BANCROFT’S

FILARIASIS

SUBMITTED TO

DEPARTMENT OF ZOOLOGY

ISABELLA THOBURN COLLEGE

LUCKNOW

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.

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)

Morphology

Adult worm

Third stage

larva

Microfilariae

(first stage larva)

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

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 periodicityPresent in high number in

peripheral blood at

midnight

Eg- Brugia malayi

Diurnal periodicityPresent in greatest number

in peripheral blood during

day time

Eg- Loa loa

MORPHOLOGY OF MICROFILARIAE

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

LIFE CYCLE

• DEFINITIVE HOST- Man

(In human lymphatic system)

• INTERMEDIATE HOST-

Mosquitoes

Culex quinquesfasciatus

Anopheles

Aedes

Culex

quinquesfasciatus

Aedes

Anopheles

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)

CLINICAL MENIFESTATION

LYMPHATIC

FILARIASIS

OCCULT

FILARIASIS

endemic normal

Asymptomatic stage

Acute filariasis

Chronic filariasis

Non-filarial

elephantiasis

Tropical pulmonary

eosinophilia

(TPE)

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

ELEPHANTIASIS

THANK YOU…

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

variceschyluria

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

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

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 testa. 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)

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)

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