This document summarizes information about lymphatic filariasis, which is caused by infection with nematodes Wuchereria bancrofti and Brugia malayi. It affects over 120 million people globally. The life cycle involves transmission between humans and mosquitoes. Adult worms reside in human lymphatic vessels and nodes, producing microfilariae that circulate in blood mostly at night. This can lead to lymphadenitis, lymphangitis, lymphedema, and elephantiasis over time. Diagnosis involves detecting microfilariae or using immunological and molecular tests. Treatment is diethylcarbamazine to kill microfilariae and mosquito control to block transmission.

1. Dr. Neelam Gupta, MD

2.  Arthropod borne Tissue dwelling parasites
 arthropods as intermediate hosts
 Many affect domestic animals or humans:
 Lymphatic filariasis: Wuchereria bancrofti
Brugia spp,
 River Blindness: Onchocerca volvulus

3.  Life cycle is passed in two hosts.
 Humans are the definitive host
 Transmitted by
 Culex, Aedes, and Anopheles species.

4.  Lymphatic filariasis is caused by infection with
nematodes of the family Filarioidea: most of the
infections are caused byWuchereria bancrofti
and most of the remainder by Brugia malayi.
 Humans are the exclusive host of infection
with W. bancrofti. Although certain strains of B.
malayi can also infect some animal species
(felines and monkeys)


5.  Endemic in 83 countries
 1.2 billion at risk
 More than 120 million people infected
 More than 25 million men suffer from
genital symptoms
 More than 15 million people suffer from
lymphoedema or elephantiasis of the leg

6.  Habitat : adult male and feamale worm reside
in lynph nodes and lymphatics of man.
 Microfilaria are found in blood.

7.  Adult worm are long hair like transparent,
creamy white,long, hair like nematodes,
filariform in shape with tapering ends.
 Male measures 2.5 to 4 cm in length by 0.1
mm in thickness and female measures 8 to
10 cm in length and 0.3 mm in thickness.
 Tail end of male worm is curved ventrally with
two spicules of unequal length, while that of
female worm is narrow and abruptly pointed.

8.  The female are viviparous and liberates
sheathed embryos, the microfilariae into
lymph .

9. female
male

10.  Transparent and colourless with blunt head
and pointed tail .
 Covered by hyaline sheath which is longer
than larva. It can move forwards and
backwards in sheath.
 Nuclei appear as granules in the central axis
of microfilaria.
 Tail tip is free from nuclei.

11.  Found in peripheral blood and often in the
hydrocele fluid and chylous urine.

13. A, Wuchereria bancrofti. B, Brugia malayi.
C, Loaloa.
D, Onchocerca volvulus. E, Mansonella
perstans. F, Mansonella
streptocerca. G, Mansonella ozzardi

15.  There is a marked periodicity in the circulation
of microfilaria in the blood.
 They will be present in high numbers in the
peripheral blood during mid night between
10p to 2am and scanty or absent at day time.
This type of periodicity is called as nocturnal
periodicity.
 Body temperature, oxygen,sleeping habits etc
may influence the periodic pattern of the
microfilaria.

16.  Completes life cycle in two hosts.
 Definitive host: Man.
 Intermediate host: Mosquitoes:
 Culex quinquefaciatus (50%)
 Anopheles (rural areas)
 Aedes Species.

17. sheathed microfilariae ingested. After
2-6 hrs penetrate stomach wall to
reach thoracic muscles.
On 10-
11th day
3rd stage
infective
larva is
fully
formed
Mosquito injects 3rd stage larva in
man through skin which enter into
lymphatics &settle in L.N
In 1 yr they
are sexually
mature.
After
fertilization
female
produces
microfilariae

19.  The infections are mainly classified into two
forms
 1.BANCROFTIAN FILARIASIS.
 2.OCCULT FILARIASIS.
 3. TROPICAL PULMONARY EOSINOPHILIA

20.  The pathogenic effect is produced by adult
worms of Wuchereria.
 LYMPH NODES BECOME ENLARGED FIRM
AND FIBROTIC.
 m/s- lymph nodes show lymphocytes, plasma
cells, polymorphs and eosinophils.
 Adult worms can be seen in lumen of
lymphatic vessels.
 In chronic disease dead worms with fibrotic
and calcified tissue is seen.

