Wuchereria bancrofti is a parasitic nematode that causes lymphatic filariasis (elephantiasis) in humans. It is transmitted by mosquitoes and lives in the human lymphatic system. The parasite has a complex life cycle involving microfilariae in human blood that are ingested by mosquitoes during feeding. The mosquito serves as an intermediate host where the microfilariae develop into infective larvae, which are then transmitted to humans during subsequent blood feeding, developing into adult worms in the lymphatics. Clinical manifestations range from asymptomatic microfilaremia to lymphedema and elephantiasis of the legs and genitals due to long-term infection and damage.

1. BANCROFT’S
FILARIASIS
SUBMITTED TO
DEPARTMENT OF ZOOLOGY
ISABELLA THOBURN COLLEGE
LUCKNOW

2. INTRODUCTION
 Filariasis is the term for a group of disease caused by
parasitic nematodes.
 Filariasis caused by nematodes that live in the human
lymph system, Bancroftian filariasis or Lymphatic
filariasis.
 Causative organism- filarial worm Wuchereria bancrofti
(Cobbold 1877)
 Elephantiasis is the end result of disease.
• Cutaneous and subcutaneous tissue enlarge and harden in
areas where lymph has accumulated.
• Usually occurs in lower extremities.

3. Wuchereria bancrofti
 Common name- Bancroft’s filaria
Bancroft (1876-77) demonstrated adult female and
Sibthorpe (1888) first found adult male.
Manson (1878) first demonstrated the culex mosquitoes
as the INTERMEDIATE HOST.
Geographical distribution
• Very widespread and
important human parasite in
worm countries.
• In Africa (Mediterranean and
east west coastal areas)
• In Asia (coasts of Arabia,
India, Malaya and north to
china.
Habitat
• Filarial worm inhabit the
lymphatic vessels, especially
the lymph nodes of man and
other vertebrates.
• Microfilariae are found in
peripheral blood (also found
in chylous urine or
hydrocele fluid)

4. Morphology
Adult worm
Third stage
larva
Microfilariae
(first stage larva)

5. ADULT WORM
 Long hair like transparent nematodes
 Creamy white in colour.
 Filiform in shape, both ends are tapering
 Male- 2.5-4 cm in length and 0.1mm thickness
 Tail end is curved ventrally contain 2 spicules
 Female- 8-10cm in length and 0.2-0.3mm
thickness
 Tail end is narrow and abruptly pointed
 Ovo-viviparous, though liberating active
embryos.
 Male and female coiled together, can be
separated with difficulty
 Life span is long, 5-10 years Wuchereria bancrofti

6. MICROFILARIAE
 First stage larva
 Location- peripheral blood and often in
hydrocele fluid and chylous urine
 Size- 244-296 micrometre in length and
7.5-10micrometre in diameter
 Body- transparent and colourless,
covered by hyaline sheath
 They can live up to 70 days in human
blood
 Microfilarial periodicity-
Nocturnal periodicity
Present in high number in
peripheral blood at
midnight
Eg- Brugia malayi
Diurnal periodicity
Present in greatest number
in peripheral blood during
day time
Eg- Loa loa
MORPHOLOGY OF MICROFILARIAE

7. THIRD STAGE LARVA
 Infective form of the filarial worm in human.
 Shape- elongated, Filiform
 Size- 1.4-2 micrometre in length and 18-23
micrometre in breadth
MICROFILARIAE IN
BLOOD FILM

8. LIFE CYCLE
• DEFINITIVE HOST- Man
(In human lymphatic system)
• INTERMEDIATE HOST-
Mosquitoes
 Culex quinquesfasciatus
 Anopheles
 Aedes
Culex
quinquesfasciatus
Aedes
Anopheles

10. PATHOGENICITY
 INFECTION- Wuchereriasis (commonly called
filariasis)
 MODE OF INFECTION- Inoculative method,
through the bite of mosquito
 TRANSMITTING AGENT- Female mosquito(Culex,
Aedes, Anopheles)
 INFECTIVE FORM-Third stage larva
 PORTAL OF ENTRY-Skin
 SITE OF LOCALIZATION-Lymphatic system of
superior or inferior extremities
 INCUBATION PERIOD- About 1 to 2 years(3rd stage
infective larva grows to adult form)

11. CLINICAL MENIFESTATION
LYMPHATIC
FILARIASIS
OCCULT
FILARIASIS
 endemic normal
 Asymptomatic stage
 Acute filariasis
 Chronic filariasis
 Non-filarial
elephantiasis
 Tropical pulmonary
eosinophilia
(TPE)

