Filarial worm(丝虫)

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 Dipetalonema streptocerca Dipetalonema perstans Mansonella ozzardi Non- pathogenic

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

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

Morphology ADULTS: 2 cm – 120 cm (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 (150-350 μ long) - adults 2 cm – 120 cm (4 – 10 μ wide) ADULTS: 2 cm – 120 cm (4 – 10µm wide) W. B. Female ~105mm; Male ~42mm B. M. Female ~58.5mm; Male ~23mm

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

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 244-296x7 Smaller 177-230x5-6 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

Life Cycle

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

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

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

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

chyluria

Filarial hydrocele hydrocele testis Lymphocele of the right spermatic cord

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.

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

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

Epidemiology

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

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?

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

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

Onchocerca volvlus Onchocerca nodule

Onchocerca volvlus

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

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

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

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

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

Loa loa Cabalar swelling

Loa loa Loa loa adult in Calabar swelling x section

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

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

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.

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:

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