21.  Lymphangitis with swelling. Redness and pain .
 Mechanical irritation
 Liberation of metabolites
 Absorption of toxic products.
 Secondary bacterial infections.
 chronic inflammation leads to damaged and
incompetent lymph valves.
 Increased pemeability of wall of lymphatics.

22.  Lymphatic obstruction- due to dead
worms, obliterative endolymphangitis,
exessive fibrosis of lymphatic vessels and
afferent lymph nodes.

23.  Repeated leakage of lymph in tissues lead to
lymphoedema and swelling of the limbs,
breasts and genitalia.
 Non-pitting edema and verrucous growth
occurs with secondary bacterial and fungal
infection.
 in males, hydrocele, orchitis, epidydimitis are
common.
 Chyluria – lymph getting in urine can occur .
 Lymphangiovarices occur in inguinal,
scrotal, testicular, abdominal sites

25. Bouts of fever, headache, malaise,pain
and lymphangitis and lymphadenitis of
axilla or groin region are common during
incubation period. Blood examination may
show high eosinophilia.

26.  Occult filariasis is believed to be the result of
hyper responsiveness to filarial antigens
derived from mf.
 Massive eosinophilia , generalised L.N.
enlargement, helatospenomegaly and
pulmonary symptoms.
 Eosinophilic granulomas develop.

27. Malaise, fever , wt loss and respiratory
symptoms- dry nocturnal cough, dyspnoea
and wheezing, with marked increase in
eosinophil count.
X-ray shows diffused miliary mottling and and
increased broncoalveolar markings.
Total serum IgE is increased and antibodies to
filaria of high titre.
Associated with W. bancrofti and Brugia malayi
infections.

28.  Detection of microfilariae.
 Detection of adult worm.
 Immunodiagnosis.
 DNA probes.

29.  Filariasis is usually diagnosed by identifying
microfilariae on Giemsa stained, thin and thick
strict windows of the time of day must be observed.
 Membrane fitration , centrifugation and
sedimentation tecniques used for suboptimal times.
 Anticoagulated blood mounts can be seen for
microfilaria.
 Acridine orange –microhaematocrit tecnique can be
used.
 The DEC(diethylcarbamazine)
(2mg/kg)provocation test is performed to obtain
satisfying numbers of parasites in daytime samples

30.  Lymph node aspirate and chylus fluid
may also yield microfilariae.
 Detection of adult worm – in biopsied L.N
X-ray can show calcified adult worms.
 Antibody tests —Serologic tests for filarial
antibodies which detect elevated levels of
IgGand IgEare available

31. Polymerase chain reaction (PCR) , DNA probes
and antigenic assays, which detect circulating
filarial antigens, are also available for making
the diagnosis.

32.  DEC Diethyl Carbomazine citrate (DEC)
 Dose: 6mg/Kg/12 days

33.  Mosquito control:
 Physical:Mosquito net,
 Effective drainage system.
 Chemical :Mosquito repellents,DDT
 Biological:Gambusiya fish.

34.  Habitat- L.N and lymphatic vessels. And
microfilaria in blood of man.
 Morphology – resembles W. bancrofti, though
smaller in size.
 Sheathed larva like wuchreria.
 Secondary kinks present, cephalic space is
longer.
 Nuclear column appears blurred in giemsa
staining.
 2 discrete nuclie at tip of tail.
 Show nocturnal periodicity.

36.  Life cycle is similar but I.H are Mansonia,
anopheles and aedes.
 Pathogenicity- similar to bancroftian filariasis
but elephantiasis is restricted to legs and no
chyluria or involvement of male genetalia.
 Can cause TPE
 Lab diagnosis- demonstration of microfilaria.
And adult worms.

37. Brugia malayi
The adult females of B malayi
resembles to W. bancrofti
Brugia timori
Similar to B. malayi .

38.  Brugia timori microfilaria differ by failure of
the sheath to stain with giemsa and long
cephalic space. Greater no of nuclie in tail (5-
8)
 Lesions are few and mild.
 Lymphangitis , lymphadenitis and
elephantiasis below the knee.
 Lab dia and tratment similar to B. MALAYI
INFECTION.