12. LYMPHATIC FILARIASIS
ENDEMIC NORMAL
• In the area of
endemic filariasis, a
certain proportion of
the population living
in these area do not
show any overt
clinical manifestation
of disease
• Difficult to know,
people are infected or
not
ASYMPTOMATIC
STAGE
• Have microfilariae
in their blood but
do not show any
symptoms of
disease
• Remains
asymptomatic for
years or even life
ACUTE
FILARIASIS
• Filarial fever and
lymphadenitis
(major symptoms)
• May occur several
times a year

13. ELEPHANTIASIS

14. THANK YOU…

15. 1. Hydrocele- obstruction of
the lymph vessels of
spermatic cord and
inflammation in testes
2. Elephantiasis- affected part
become enormously enlarged
(tumour like solidity)
• The surface of skin become
rough and papliomatous
• Hairs become rough and
sparse
CHRONIC
FILARIASIS
Hydrocele elephantiasis
1. Lymph varices-
varicosity of lymphatic
vessels (abdominal and
genital area)
2. Chyluria- escape of chyle
through the urine (rapture
of varicose chyle vessels)
• Microfilariae are detected
in chylous urine and
peripheral blood
NON- FILARIAL
ELEPHANTIASIS
Lymph
varices
chyluria

16. OCCULT FILARIASIS
• Hypersensitivity reaction of the host to
Microfilarial antigen
• Microfilariae are not detected in peripheral blood
• Examples- tropical pulmonary eosinophilia
(TPE), Less frequently arthritis
TROPICAL PULMONARY EOSINOPHILIA (TPE)
Eosinophilic lung, Weingarten’s syndrome
• Characterised by low fever, loss of weight, paroxysmal
cough with scanty sputum, dyspnoea and splenomegaly
• Chest radiography shows increased branchiovascular
marking or military “mottling” in lung fields
• Microfilariae may b e demonstrated in tissue obtained by
lung biopsy

17. EPIDEMIOLOGY
 GEOGRAPHICAL DISTRIBUTION- topics and
subtropics of Asia, Africa, South America
• Periodic nocturnal W. bancrofti is the most
widespread
• Endemic in India, China and other countries of
South-East Asia
 RESERVOIR HOST AND TRANSMISSION OF
INFECTION
• Infected person with circulating microfilariae are the
chief source of reservoir and infection
• Man- to- man transmission by the bite of mosquito

18. DIAGNOSIS
 DIRECT EVIDENCES
1. Microfilariae (sheathed having
tail- tip free from nucleus)
• In peripheral blood
• In chylous urine
• In hydrocele fluid
2. Adult worm
• In biopsied lymph nodes
• Calcified worm by X-ray
 INDIRECT EVIDENCES
1. Allergic test
a. Blood examination(eosinophilia 5 to
15%)
b. Intradermat test- an immediate
hypersensitivity reaction
2. Immunological test
(complement fixative test)
• A sensitive test for loiasis and occult
filariasis
Other tests-
• Biopsy (for purely diagnostic purpose)
• Serological diagnosis (ELISA, RIA)
• Trop Bio Test (detection of adult worm infection not depends on
Microfilarial periodicity)
• PCR assay (detection of Microfilarial infection)
• X-ray examination ( shows calcified adult worm)

19. TREATMENT
Diethyl carbamazine (DEC)
• Kills mainly microfilariae
• Most effective against 3rd and 4th stage larva
• Adenolymphangitis decreases significantly
• Cheap, effective and safe with few side effects
(fever, chill, headache etc.)
DOSE
1st day - 50mg after food
2nd day - 50mg three times daily
3rd day - 100mg three times daily
4th day – 21st day - 5mg/kg/day in three
divided dose
Other drugs
• Iveemeciin (150ug/kg body wt., destroy microfilariae, no
mocrofilaricidal effect)
• Lavamisole
• Mebendazole
• Centprazine (CDRI Lucknow)

20. PREVENTION AND CONTROL
1. Mosquito control
• clinical control by spraying
insecticides (DDT, malathion)
• Biological control by the use of
carnivorous bacteria(Bacillus
sphaericus), carnivorous fishes
(Poecilia reticulata)
• Environmental control by efficient
drainage and sewage system
2. Chemotherapeutic control
• Reduce morbidity du to filariasis by
treating clinical case
• Lower transmission by treating the
case of crofilaraemia
• Interrupt transmission of the
infection
• Based on mass or selective treatment
of the cases by administering DEC