The document discusses Wucheria bancrofti, the parasitic roundworm that causes lymphatic filariasis. It describes the morphology, life cycle, pathogenesis and clinical manifestations of the parasite. Regarding diagnosis, it explains how microfilaria can be detected microscopically in blood smears, chylous fluid and biopsy specimens. Treatment involves diethylcarbamazine or ivermectin to kill the parasite. Prevention focuses on destroying mosquito breeding sites and using bed nets and repellents.

1. By:
Rajesh B.K
BScMLT 4th Batch
Chitwan Medical College,
Bharatpur-10,Chitwan
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3. AIM
• To know the morphology ,life cycle, pathogenicity and lab diagnosis of
Wucheria bancrofti.
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4. OUTLINE OF PRESENTATION
• Introduction
• Classification
• Wucheria bancrofti
• Morphology
• Mode of Transmission
• Life Cycle
• Pathogenesis
• Signs and Symptoms
• Laboratory Diagnosis
• Epidemiology
• Prevention and control
• Pictures
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5. INTRODUCTION
• Filariasis is the pathological condition caused by infection of Filarial
nematodes transmitted by different vectors.
• Infection occurs in blood vessels, lymphatic system, connective
tissues and serous cavities of man.
• It is the disease of Tropical warm lands.
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6. CLASSIFICATION
• Filariasis is classified depending on the area of the body which the
worms mainly affect. Its classifications include:
1.Lymphatic Filariasis
-affects the lymphatic system.
-can result to a more serious complication such as enlargement of
body parts.
-can cause pain and permanent disability
-caused by Wucheria bancrofti , Brugia malayi , Brugia timori .
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7. 2. Subcutaneous Filariasis
-affects the subcutaneous area of the skin.
-caused by Loa loa , Onchocerca volvulus ,Mansonella streptocerca.
3. Serous Cavity Filariasis
-affects the abdomen’s serous cavity.
-caused by Mansonella ozzardi , Mansonella perstans .
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8. Lymphatic Filariasis
• Three types of worms can cause the disease : Wucheria bancrofti ,
Brugia malayi , Brugia timori
• The worms damage the lymphatic system.
• Wucheria bancrofti is the most common.
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9. Wucheria bancrofti
• It is the most common and widespread species of Filaria infecting humans.
• HABITAT : The adult worm lives in the lymph nodes and lymphatic vessels
of human only. Brancroftian filariasis is not a zoonotic disease since there is
no animal reservoir.
• HISTORY : The larval forms of parasite (microfilaria) were first found by
Demarquay (1863) in hydrocele fluid. The genus is named after Wucherer
who found them in chylous urine in 1868 in Brazil. Lewis (1872) found them
in human blood in Kolkata. Bancroft (1876) found the adult females in
lymphatic abscess ,hence the specific name was given after the discoverer.
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10. • MORPHOLOGY : Adult worms:
-These are long hair-like transparent nematodes (often creamy-white in
color).
-They are filiform in shape and both ends are tapering.
-The Male measures 2.5 to 4 cm in length by 0.1 mm in thickness. Its tail-
end is curved ventrally and contains two spicules of unequal length.
-The Female measures 8-10 cm in length by 0.3 mm in thickness. Its tail-
end is narrow and abruptly pointed. The females are really ovo-viviparous
(laying eggs with well developed embryos).
The life span of the adult worms is about 5 to 10 years.
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12. • Embryos (Microfilaria)
-Passing through lymph nodes, the actively motile embryos find their
way by the main lymphatic trunks into circulatory blood. The embryo
measures about 300 um in length by 6 to 7 um in breadth. When dead
and stained with Romanowsky stains, the embryo shows the following
morphological peculiarities : Hyaline Sheath ,Somatic cells or nuclei
,Granules (nerve ring ,anterior V-spot and posterior V-spot) and Genital
cells (G-cells) .
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13. • Nocturnal periodicity:
The microfilariae of W. bancrofti take rest in the capillaries of lungs
,kidneys, heart and arteries during day time and invade peripheral
circulation at night ,at night from 10 pm to 4am (Nocturnal periodicity).
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15. Life Cycle :-
• Wucheria Bancrofti completes its life cycle in two hosts :
Definitive host = Man
Intermediate host = Female mosquito (mostly Culex , sometimes
Aedes and Anopheles )
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17. • In Intermediate host :
- The sheathed Microfilaria is ingested by mosquito during its blood
meal.
- They cast off their sheath in the stomach within 15-30 minutes ,
penetrate the stomach wall within an hour or two and migrate to
thoracic muscles where they mount and undergo development to 1st
,2nd and then to 3rd stage (filariform) larvae. This actively motile 3rd
stage larva is infective form. Microfilaria does not multiply in mosquito
and only one microfilaria develops into one infective larva only.
-The infective larva is injected into man by mosquito during its blood
meal and the life cycle is repeated.
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18. • In Definitive host :
- When the infected Culex mosquito (most common Culex fatigans )
bites a man ,the filariform larvae are injected into the blood stream.
The larva reaches the lymphatic vessels and lymph nodes along the
blood . They develop into adult worms in 5-18 months in lymphatics
and live there. The adult male fertilize the females which produce
larvae. A new generation of microfilariae is emitted which passes either
through the thoracic duct or the right lymphatic duct ,to the venous
system ,and pulmonary capillaries and then to the peripheral
circulation ,thus completing the cycle.
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19. Pathogenesis and Clinical disease :
A. Lymphatic Filariasis
(a) Early infection : Patients experience fever, lymphangitis, headache,
nausea and urticaria.
(b) Chronic infection: Repeated attacks cause lymphatic damage which
progressively leads to lymphadenitis, lymphedema and other complications.
1. Inflammation : Allergic lymphangitis results from presence of masses of
adult worms in the lymphatics.
2. Dilatation of lymphatics : The presence of adult worms cause
lymphadenitis and duct dilatation ,leading to lymph retention in the areas
drained by the lymph nodes and lymph vessels. Dilatation of lymphatics
leads to lymphangiovarix. Rupture of lymphangiovarix results in:
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20. (a) Lymphorrhagia : Lymph scrotum ,Lymphocele ,Lymphuria.
(b) Chylorrhagia (obstruction in the chyle-bearing vessels ,thoracic
duct) : Chylocele ,Chyluria , Chylous ascites.
(c) Hydrocele : It is a common manifestation of filariasis .Accumulation
of fluid occurs as a result of obstruction of the lymph vessels of the
spermatic cord and also due to exudation from the inflamed testis
and epididymis .Hydrocele fluid is usually clear and straw
colored,occasionally it may be milky ,cloudy or haemorragic.
Occasionally ,the hydrocele assumes enormous proportion in
association with Elephantiasis of Scrotum.
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21. 3. Elephantiasis :It is delayed sequel to repeated and progressive W.
bancrofti infection . It is caused by:
- mechanical blocking of the lumen of lymph vessels ,
- obliterative endolymphangitis due to endothelial proliferation and
inflammatory thickening ,
- excessive fibrosis of lymphatic vessels ,
- fibrosis of afferent lymph nodes draining particular area.
Lymphatic obstruction leads to swelling, fibrosis , and eventually
elephantiasis. The skin surface becomes coarse with warty excrescences.
Elephantiasis most commonly affects limbs, genital organs and breasts.
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22. B. Occult Filariasis :
The term Occult Filariasis refers to a condition which is caused by a
hypersensitivity reaction to microfilarial antigens and is characterized
by massive eosinophilia (30-80%) ,hepatosplenomegaly and absence of
Microfilaraemia.
Adult female produces microfilaria in lymph node but they do
not reach peripheral blood as they are destroyed in the tissues.
Tropical Pulmonary Eosinophilia (TPE) : This is a manifestation of
occult filariasis and is characterized by low fever ,loss of weight ,
paroxysmal cough with scanty sputum(may be blood-tinged) and
splenomegaly.
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23. Laboratory diagnosis:
• Specimens :- Blood , Chylous urine ,Hydrocele fluid and Biopsied lymph node.
1. MICROSCOPY: Definitive diagnosis is made by detection of microfilariae in a
thick blood smear and chylous fluid.
(a) Examination of Blood
1. Thick blood smear technique:
-Smear made from two drops of deposit is stained by Leishman/Giemsa
stain and examined microscopically.
2. Wet-slide preparation :
-Two drops of deposit is mixed with equal volume of water (to lyse the red
cells) on a slide. The preparation is covered with a coverslip and examined
microscopically using low power (10x).
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24. 3/6/2017 24Fig: Giemsa Stain of Microfilariae

