1. Filarial worm(丝虫)

2. General Introduction Wuchereria bancrofti Brugia malayi Brugia timori
Onchocerca volvulus (river blindness - black fly)
Loa loa (eye worm - deer fly)
Dipetalonema streptocerca
Dipetalonema perstans
Mansonella ozzardi
Dipetalonema streptocerca
Dipetalonema perstans
Mansonella ozzardi
Non- pathogenic
William C. Campbell
Satoshi Omura
2015 Nobel Prize in physiology and Medicine
Avermectin

3. 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
Dipetalonema streptocerca
Dipetalonema perstans
Mansonella ozzardi
Non- pathogenic

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

5. Morphology ADULTS: 2 mm – 120 mm (4 – 10µm wide)
roundworm
-Adult filaria live in body cavities, lymphatics,
and subcutaneous tissues
-embryos (microfilaria) live in blood or dermis
-all require an insect or crustaean vector
-microfilaria ( μ long)
- adults 2 cm – 120 cm (4 – 10 μ wide)
ADULTS: 2 mm – 120 mm (4 – 10µm wide)
W. B. Female ~105mm; Male ~42mm
B. M. Female ~58.5mm; Male ~23mm

6. Morphology Microfilaria: 150-350 µm long head tail
Distribution of internal nuclei
head
tail

7. Morphological differences between W. bancrofti & B
Morphological differences between W. bancrofti & B. malayi microfilariae
W.bancrofti
B.malayi
W. bancrofti
B. malayi
Size (µm)
Larger x7
Smaller x5-6
Body curvature
Graceful, gently curved
Irregular, kinky curves
Cephalic space
Shorter
longer
Somatic nuclei
Equal sized, visualized individually
Unequal sized, tightly packed
terminal nuclei No
Two

8. Life Cycle

9. Life Cycle Host: Residing place (adult worm): lymphatics
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

10. 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 periodic pattern 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

11. Clinical manifestations
Wuchereria bancrofti
Asymptomatic (incubation)
Inflammatory - lymphangitis (acute)
arms 25%
legs 11%
epididymitis, funiculitis 42%
‘filarial fevers’
Orchitis
filarial abscess
A hydrocoele is a pocket of watery liquid that has built up around your testicle
chyle
[kail] n.
[生物]乳糜
Milky” urine: a case of chyluria

12. Clinical manifestations
Wuchereria bancrofti
Obstructive
elephantiasis
chyluria
hydrocele
A hydrocoele is a pocket of watery liquid that has built up around your testicle
chyle
[kail] n.
[生物]乳糜
Milky” urine: a case of chyluria
elephantiasis

13. chyluria

14. Filarial hydrocele hydrocele testis
Lymphocele of the right spermatic cord

15. 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.

16. Diagnosis Direct examination Immunological methods: 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

17. 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

18. Epidemiology

19. Prevention Mass chemotherapy:
Hetrazan(diethylcarbamazine，DEC)
Avermectin
Control of and protection from mosquitoes
Use of screens
Use of insect repellents
Use of insecticides
乙胺嗪(海群生）

20. QUESTIONS 1. MCQ: A.mosquito B.lice C.sandfly D. termite
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?

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

22. Pathogenic stage: microfilariae
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

23. Onchocerca volvlus
Onchocerca nodule

24. Onchocerca volvlus

25. Onchocerca volvlus
trachoma, the leading infectious cause of blindness in the world
The world’s 2nd leading infectious cause of human blindness -- onchocerciasis

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

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

28. Loa loa（罗阿罗阿丝虫）
Chrysops (deer fly,斑虻)
The eye worm

29. Loa loa The most troublesome infection sites -- conjunctiva
●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

30. Loa loa
Cabalar swelling

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

32. 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

33. 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