops from the egg.

Where are microfilaria found?

Microfilaria is an early stage in the life cycle of parasitic nematodes in the family Onchocercidae. The adults live in tissues and circulatory system of vertebrates. They release microfilariae into the bloodstream of the vertebrate host. The microfilariae are taken up by blood-feeding arthropod vectors.

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