Filariasis

Filarial worms ,life lycle and laboratory diagnosis.

1. FILARIASIS By: Rajesh B.K BScMLT 4 th Batch Chitwan Medical College, Bharatpur-10,Chitwan 11/3/2016 1

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3. AIM To know the morphology ,life cycle, pathogenicity and lab diagnosis of Wucheria bancrofti . 11/3/2016 3

4. OUTLINE OF PRESENTATION Introduction Classification Wucheria bancrofti Morphology Mode of Transmission Life Cycle Pathogenesis Signs and Symptoms Laboratory Diagnosis Epidemiology Prevention and control Pictures 11/3/2016 4

5. INTRODUCTION Filariasis is the pathological condition caused by infection of Filarial nematodes transmitted by different vectors. Infection occurs in blood vessels, lymphatic system, connective tissues and serous cavities of man. It is the disease of Tropical warm lands. 11/3/2016 5

6. CLASSIFICATION Filariasis is classified depending on the area of the body which the worms mainly affect. Its classifications include: 1. Lymphatic Filariasis -affects the lymphatic system. -can result to a more serious complication such as enlargement of body parts. -can cause pain and permanent disability -caused by Wucheria bancrofti , Brugia malayi , Brugia timori . 11/3/2016 6

7. 2. Subcutaneous Filariasis -affects the subcutaneous area of the skin. -caused by Loa loa , Onchocerca volvulus , Mansonella streptocerca . 3. Serous Cavity Filariasis -affects the abdomen’s serous cavity. -caused by Mansonella ozzardi , Mansonella perstans . 11/3/2016 7

8. Lymphatic Filariasis Three types of worms can cause the disease : Wucheria bancrofti , Brugia malayi , Brugia timori The worms damage the lymphatic system. Wucheria bancrofti is the most common. 11/3/2016 8

9. Wucheria bancrofti It is the most common and widespread species of Filaria infecting humans. HABITAT : The adult worm lives in the lymph nodes and lymphatic vessels of human only. Brancroftian filariasis is not a zoonotic disease since there is no animal reservoir. HISTORY : The larval forms of parasite (microfilaria) were first found by Demarquay (1863) in hydrocele fluid. The genus is named after Wucherer who found them in chylous urine in 1868 in Brazil. Lewis (1872) found them in human blood in Kolkata. Bancroft (1876) found the adult females in lymphatic abscess ,hence the specific name was given after the discoverer. 11/3/2016 9

10. MORPHOLOGY : Adult worms: -These are long hair-like transparent nematodes (often creamy-white in color). -They are filiform in shape and both ends are tapering. -The Male measures 2.5 to 4 cm in length by 0.1 mm in thickness. Its tail-end is curved ventrally and contains two spicules of unequal length. -The Female measures 8-10 cm in length by 0.3 mm in thickness. Its tail-end is narrow and abruptly pointed. The females are really ovo-viviparous (laying eggs with well developed embryos). The life span of the adult worms is about 5 to 10 years. 11/3/2016 10

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12. Embryos (Microfilaria) -Passing through lymph nodes, the actively motile embryos find their way by the main lymphatic trunks into circulatory blood. The embryo measures about 300 um in length by 6 to 7 um in breadth. When dead and stained with Romanowsky stains, the embryo shows the following morphological peculiarities : Hyaline Sheath ,Somatic cells or nuclei ,Granules (nerve ring ,anterior V-spot and posterior V-spot) and Genital cells (G-cells) . 11/3/2016 12

13. Nocturnal periodicity: The microfilariae of W. bancrofti take rest in the capillaries of lungs ,kidneys, heart and arteries during day time and invade peripheral circulation at night ,at night from 10 pm to 4am (Nocturnal periodicity). 11/3/2016 13

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15. Life Cycle :- Wucheria Bancrofti completes its life cycle in two hosts : Definitive host = Man Intermediate host = Female mosquito (mostly Culex , sometimes Aedes and Anopheles ) 11/3/2016 15

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17. In Intermediate host : - The sheathed Microfilaria is ingested by mosquito during its blood meal. - They cast off their sheath in the stomach within 15-30 minutes , penetrate the stomach wall within an hour or two and migrate to thoracic muscles where they mount and undergo development to 1 st ,2 nd and then to 3 rd stage (filariform) larvae. This actively motile 3 rd stage larva is infective form. Microfilaria does not multiply in mosquito and only one microfilaria develops into one infective larva only. -The infective larva is injected into man by mosquito during its blood meal and the life cycle is repeated. 11/3/2016 17

18. In Definitive host : - When the infected Culex mosquito (most common Culex fatigans ) bites a man ,the filariform larvae are injected into the blood stream. The larva reaches the lymphatic vessels and lymph nodes along the blood . They develop into adult worms in 5-18 months in lymphatics and live there. The adult male fertilize the females which produce larvae. A new generation of microfilariae is emitted which passes either through the thoracic duct or the right lymphatic duct ,to the venous system ,and pulmonary capillaries and then to the peripheral circulation ,thus completing the cycle. 11/3/2016 18

