Filariae species & Lymphatic filariasis.pptx

Blood and
Tissue
Nematodes
Prof. Dr/ Ibrahim Aboul Asaad
Lecture for PG
Subsidiary Parasitology

• Filariae are parasitic worms belonging to the family Filariidae and are
responsible for a group of diseases known as filariasis. These thread-like
nematodes typically inhabit the lymphatic system, subcutaneous tissues, or
body cavities of their hosts, which include humans and other animals. The
main species affecting humans are classified according to the habitat into:
Introduction
1) Lymphatic Group: *Wuchereria bancrofti, endemic in Africa & Egypt
*Brugia malayi, endemic in Fare east
2) Cutaneous Group: *Onchocerca volvulus, , endemic in Africa
*Loa loa, endemic in Africa
3) Serous Group: *Mansonella ozzardi, endemic in Central and South America
*Mansonella perstans, endemic in Africa
• Filariasis is a significant public health problem in tropical and subtropical
regions, affecting millions of people worldwide. Efforts by global health
organizations aim to eliminate filariasis through widespread treatment and
preventive measures.
Filariae

1) Adults: Pathogenic Stage
2) Microfilaria (pre-larvae or embryos):Diagnostic Stage
3) Larval stages: 5 larval stages
1.Slender, creamy white & range from 2 to 50 cm in length.
2.The male has curved posterior end with two copulatory
spicules.
3.The female:
o The female is viviparous and gives birth to microfilariae.
o Has two sets of genitalia;
o The vulva opens close to the anterior end.
The adults:
Morphology of Filariae
The parasite stages
Filariae

Microfilariae are the diagnostic stages ,,,,, why??
1) Microfilariae are released in blood, so can be detected in blood
samples
2) Each species of microfilaria has characteristic morphology and
periodicity,
Microfilariae:
Microfilariae are "pre-larvae or advanced embryos" which will develop into
(L1) in the arthropod vector.
Larval stages:
L1  L2  L3  L4  L5
Infective
Stage
Rhabditiform L
In arthropde I.H
Immature adult
In D.H
Filariae

Species Habitat D. H. I.H. (Vector)
W. bancrofti Lymphatics Human only Culex, Aedes & Anopheles.
B. malayi Lymphatics Human & R.H
(monkey, cats)
Anopheles, Mansonia
L. loa Skin Human only Chrysops (Deerfly)
O. volvulus Skin Human only Simulium (black fly)
M. perstans Body cavities Human only Culicoides spp.
M. ozzardi Body cavities Human only Culicoides spp.
Life cycle Filariae
Habitats and Hosts:
Infective stage: Filariform larva (L3)
Route of infection: Skin penetration through the insect bite
Diagnostic Stage: Microfilariae
Filariae

Transmission and Life Cycle:
• Filariae are transmitted to humans through the bites of
infected mosquitoes (for lymphatic filariasis) or blackflies (for
onchocerciasis). The life cycle of filariae involves several stages:
1. Infection Stage: Larvae (L3) enter the host's body
through insect bites.
2. Migration and Maturation: The larvae migrate to
specific tissues (lymphatic system, subcutaneous
tissues or serous cavities) where they mature into
adult worms.
3. Reproduction: Adult worms reproduce, releasing
new microfilariae into the host's bloodstream or
skin, which can be ingested by biting insects,
continuing the cycle.
Filariae

Lymphatic
Filariasis
• Wuchereria bancrofti
• Brugia malayi
• Brugia timori

1) Habitat:
2) Hosts:
4) Diagnostic stage:
5) Route of infection:
3) Infective stage:
6) Life span:
Adult: Lymphatics
Microfilariae: Blood (night)
I.H. (Vector)
Culex, Aedes Anopheles: W. bancrofti
Anopheles, Mansonia: B. malayi
D.H.: Human
R.H.: monkey, cats for : B. malayi
Filariform larva (L3)
Skin penetration through the insect bite
The microfilariae in blood
Adult: 5 – 10 years & microfilaria: 5-20 months
Life Cycle of lymphatic Filariae

