2. Prof.Dr/ Azza Elghareeb
TISSUE NEMATODA
Prof.Dr/ Azza Elghareeb

5. WUCHERERIA BANCROFTI Disease Bancroftian filariasis Elephantiasis.
Distribution
Africa, Asia and parts of South America. In Egypt; cases are detected in Kalyobia, Dakahlia, Sharkia, Cairo, Giza and Assiut.
Life Cycle
1- The adults live in the lymphatics of man (no reservoir host).
2- Microfilariae laid by the female reach the blood by migration through the wall of the lymphatics to the neighbouring small blood vessels.
3- Microfilariae gradually appear in the peripheral blood by night (nocturnal periodicity) reaching maximum about midnight (10 pm – 2 am), and gradually disappear by day time.

6. 4- The microfilariae are ingested by the mosquito intermediate host with its blood meal. Species of the genera Culex, Aedes and Anopheles act as vectors. In Egypt it is culex pipiens.
5- In the mosquito's stomach, the microfilaria loses its sheath, penetrates the gut wall and invades the thoracic muscles within 24 hours.
6- There it settles and moults assuming a short stout sausage shaped larvae (200x15 u).
7- After a few days it moults again (300x20 u).

7. 8-. About the tenth day the larva becomes long and slender (2000x20 u)
8- About the tenth day the larva becomes long and slender (2000x20 u). The filariform larvae (the infective stage) migrates from the thorax to the head, reaches the proboscis and enters the labium.
9- When the mosquito bites man, the infective larva attracted by warmth of the skin, pierce the labium and penetrate the skin or enter the bit wound.
10- Larvae pass to the lymphatic vessels and nodes where they grow to maturity in 6 to 12 months. They live and produce microfilaria for 5 to 10 years. Microfilaria live for 2 years.

8. Pathogenesis and Clinical Picture
I. 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 microfilariae and a low grade eosinophilia.

9. II. 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.
1- Filarial or elephantoid fever.
Recurrent attacks of fever with rigors ends with sweating (lasts few hours to several days).
2- Recurrent attacks of lymphangitis & lymphadenitis mainly of the legs & genitalia.

10. The legs show: Raised, red, hot, swollen & tender streaks
The legs show: Raised, red, hot, swollen & tender streaks. Bacterial & fungal super-infection.
The genitalia show:
Funiculitis: Inflammation of the spermatic cord
Orchitis: inflammation of the testis
Epididymitis: Inflammation of the epididymis
Epididymo-orchitis: Inflammation of the epididymis & testis.

12. Diagnosis
I. Clinical History
Presence of history of exposure to mosquitoes in an endemic area, together with clinical findings.
II. Laboratory investigations
1- Blood examination for microfilariae.
2- Polycarbonate filters (Nucleopore) technique: the microfilarae are trapped on the filter after the RBCs have been lysed by 3% acetic acid. The 3 to 5um pore size filters may be examined directly on a microscope slide because they are transparent when wet.

13. 3- Knott's concentration technique: add 2 ml blood to 10 ml 2% formalin, leave for 10 min then centrifuge and examine sediment either as a direct wet film or after staining with methylene blue.
4- Hetrazan provocation test: microfilariae may be demonstrated in blood at daytime by administration of 100 mg of diethylcarbamazine orally, 45 to 60 minutes before the blood specimen is taken.
5- Serologic test: detection of antibodies to filarial antigen may be of diagnostic value when microfilariae cannot be found

14. Intradermal test: skin test using antigen from dog heartworm, Dirofilaria immitis, is group-specific for filarial infections.
6-Detection of microfilariae in chylus urine or hydrocele (after dissolving chyle with ether).
III. Detection of adults in lymph node biopsy
IV. Imaging techniques
• Lymphoscintography:
Shows lymphatic dilatation. Soluble or fine colloidal material is injected interstitially. They will be taken up into the lymphatic vessels then into the draining lymph node.
• Ultrasonography:
Shows adults in lymphatics (when viable they give filarial dance sign).

15. Treatment
1- Diethylcarbamazine (DEC, Hetrazan): the drug is effective in killing microfilariae (rapidly) and adults worms (slowly), can be given orally in dosage 2 mg/kg t.i.d. for 12 days.
2- Ivermectin: Taken as single oral dose 200 µg/kg, is highly effective.
3- Supportive measures: Elevation of affected part, use elastic stockings or pressure bandaging, mechanical devices or boots that apply intermittent pressure to promote lymphatic flow.

16. 4- Surgical treatment:
a. Cosmetic surgery: to remove excess connective tissue.
b. Microvascular surgery: small lymphatics are anastomosed to a large central vein. It can produce marked reduction in limb size.
Prevention and Control
1- Mosquitoes control e.g. spraying, use of larvicides, insecticides.
2- Mass treatment to eliminate source of infection.

17. WUCHERERIA or BRUGIA MALAYI
Comparison between Wuchereria bancrofti and Brugia malayi