Onchocerca Volvulus PDF

[email protected] ONCHOCERCA VOLVULUS Jur blindness (river blindness) INTRODUCTION about 96% of all cases are in Africa In Sudan in Northern Sudan in Abo- [email protected] hamad ,Nahr Atbara and Nahr Eljour (Jour blindness). The infective lar...

[email protected] ONCHOCERCA VOLVULUS Jur blindness (river blindness) INTRODUCTION about 96% of all cases are in Africa In Sudan in Northern Sudan in Abo- [email protected] hamad ,Nahr Atbara and Nahr Eljour (Jour blindness). The infective larvae (L3) are normally transmitted by the bite of Black flies (Simulium damnosum) which found in near fast running rivers adult encapsulated within nodules in subcutaneous tissues [email protected] [email protected] morphology microfilariae 300 µm in length and 0.8 µm in diameter. The microfilariae are sheath less with sharply pointed, curved tails, there is no nuclei in the end of the tail, head end is slightly enlarged [email protected]  adult females measure 45-50 cm by 300 µm, males 20-40 mm by 200 µm. Adults live for 8- 10 years in nodules.(onchocercoma).  They bear transverse striations on the cuticle with annular and oblique [email protected] thickening. This helps in differentiating from other filarial worms [email protected] Clinical presentation One early sign of infection with Onchocerca is the raised nodules that can be seen under the skin (onchocercoma). [email protected] 2- inflammatory dermatitis also occur as: a- papules b- tissue paper skin c-hypo pigmentation (leoperal skin and lizard skin). d- thickening of the skin ( elephant skin). [email protected] e- hyper pigmentation, in on limb (Swada or black disease) first reported in Yemen. Loss of elasticity when skin around groin lead to hanging groin. [email protected] Ocular onchocerciasis: when microfilaria in the skin of the face migrate in to the eye. The microfilaria may be found in cornea and anterior chamber of eye. It do photophobia, lacrimation, chronic conjunctivitis, opacity, adhesive or synechiae then blindness [email protected] LAB DIAGNOSIS: 1- Skin snips: by using sterile needle, cut apiece of skin in NS, the microfilaria emerge from the skin. [email protected] 2-ELISA 3- PCR 4- Onchocerca skin card to detect IgG SKIN SNIPS TECHNIQUE: Most common sites: Both iliac crests or sometimes from  calves and the shoulders Procedure: Skin is lifted by a needle and a small piece  (1 to 3 mm) is excised with a sterile scalpel blade After incubating the biopsy tissue in saline, microfilariae  emerge from the skin (60% within 30 minutes, 75% in 24 hours) The movement can be seen by direct microscopy. However,  differentiation from other microfilariae can be done following Giemsa or hematoxylin and eosin (H & E) staining Quantification of microfilariae can be done (number of  microfilariae per mg of skin) which is an accurate tool to measure the endemicity of infection in the community. SKIN SNIPS TECHNIQUE: [email protected] 5-Mazzotti test:  The patient may be given 50 mg DEC orally. If microfilariae are present, a severe itching reaction will occur within 2 hours. This is caused by an allergic reaction to the proteins [email protected] released after the rapid breakdown of microfilariae. Because this is very unpleasant, this test should be used only when strictly necessary. Topical use of a DEC-containing cream (Nivea) has also been described (DEC patch test), in response to which a limited local skin reaction can occur.  [email protected]