Filarial worm( 丝虫 )

1. Filarial worm(丝虫)

2. General Introduction Wuchereia bancrofti Brugia malayi Brugia timori Onchocerca volvulus (river blindness - black fly) Loa loa (eye worm - deer fly) Dipetalonema streptocerca Dipetalonema perstans Mansonella ozzardi

4. General Introduction • Roundworm • Adult filaria live in body cavities, lymphatics, and subcutaneous tissues • Embryos (microfilaria) live in blood or dermis • All require an insect vector

5. Wuchereia bancrofti(班氏吴策线虫) & Brugia malayi (马来布鲁线虫)

6. Morphology • ADULTS: 2 cm – 120 cm (4 – 10µm wide) • W. B. Female ~105mm; Male ~42mm • B. M. Female ~58.5mm; Male ~23mm

7. Morphology • Microfilaria: • 150-350 µm long head tail

8. Morphological differences between W.bancrofti & B. malayi microfilariae w.bancrofti B.malayi

9. Life Cycle

10. LifeCycle • Host: • W. bancrofti : human • B. malayi : human and reservior host • Residing place (adult worm): lymphatics • W. bancrofti: lymphatics of limbs and genital system • B. malayi: lymphatics of limbs • Infective stage：Third-stage filariform larvae (L3) • Intermediate host：mosquito • W. bancrofti: culex (Culex pipiens pallens, C. fatigans) • B. malayi: anopheles ( A. sinensis) • The larvae only undergo growth but no propagation there • Diagnostic stages: microfilariae

11. nocturnal periodicity • The phenomena that the presenting of microfilariae in the peripheral blood is very low in density at daytime but the number of microfilariae gradually increase from evening to early next morning. This periodicpattern was called nocturnal periodicity. The microfilariae mostly stay in the pulmonary capillary vessels during the day. • The peak time of microfilariae in the peripheral blood is: • W. bancrofti: 10pm – 2am • B. malayi: 8pm –4am

12. Clinical manifestations • Wuchereria bancrofti • Asymptomatic (incubation) • Inflammatory - lymphangitis (acute) • arms 25% • legs 11% • epididymitis, funiculitis 42% • ‘filarial fevers’ • Orchitis • filarial abscess

13. Clinical manifestations • Wuchereria bancrofti • Obstructive • elephantiasis • chyluria • hydrocele elephantiasis

14. chyluria

15. Filarial hydrocele • Lymphocele of the right spermatic cord • hydrocele  testis

16. Clinical manifestations Brugia malayi • commonly same with that of W. bancrofti, but hydrocoele and chyluria are rarely seen. • Elephantiasis due to Brugia malayi, complicated by severe dermatitis and secondary bacterial infection.

17. Diagnosis • Direct examination • Thick blood smear • Thin blood smear • Make sure to take the peripheral blood at proper time • Knotts concentration technique: lyse the blood cells and centrifuge (1~2ml of blood from vena) • Immunological methods: • Intra-dermal tests using antigens for early infection • ELISA for detecting specific antigen or antibody

18. Epidemiology • Source of infection: carrier, patients, reservoir host for Brugia Malayi • Vector: mosquitoes including culex, anopheles and Aedes • Distributed in tropical and subtropical region, Brugia Malalyi only in Asia

19. Epidemiology

20. Prevention • Mass chemotherapy: • hetrazan(diethylcarbamazine，DEC) • Control of and protection from mosquitoes • Use of screens • Use of insect repellents • Use of insecticides

21. QUESTIONS • 1. MCQ: • The vector of B. m and W.b is: A.mosquito B.lice C.sandfly D. termite • 2. Fill in the blanks: • The infective stage of B. m is _____ • 3. Explain the definitions： • nocturnal periodicity • 4. Essay questions: • What is the consequence of W. b infection?

22. Onchocerca volvlus(旋盘尾丝虫) Black fly(蚋) River Blindness

23. Onchocerca volvlus • Pathogenic stage: microfilariae • Intermediate host：blackfly (Simulium spp.) • Severe symptoms due to microfilariae in skin and in the eye • Adult worms in nodules cause insignificant pathology

24. Onchocerca volvlus Onchocerca nodule

25. Onchocerca volvlus

26. Onchocerca volvlus • The world’s 2nd leading infectious cause of human blindness -- onchocerciasis

27. Epidemiology • Approximately 96% in tropical Africa with significant number in the highland of Western Guatemala, Colombia and northeastern Venezuela, even Mexico

28. Prevention • Treatment of the patients • Surgical treatment (remove the adult worms in the nodules) • Chemotherapy: Ivermectin (effective to kill microfilariae) • Control of insect vector population • Protective netting and screening to shield individuals

29. Loa loa Chrysops (deer fly,斑虻) The eye worm

30. Loa loa ●Pathogenic stage: Adult worm ●Intermediate host：Chrysops ●Mildly pathogenic ●Adult worms wander through out the body (1.5cm/min) and cause pathology The most troublesome infection sites --conjunctiva

31. Loa loa Cabalar swelling

32. Loa loa Loa loa adult in Calabar swelling x section

33. Loa loa Epidemiology • Loaiasis is now limited to the African equatorial rain forest and southern Sudan • Infection rates are highest in regions with muddy ponds and swamps

34. Prevention • Treatment of the patients • Surgical removal of wandering adult worms from the conjunctiva is advisable • Chemotherapy: Diethylcarbamazine/Ivermectin (effective to kill microfilariae), but may both have severe side-effects • Control of insect vector population • Protective netting and screening to shield individuals

35. HYPERACTIVE CHILD SYNDROME HISTORY A mother brought her 7-year-old son to the psychiatrist because he had some behavioral problems in school and at home. She stated that he was very irritable and inattentive and that his attention span was very short. In addition, he begun to experience insomnia and had episodes of enuresis. He was unable to sit still, had lost some weight, and his appetite was not as good as usual. His birth and development were normal. The astute psychiatrist inquired further and learned that the child was also experiencing perianal itching. He performed a swab of the perianal area. The results confirmed his suspicion. The child was treated with piperazine and all his symptoms disappeared.

36. The child gets infected with: A. ascaris B. whipworm C. pinworm D. hookworm • He may acquire the infection from: • The plan of treatment should include:

37. Questions: • Why A. lumbricoides infection distributed so widely? • Why hookworms can cause anemia ? What are the characteristics of the anemia? • Geo-helminth • Bio-helminth