19. Pathogenesis and Clinical disease : Lymphatic Filariasis (a) Early infection : Patients experience fever, lymphangitis, headache, nausea and urticaria. (b) Chronic infection: Repeated attacks cause lymphatic damage which progressively leads to lymphadenitis, lymphedema and other complications. 1. Inflammation : Allergic lymphangitis results from presence of masses of adult worms in the lymphatics. 2. Dilatation of lymphatics : The presence of adult worms cause lymphadenitis and duct dilatation ,leading to lymph retention in the areas drained by the lymph nodes and lymph vessels. Dilatation of lymphatics leads to lymphangiovarix. Rupture of lymphangiovarix results in: 11/3/2016 19

20. Lymphorrhagia : Lymph scrotum ,Lymphocele ,Lymphuria. Chylorrhagia (obstruction in the chyle-bearing vessels ,thoracic duct) : Chylocele ,Chyluria , Chylous ascites. Hydrocele : It is a common manifestation of filariasis .Accumulation of fluid occurs as a result of obstruction of the lymph vessels of the spermatic cord and also due to exudation from the inflamed testis and epididymis .Hydrocele fluid is usually clear and straw colored,occasionally it may be milky ,cloudy or haemorragic . Occasionally ,the hydrocele assumes enormous proportion in association with Elephantiasis of Scrotum. 11/3/2016 20

21. 3. Elephantiasis :It is delayed sequel to repeated and progressive W. bancrofti infection . It is caused by: - mechanical blocking of the lumen of lymph vessels , - obliterative endolymphangitis due to endothelial proliferation and inflammatory thickening , - excessive fibrosis of lymphatic vessels , - fibrosis of afferent lymph nodes draining particular area. Lymphatic obstruction leads to swelling, fibrosis , and eventually elephantiasis. The skin surface becomes coarse with warty excrescences. Elephantiasis most commonly affects limbs, genital organs and breasts. 11/3/2016 21

22. B. Occult Filariasis : The term Occult Filariasis refers to a condition which is caused by a hypersensitivity reaction to microfilarial antigens and is characterized by massive eosinophilia (30-80%) ,hepatosplenomegaly and absence of Microfilaraemia. Adult female produces microfilaria in lymph node but they do not reach peripheral blood as they are destroyed in the tissues. Tropical Pulmonary Eosinophilia (TPE) : This is a manifestation of occult filariasis and is characterized by low fever ,loss of weight , paroxysmal cough with scanty sputum(may be blood-tinged) and splenomegaly. 11/3/2016 22

23. Laboratory diagnosis : Specimens :- Blood , Chylous urine ,Hydrocele fluid and Biopsied lymph node. MICROSCOPY: Definitive diagnosis is made by detection of microfilariae in a thick blood smear and chylous fluid. (a) Examination of Blood 1. Thick blood smear technique: -Smear made from two drops of deposit is stained by Leishman/Giemsa stain and examined microscopically. 2. Wet-slide preparation : -Two drops of deposit is mixed with equal volume of water (to lyse the red cells) on a slide. The preparation is covered with a coverslip and examined microscopically using low power (10x). 11/3/2016 23

24. 11/3/2016 24 Fig: Giemsa Stain of Microfilariae

25. (b ) Examination of Chylous fluid - Chylous fluid is creamy white and opalescent . Chyle consists of lymph and particles of digested fat (ether soluble). Procedure:- Urine is centrifuged at 2000 rpm for 10-15 minutes. The supernatant is thrown out and the deposit is mixed with equal volume of water and centrifuged again. The supernatant is discarded and wet preparation from deposit is placed on slide, covered by coverslip, examined for the presence of microfilariae. The deposit may be smeared on slide and stained by Leishman or Giemsa stain. 11/3/2016 25

26. (c) Examination of Biopsy specimens : -Adults filarial worms can sometimes be found in sections of biopsied lymph nodes as incidental findings. -This is not done for routine diagnosis. 2. Serological tests like ELISA test and IHA test can be used for detection of antibodies to larval antigens. 3. PCR assay for the detection of microfilariae infection of W. Bancrofti has been developed. 11/3/2016 26

27. 4. X-Ray examination shows calcified adult worm. USG can detect adult W. bancrofti in lymphatic vessels of scrotum in infected male and of breast in infected female. 11/3/2016 27

28. TREATMENT Diethylcarbamazine (DEC) is the drug of choice ,because it is effective against both adults and microfilariae. Ivermectin destroys microfilariae ,but not adults. 11/3/2016 28

29. PREVENTION Destruction of breeding sites of vectors. Using bed nets while sleeping. Applying repellant creams on skin. 11/3/2016 29

30. PICTURES 11/3/2016 30 Source : Epidemiology disease control Nepal

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36. Conclusion: W. brancrofti causes bancroftian filariasis ,elephantiasis. It is the most common and widespread species of filarial infecting humans. Completes its life cycle in two host :Man and Female mosquito. 3 rd stage larva is infective form. Lab diagnosis includes: -Detection of microfilaria in blood, urine and hydrocele fluid. -Demonstration of adult worm in biopsy specimen. -Immunudiagnosis: detection of antigen and antibody. 11/3/2016 36

37. References: Textbook of Medical Parasitology ,P. Chakraborty. Parasitology 13 th edition ,K.D. Chatterjee. 11/3/2016 37

38. THANK YOU FOR YOUR ATTENTION 11/3/2016 38