( wuchereria bancrofti) FILARIASIS FOR M.Sc students

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