wuchereria bancrofti can causes serious diseases that attack our world . so this presentation gives us some information about this worm , methods of avoiding it and what are diagnostic tests that doctors ask .

1. WUCHERERIA
BANCROFTI
BY:
Norhan Ahmed
Faculty of Medicine
EGYPT

2. Geographical distribution
Africa ,Asia &partsof southAmerica In Egypt
; cases are detectedin kalyobia, Dakahilia
,Sharkia,Cairo ,Giza&Assuit

3. Life Cycle
The adults live in the lymphatics of man (no
reservoir host) .
Microfilariae laid by the female reach the
blood by migration through the wall of the
lymphatics to the neighboring small blood
vessels .
Microfilariae gradually appear in the
peripheral blood by night (nocturnal
periodicity ) reaching maximum about
midnight (10am – 2am),and gradually
disappear by day time .

4. The microfilaria are ingested by the
mosquito intermediate host with its
blood meal . Species of the genera
CULEX , AEDES & Anopheles act as
vectors .In Egypt it is CULEX PIPIENS .
In the mosquito’s stomach , the
microfilaria loses its sheath , penetrates
the gut wall and invades the thoracic
muscles within 24 hours .
There it settles & moults assuming a
short sausage shaped larvae (200×15 u).

5. After a few days it moults again (300×20 u).
About the tenth day the larvae becomes
long & slender (2000×20 u ) . The filaform
larvae ( the infective stage ) migrates from
the thorax to the head , reaches the
proboscis & enters the labium .
When the mosquito bites man , the
infective larvae attracted by warmth of the
skin , pierce the labium & penetrate the
skin or enter the bite wound .

6. Larvae pass to the lymphatics vessels & nodes where
they grow to maturity in 6 to 12 months . They live &
produce microfilaria for 5 to 10 years . Microfilaria live
for 2 years .

7. FILARIA PEROIDICITY
Causes unknown , theories that explain
periodicity are :
• Biological theory : inborn periodicity related
to the habit of the insect vector biting
activity , mosquitoes are night biters .
• Chemical theory : positive chemotaxis
between the microfilaria & saliva of the
mosquito .

8. • PH of the blood theory : decreased
oxygen content & increased carbon
dioxide content while sleeping may
stimulate the microfilaria to migrate to the
peripheral circulation . By day time the
reverse occurs.
• Lymphatic blockage theory : as adult
worms are mainly found in the lower limbs
& during day the patient attains an upright
position the born microfilaria go to the
circulation during sleeping .

9. Pathogenesis & clinical picture
Asymptomatic
In endemic areas where children are exposed to
infection at an early age . Many adults exhibit
microfilariae in their blood without symptoms
referable to their infection .
On physical examination , the patient may
exhibit a moderate generalized enlargement of
lymph nodes especially of inguinal region .
Blood examination shows numerous microfilaria
& a low grade eosinophilia .

10. Acute inflammatory phase
Due to toxic products of worms &
immunological reaction to it . Incubation
period ( about one year after the infective
bite ) then the following symptoms appear .
Filaria or elephantoid fever :recurrent attacks of
fever with rigors ends with sweating ( lasts
few hours to several days)

11. Recurrent attacks of lymphatics & lymphadenitis mainly
of the legs & genitallia .
The legs show: raised , red , hot , swollen &
tender streaks. Bacterial & fungal super-
infection .
The genitallia shows:
Funiculitis : Inflammation of the
spermatic cord

12. Orchitis : Inflammation of the testis .
Epididymitis : Inflammation of the
epididymis
Epididymis- orchitis : Inflammation of
the epididymis & testis .
Chronic obstructive phase
• Distension & varicosities of lymph vessels
distally . Fibrous tissue is deposited around
lymph vessel .

13. • Persistent lymphatic
edema .
• Lymph flow is
obstructed .
• Elephantiasis &
hydrocele .
• Rupture of distended
lymphatics leads to
release of chyluria ,
chylocele , chylothorax
& chylous diarrhea .

14. Diagnosis
Clinical History
Presence of history of exposure to mosquito
in an endemic area , together with clinical
finding .
Laboratory investigations
1- Blood examination for microfilaria
2- Polycarbonate filters ( Nucleopre)
technique : the microfilaria are trapped on
the filter after the RBCs have been lysed by
3% acetic acid .

15. The 3 sum pore size filters
may be examined directly
on a microscope slide
because they are
transparent when wet.
3-Knott’s concentration
technique : add 2 ml
blood to 10 ml 2% formalin
, leave for 10 min then
centrifuge & examine
sediment either as a direct
wet film or after staining
with methylene blue .

16. 4 – Hetrazan provocation
test : microfilaria may be
demonstrated in blood at
daytime by administration of
100 ml of diethylcarbamazine
orally , 45 to 60 min before the
blood specimen is taken .
5 – Serological test :
detection of antibodies to
filarial antigen may be of
diagnostic value when malaria
can’t be found .
6 – Intradermal test : skin
test using antigen from dog
heartworm , DIROFILARIA
IMMITIS , is group – specific for
filarial infections .

17. Detection of adults in lymph node biopsy
Imaging techniques :
Lymphoscintography : shows lymphatic
dilatation . Soluble or fine colloidal
material is injected interstitially .
They will be taken up into the lymphatics
vessels then into the draining lymph node.
Ultrasonography : shows adults in
lymphatics ( when viable they give filarial
dance sign )

18. ultrasonography

19. Treatment
1 – Diethylcarbamzine ( DEC, Hetrazan) : the
drug is effective in killing microfilaria ( rapidly)
adults worms (slowly) , can be given orally in
dosage 2 mg/kg for 12 days .
2 – Ivermectin : taken as single oral dose 200
ug / kg , is highly effective .
3 – Supportive measures : elevation of
affected part , use elastic stockings or pressure
bandage , mechanical devices or boots that
apply intermittent pressure to promote
lymphatic flow .

20. 4 – Surgical treatment :
• Cosmetic surgery : to remove excess
connective tissue.
• Micro vascular surgery : small lymphatics
are anastomosed to a large central vein . It
can produce marked reduction in limb size.

21. Prevention & control
1 – Mosquito control e.g. spraying , use of
larvicides , insecticides .
2 – Mass treatment to eliminate source of
infection .