Adults in
lymphatics
Microfilariae metamorphose
to L1  2 molts  L3
MF penetrate stomach
to thoracic muscle
Infective (L3) enter
through mosquito bite
MF appear in
peripheral blood
at night
Mosquito ingests
MF with blood
L3 molt twice & adults
appear in lymphatics
after 6-12 Ms
L3 migrate to proboscis &
drop on skin during biting
Mosquito
I.H.
Mosquito
I.H.
Human
D.H.
Life Cycle of lymphatic Filariae

Lymphatic Filariasis:
ELEPHANTIASIS
• Clinical aspects .
• Diagnosis.
• Treatment.
• Prevention & control of infection.

• Filarial pathogenesis is caused mainly by adult worms
• Microfilariae do not cause pathological manifestations although they
have been associated with granulomatous inflammation of the lung, liver,
and spleen
The infection could be classified into:
1) Asymptomatic: Microfilaraemia without manifestations referable to their
infection.
2) Acute inflammatory filariasis.
3) Chronic obstructive filariasis.
4) Occult filariasis.

Caused by immunologic reaction to the toxic products of the adult worms.
The manifestations occur in irregular attacks for months or years, and include:
Causes of Lymphangitis and Lymphangitis
1) Mechanical irritation
2) Liberation of metabolites of growing larvae & secretion of some toxic fluid by
fertilized females
3) Absorption of toxic products liberated from dead worms undergoing
disintegration.
4) Secondary bacterial infection

Lymphatic
inflammations &
Lymphatic
oedema

Acute inflammation of the testis and epididymis 
 pain,
 scrotal swelling and redness,
 fever
Recurrent attacks of orchitis  Collection of serous fluid
in the cavity of the tunica vaginalis (Hydrocoele)
o Develops within superficial lymphatics
on the limbs or scrotum.
o Rupture with ulcer formation and
discharge of pus.
o Pus may be sterile or septic.

Chronic Obstructive Filariasis
Elephantiasis
It develops slowly after years of filarial infection.
It is preceded by repeated acute inflammatory attacks & chronic oedema
Pathogeneses of Lymphatic obstruction:
1) Fibrosis following the repeated acute inflammatory attacks.
2) The coiled worms or the proliferative granulation tissue after its death.
Lymphatic obstruction leads to:
1) Chronic lymphatic oedema
2) Chyluria & Chylocele
3) Elephantiasis
1. Chronic lymphatic oedema
 Frequently affects the legs and external genitalia or the arms and breasts
 Non-pitting and irreversible with limb elevation.

2. Chyluria & Chylocele
 Lymphatic obstruction  lymph varices  Rupture in the cavity of the
Tunica vaginalis  Chylocele.
 Or rupture in the urinary bladder  Lymph passes with urine  Milky
urine (Chyluria)
3. Elephantiasis
Pathogenesis: Chronic lymphatic oedema leads to:
• Proliferation of the dermal and connective tissue of the skin due to the high protein
content of the lymph.
• Gradually, over a period of years, the affected limb becomes thickened, rough and
fissured.

Elephantiasis
a) Lower limb
b) Upper limb
c) Scrotum
d) Breast

4. Occult Filariasis
Filarial infections in which microfilariae are not found in the peripheral blood although they
may be seen in tissues.
Cause: Hypersensitivity reaction to filarial antigens derived from the microfilariae
Clinical manifestations
 Tropical pulmonary eosinophilia (TPE)
• Severe Cough and wheezing.
• Peripheral blood eosinophilia.
• Extreme elevation of anti-filarial antibodies (especially IgE).
 Glomerulonephritis.
 Myocardial fibrosis.
 Filarial arthritis.
 Filarial fever.
Diagnosis of Occult Filariasis:
1) Peripheral blood eosinophilia.
2) Extreme elevation of immunoglobins (especially IgE).
3) Extreme elevation of anti-filarial antibodies.
4) Finding a circulating filarial antigen in the blood.