25. (b) Examination of Chylous fluid
- Chylous fluid is creamy white and opalescent . Chyle consists of
lymph and particles of digested fat (ether soluble).
Procedure:- Urine is centrifuged at 2000 rpm for 10-15 minutes. The
supernatant is thrown out and the deposit is mixed with equal volume
of water and centrifuged again. The supernatant is discarded and wet
preparation from deposit is placed on slide, covered by coverslip,
examined for the presence of microfilariae. The deposit may be
smeared on slide and stained by Leishman or Giemsa stain.
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26. (c) Examination of Biopsy specimens :
-Adults filarial worms can sometimes be found in sections of biopsied
lymph nodes as incidental findings.
-This is not done for routine diagnosis.
2. Serological tests like ELISA test and IHA test can be used for detection of
antibodies to larval antigens.
3. PCR assay for the detection of microfilariae infection of W. Bancrofti has
been developed.
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27. 4. X-Ray examination shows calcified adult worm. USG can detect adult
W. bancrofti in lymphatic vessels of scrotum in infected male and of
breast in infected female.
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28. TREATMENT
• Diethylcarbamazine (DEC) is the drug of choice ,because it is effective
against both adults and microfilariae.
• Ivermectin destroys microfilariae ,but not adults.
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29. PREVENTION
• Destruction of breeding sites of vectors.
• Using bed nets while sleeping.
• Applying repellant creams on skin.
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30. PICTURES
3/6/2017 30Source : Epidemiology disease control Nepal

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36. Conclusion:
• W. brancrofti causes bancroftian filariasis ,elephantiasis.
• It is the most common and widespread species of filarial infecting
humans.
• Completes its life cycle in two host :Man and Female mosquito.
• 3rd stage larva is infective form.
• Lab diagnosis includes:
-Detection of microfilaria in blood, urine and hydrocele fluid.
-Demonstration of adult worm in biopsy specimen.
-Immunudiagnosis: detection of antigen and antibody.
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37. References:
• Textbook of Medical Parasitology ,P. Chakraborty.
• Parasitology 13th edition ,K.D. Chatterjee.
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