Wuchereria bancrofti- Habitat, Morphology and Life Cycle
Table of Contents
Systematic Position of Wuchereria bancrofti
Habits and Habitat of Wuchereria bancrofti
1. Adult worms
2. Microfilaria
Periodicity of Microfilariae
3. Third stage of the larva (infective form)
Life cycle of Wuchereria bancrofti
a. Copulation
b. Larval development in man
c. Development in mosquito
d. Infection of the new human host
References and Sources
Systematic Position of Wuchereria bancrofti
Phylum: Nematoda
Class: Phasmidia
Order: Filaroidea
Family: Filariidae
Genus: Wuchereria
Species: bancrofti
Habits of Wuchereria bancrofti and Their Environment
The filarial worm, Wuchereria bancrofti, is a human endoparasite that is
feared.
It is a digenetic parasite that need two hosts to complete its life cycle. The
intermediate host is bloodsucking insects, such as female mosquitoes of
the genus Culex, Aedes, or Anopheles, while the final host is man, who
harbors the adult worms.
Adult worms dwell coiled up in the human lymphatic system, where they
frequently block the lymphatic movement.
The larvae, also known as microfilariae, are discovered in peripheral blood
and, on occasion, in hydrocele fluid or chylous urine.
Morphology of Wuchereria bancrofti
1.adults worm
These worms are long, hair-like, translucent, transparent, thread-like, tapering-ended, and
have smooth cuticles.
They are cylindrical, filiform, and taper at both ends.
There is a clear sexual dimorphism between the sexes.
Compared to the male (25-40 × 0.1 mm), the female is bigger (70-100 × 0.25 mm).
The male worm has a vertically curved rear end with two copulatory spicules of uneven
length and numerous genital papillae, while the female worm has a narrow, pointed
posterior end with an anus.
Typically, males and females stay coiled together in the testicular tissues, inguinal
lymphatics, and abdominal lymphatics.
It has a somewhat larger head end.
There are no lips and a plain mouth opening.
An anterior muscular portion and a posterior muscular section make up the pharynx.
The female's vulva has a pyriform ejector mechanism and is situated ventrally in the
pharyngeal area.
Sheathed microfilariae are released into the lymph by the viviparous female worm.
Adult worms typically live for ten to fifteen years or longer.
2. Microfilaria
Microfilaria are the larvae at their first stage.
Their bodies are transparent and colorless, with pointed tails and blunt front ends.
They may travel forward and backward within the sheath, which is significantly longer
than the embryo, and are highly active.
They are minuscule, with dimensions of 6-10 μm for thickness and 250-300 μm for
length.
A hyaline sheath covers its body, and then a cuticula lined with flattened subcuticular
cells or epidermis and an inner column of cytoplasm with nuclei follow. It has distinct
striations on its cuticle.
With the exception of the 5% terminal end of the tip, somatic cella or nuclei appear as
granules in the body's central axis that extends from head to tail.
Their head-end features cephalic space, which is a clean area free of granules.
Future mouth or oral stylet, nerve ring: oblique area without granules, nephridiopore,
renette cell, dark-colored inner mass, and four cells of the future anus are important
structures from the anterior end downward.
Unless they are ingested by their appropriate host (mosquitoes), they do not continue to
develop within the human body.
They most likely have a 70-day lifespan in the human body.
Periodicity of Microfilariae
The bloodstream is where the microfilariae move.
They exhibit a nocturnal periodicity in peripheral circulation in China, India,
and many other Asian nations. They are only observed in significant
quantities in peripheral blood at night (between 10 p.m. and 4 a.m.), but they
vanish indoors during the day. They are thought to withdraw into the deeper
blood artery throughout the day. This is consistent with the vector Culex
mosquito's propensity to bite at night.
The microfilariae are diurnal subperiodic or nonperiodic in the Pacific
islands and sections of the Malaysian archipelago, meaning they are
constantly in peripheral circulation with a modest peak in the late afternoon
or evening. This relates to the behavior of day-biting of the local vactor
mosquito
3. The infectious form of the larva's third stage
The parasite's infectious third stage larva is exclusively found in mosquitoes.
Their dimensions are 18-23 µm in diameter, 1.5 mm in length, and filariform.
Wuchereria bancrofti life cycle
Wuchereria bancrofti is digenetic, meaning that it has two hosts throughout its life cycle.
Man is the ultimate host. There is no known animal host or reservoir for W. bancrofti.
The host in between: female mosquitoes from the genera Anopheles, Aedes, and Culex.
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