• Clinical diagnosis: The presence of the characteristic signs and symptoms
in persons in endemic regions.
• Laboratory diagnosis
o Direct laboratory diagnosis
o Indirect (Serological) diagnosis
o PCR
• Imaging techniques.
Diagnosis of lymphatic Filariasis

2) Laboratory diagnosis
a) Direct laboratory diagnosis
1) demonstration of adults in lymph node biopsy
2) demonstration of microfilariae in:
a) Blood sample
b) Urine sediment, when chyluria present
c) Lymph node aspirate or biopsy
Blood sample:
• The proper blood samples can be obtained at night or after provocation test.
• DEC provocation test: Oral administration of 100 mg of (DEC) usually provokes
movement of the microfilariae to the peripheral blood, within 30 - 45 minutes in
daytime
Examination of blood samples can be performed by:
1) Thin or thick blood films stained with Wright’s or Giemsa stain.
2) concentration method:
a) Knott's concentration method.
b) Membrane filtration concentration method.

Length 260 µm
Length 220 µm
Tail free
of nuclei
Tail contains nuclei
Nocturnal Periodicity
Loose Sheath
Microfilariae
Sheath
Sheath
Microfilariae in blood film

Adult sections in lymph node biopsy

Microfilaria in Urine Sediment

Microfilariae cannot be detected in blood of the infected patient (False Negative ) in
cases of:
1) During the early months of infection.
2) Chronic stages of elephantiasis  the adult worms and microfilariae may
have died.
3) In occult filariasis.
In these situations, serological tests for detection of circulating filarial antigens or
antibodies appear to be the diagnostic method of choice.
b) Indirect (serological) diagnosis
A polymerase chain reaction (PCR) assay based on detection of DNA sequence found in
Filariae is useful in amicrofilaraemic cases.
It is significantly more sensitive than current methods for diagnosing filariasis, and it
overcomes many difficulties in identifying active infection.
c) Polymerase Chain Reaction (PCR)

3) Imaging techniques
o X-ray can show calcified died adult worm in lymphatics
o US, CT, or MRI may reveal living adult worms
Ultrasound
Filarial dance sign
The constant movements of the worms in Chylus fluid during ultrasonography.

Medio-lateral oblique (MLO) view of a
digital mammogram of the left female
breast showing multiple coiled and
serpiginous calcifications which are
characteristic of calcified filarial worms
within the breast parenchyma
X-ray

Treatment
i. General measures: Rest, antibiotics, antihistaminic and bandaging
ii. Ant-filarial drugs:
DEC or hetrazan:
Oral dose of 2mg/kg tds for 12 days.
 It is very effective in killing the microfilariae.
 It is less effective in killing the adult worms
Ivermectin
It is effective in killing microfilariae, but not the adult.
It has the advantage of being given in a single oral dose (200 µg/kg).
Albendazole
 A course of 400mg twice daily for 3-week.
 Effective in killing the adults

iii. Surgical procedure:
Plastic surgery for more advanced elephantiasis.
Combined Therapy
Albendazole combined with Ivermectin or (DEC) in a single dose is also
effective treatment for killing adult filarial worms
Doxycycline antibiotic
Filarial parasites have symbiotic bacteria, which live inside the worm.
When these bacteria are killed, the worms themselves also die.
This can be obtained by 8-week treatment with doxycycline

Prevention and control
• Prevention and control strategies include vector control measures like
insecticide-treated nets, indoor residual spraying, and larviciding, as well as
personal protective measures such as repellents and protective clothing.
• Mass drug administration (MDA) of antiparasitic medications is crucial for
reducing microfilariae levels and halting transmission.
• Additionally, morbidity management and disability prevention (MMDP) focus
on lymphedema management and hydrocele surgery.
• Global efforts, led by the World Health Organization (WHO) and supported by
various partnerships, aim to eliminate LF through coordinated interventions,
community engagement, and ongoing surveillance.

Thank You
Prof. Dr/ IbrahimAboulAsaad

Filariae species & Lymphatic filariasis.pptx

More Related Content

What's hot

Similar to Filariae species & Lymphatic filariasis.pptx

Recently uploaded

Filariae species & Lymphatic filariasis.pptx