Filariasis ( wuchereria bancrofti)

( wuchereria bancrofti) FILARIASIS FOR M.Sc students

1. BANCROFT’S FILARIASIS SUBMITTED TO DEPARTMENT OF ZOOLOGY ISABELLA THOBURN COLLEGE LUCKNOW

2. INTRODUCTION Filariasis is the term for a group of disease caused by parasitic nematodes. Filariasis caused by nematodes that live in the human lymph system, Bancroftian filariasis or Lymphatic filariasis. Causative organism- filarial worm Wuchereria bancrofti (Cobbold 1877) Elephantiasis is the end result of disease. Cutaneous and subcutaneous tissue enlarge and harden in areas where lymph has accumulated. Usually occurs in lower extremities.

3. Wuchereria bancrofti Common name- Bancroft’s filaria Bancroft (1876-77) demonstrated adult female and Sibthorpe (1888) first found adult male. Manson (1878) first demonstrated the culex mosquitoes as the INTERMEDIATE HOST. Geographical distribution Very widespread and important human parasite in worm countries. In Africa (Mediterranean and east west coastal areas) In Asia (coasts of Arabia, India, Malaya and north to china. Habitat Filarial worm inhabit the lymphatic vessels, especially the lymph nodes of man and other vertebrates. Microfilariae are found in peripheral blood (also found in chylous urine or hydrocele fluid)

4. Morphology Adult worm Third stage larva Microfilariae (first stage larva)

5. Adult worm Long hair like transparent nematodes Creamy white in colour. Filiform in shape, both ends are tapering Male- 2.5-4 cm in length and 0.1mm thickness Tail end is curved ventrally contain 2 spicules Female- 8-10cm in length and 0.2-0.3mm thickness Tail end is narrow and abruptly pointed Ovo-viviparous, though liberating active embryos. Male and female coiled together, can be separated with difficulty Life span is long, 5-10 years Wuchereria bancrofti

6. MICROFILARIAE First stage larva Location- peripheral blood and often in hydrocele fluid and chylous urine Size- 244-296 micrometre in length and 7.5-10micrometre in diameter Body- transparent and colourless, covered by hyaline sheath They can live up to 70 days in human blood Microfilarial periodicity- Nocturnal periodicity Present in high number in peripheral blood at midnight Eg- Brugia malayi Diurnal periodicity Present in greatest number in peripheral blood during day time Eg- Loa loa MORPHOLOGY OF MICROFILARIAE

7. Third stage larva Infective form of the filarial worm in human. Shape- elongated, Filiform Size- 1.4-2 micrometre in length and 18-23 micrometre in breadth MICROFILARIAE IN BLOOD FILM

8. LIFE CYCLE DEFINITIVE HOST- Man (In human lymphatic system) INTERMEDIATE HOST- Mosquitoes Culex quinquesfasciatus Anopheles Aedes Culex quinquesfasciatus Aedes Anopheles

9. PATHOGENICITY INFECTION- Wuchereriasis (commonly called filariasis) MODE OF INFECTION- Inoculative method, through the bite of mosquito TRANSMITTING AGENT- Female mosquito(Culex, Aedes, A nopheles) INFECTIVE FORM-Third stage larva PORTAL OF ENTRY-Skin SITE OF LOCALIZATION-Lymphatic system of superior or inferior extremities INCUBATION PERIOD- About 1 to 2 years(3 rd stage infective larva grows to adult form)

10. CLINICAL MENIFESTATION LYMPHATIC FILARIASIS OCCULT FILARIASIS endemic normal Asymptomatic stage Acute filariasis Chronic filariasis Non-filarial elephantiasis Tropical pulmonary eosinophilia (TPE)

11. LYMPHATIC FILARIASIS ENDEMIC NORMAL In the area of endemic filariasis, a certain proportion of the population living in these area do not show any overt clinical manifestation of disease Difficult to know, people are infected or not ASYMPTOMATIC STAGE Have microfilariae in their blood but do not show any symptoms of disease Remains asymptomatic for years or even life ACUTE FILARIASIS Filarial fever and lymphadenitis (major symptoms) May occur several times a year

12. ELEPHANTIASIS

13. THANK YOU…

14. Hydrocele- obstruction of the lymph vessels of spermatic cord and inflammation in testes Elephantiasis- affected part become enormously enlarged (tumour like solidity) The surface of skin become rough and papliomatous Hairs become rough and sparse CHRONIC FILARIASIS Hydrocele elephantiasis Lymph varices- varicosity of lymphatic v essels (abdominal and genital area) Chyluria- escape of chyle through the urine (rapture of varicose chyle vessels) Microfilariae are detected in chylous urine and peripheral blood NON- FILARIAL ELEPHANTIASIS Lymph varices chyluria

15. OCCULT FILARIASIS Hypersensitivity reaction of the host to Microfilarial antigen Microfilariae are not detected in peripheral blood Examples- tropical pulmonary eosinophilia (TPE), Less frequently arthritis TROPICAL PULMONARY EOSINOPHILIA (TPE) Eosinophilic lung, Weingarten’s syndrome Characterised by low fever, loss of weight, paroxysmal cough with scanty sputum, dyspnoea and splenomegaly Chest radiography shows increased branchiovascular marking or military “mottling” in lung fields Microfilariae may b e demonstrated in tissue obtained by lung biopsy

16. EPIDEMIOLOGY GEOGRAPHICAL DISTRIBUTION- topics and subtropics of Asia, Africa, South America Periodic nocturnal W. bancrofti is the most widespread Endemic in India, China and other countries of South-East Asia RESERVOIR HOST AND TRANSMISSION OF INFECTION Infected person with circulating microfilariae are the chief source of reservoir and infection Man- to- man transmission by the bite of mosquito

17. DIAGNOSIS DIRECT EVIDENCES Microfilariae (sheathed having tail - tip free from nucleus) In peripheral blood In chylous urine In hydrocele fluid 2. Adult worm In biopsied lymph nodes Calcified worm by X-ray INDIRECT EVIDENCES Allergic test Blood examination(eosinophilia 5 to 15%) Intradermat test- an immediate hypersensitivity reaction Immunological test (complement fixative test) A sensitive test for loiasis and occult filariasis Other tests- Biopsy (for purely diagnostic purpose) Serological diagnosis (ELISA, RIA) Trop Bio Test (detection of adult worm infection not depends on Microfilarial periodicity) PCR assay (detection of Microfilarial infection) X-ray examination ( shows calcified adult worm)

18. TREATMENT Diethyl carbamazine (DEC) Kills mainly microfilariae Most effective against 3 rd and 4 th stage larva Adenolymphangitis decreases significantly Cheap, effective and safe with few side effects (fever, chill, headache etc.) DOSE 1 st day - 50mg after food 2 nd day - 50mg three times daily 3 rd day - 100mg three times daily 4 th day – 21 st day - 5mg/kg/day in three divided dose Other drugs Iveemeciin (150ug/kg body wt., destroy microfilariae, no mocrofilaricidal effect) Lavamisole Mebendazole Centprazine (CDRI Lucknow)

19. PREVENTION AND CONTROL Mosquito control clinical control by spraying insecticides (DDT, malathion) Biological control by the use of carnivorous bacteria(Bacillus sphaericus ), carnivorous fishes ( Poecilia reticulata ) Environmental control by efficient drainage and sewage system Chemotherapeutic control Reduce morbidity du to filariasis by treating clinical case Lower transmission by treating the case of crofilaraemia Interrupt transmission of the infection Based on mass or selective treatment of the cases by administering DEC