Subcutaneous fillriasis (onchocerciasis) tramited by biting flies. LIFE CYCLE

Subcutaneous fillriasis (onchocerciasis) tramited by biting flies. LIFE CYCLE - Adult female worms situated in various (issues in the human host produce embryonic mcrofilariae which are sucked up by mosquitoes or bung flies during a blood meal Microfilariae develop to their larval stage in the insect vector and are passed on to a new human host in which the final maturation to adult worme takes place Adult filarial worms do not multiply in man Periodicity of microfilariae - in most endemic areas the mcrofilarriae of W bancrofit appear in greatest numbers in peripheral blood in the night between 10 p.m. and 2 a.m. during the day they return to the pulmonary capillaries Mcrofilariae of B. malayi exhibit either nocturnal periodcity, or dumal periodcity with ,a peak In the early evenings Lymphatic filarlasis - can be caused by Wuchereria bancrofti, transmited by Anopheles. Culex and Aedes mosquitoes. Brugla malayi, transmited by Mansonia and Anophsles mosquitoes brugia timori, transmited by Manaonia and Anopheles mosquitoes Clinical features - Two syndromes - (a) Lymptiatic frlariasis caused by adult or developing adult worme, producing episodic inflammation of lymphatic vessels, followed by obstrctive lymphatic. lesions (b) Syndrome - caused by immune hyparresponsiveness of human host against microfilaria, producing occut fileriasis (circulating filarial antigens or microfilaraemia). ACUTE CLINICAL FEATURES 1 Filarial lever-Attacks of fever with rigors and with headache and rnalaise, lasting- 3-s recurring at Intervals. and sometimes associated with an attack of filarial adenolymphangitis. 2. Filarial lymphangitis and lymphadenitis - fa) Acute lymphangitis - in extramities with lever with riugors and toxemia. The tender inflamedly lymphatics are seen as red streaks. it may be accompanied by itchy, irregular erythamatous swelling ot the skin scattered over the body, which may sometimes appear In absence of local lymphangitis Lymphatics anywhere in the body may be Involed, Those of spermatic cord and testis are especially susceptible (b) Lymphadanltis - occurs episodically. most often in inguinal area. Other sites are medial aspect of leg. axilla or medial side of arm. Occasionally in the breast Invoivement of intra-abdominal Iymphatic may produce clinical appearances of acute abdomen Secondary grarn-postiive bacterial infections cause suppurative lymphadenitis or abscess formation particullarly in the breast, or in muscle resembling tropical pyomysitis. CHRONIC CLINICAL FEATURES (late obatructive phase) 1. Hydrocele - is conmon with w bancroti. 2. Lymph oedema - is most common in lower limbs but also occurs in the upper limbs or the breast .3. Elephantiasis - results from further progression with drmatasclerotic and papillomatous changes superimposed Lymphoedema and elephantlasis are mush more pronounced on one side of the body, possibly because the parasites tend of congregate Thckening of both skin and overlying tissues. One or both legs and scrotum most commonly involved Upper extremitles, breast and labia may also be affected. 4. Finally rupture of lymphatic varices - into renal pelvis or