Filarial Worm (Filariae) Filarial worm are tissue residing nematodes. Around the world, there are...
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Transcript of Filarial Worm (Filariae) Filarial worm are tissue residing nematodes. Around the world, there are...
Filarial Worm (Filariae)
Filarial worm are tissue residing nematodes. Around the world, there
are eight species, which could infected human being.
Species Location Vector
Wuchereria bancrofti ( 班氏 ) lymphatic system mosquito
Brugia malayi ( 马来 ) lymphatic system mosquito
Brugia timori ( 帝汶布鲁 ) lymphatic system mosquito
Onchocerca volvulus ( 旋盘尾 ) subcutaneous tissue blackfly
Loa loa ( 罗阿罗阿 ) subcutaneous tissue horsefly
Dipetalonema streptocerca ( 链尾 ) subcutaneous tissue gnats
Dipetalonema perstans (常现) body cavities
Mansonela ozzardi (奥氏) body cavities
Wuchereria bancrofti & Brugia malayi
世界性分布,蚊是主要传播媒介They are the most widely distributed filariae that are transmitted
by mosquitoes.
Morphology
成虫 (adult)
They are elongated, thread-like worms. The adult female worm
of W.bancrofti is larger than B.malayi.
Female produce larvae known as microfilariae.
微丝蚴 (microfilariae)
头隙 , 体核 , 尾核
They are elongated and sheathed, with blunt anterior end
and pointed caudal end. A large number of nuclei could
be seen in the body after staining.
班氏微丝蚴与马来微丝蚴的区别
班氏 马来大小 较大 较小
体态 柔和 僵硬头隙 呈方形 长方形体核 圆形,大小一致, 卵圆形,大小不一
清晰可数 排列密集尾核 无 有
W.bancrofti B.malayi
Length ( m)
Diameter ( m)
Body curves
Cephalic space
Somatic nuclei
Caudal nuclei
200-300
8
regular, smoothly curved
small
well separate
none
220-250
6
irregular twisted
large
over lapped
two
Differential characteristics of microfilariae between W.bancrofti and B.malayi (1)
区别的意义1. 致病性不同 班氏大2. 分布不同 班氏分布广3. 药敏性不同 马来对药敏感
difference in pathogenicity
W.bancrofti more heavy
difference in distribution
W.bancrofti worldwide distributed
difference in drug sensitivity
B.malayi is more sensitivity in drug
在蚊体内有腊肠期蚴 ; 丝状蚴 ,
感染期幼虫为丝状蚴 (filariform larva)
microfilariae in the mosquito first into a rhabditiform larva
(Sausage shaped larva) then into an filariform larva------
infectious stage
Life cycleThe life cycle of two species are similar. The larvae develop in the mosquito which acts as vector, and the adults develop in the human.
adlut microfilariae sausage shaped larva filariform larvalymphatic peripheral thoracic musculature labium of system blood of mosquito mosquito
human infected
larva enter the lymphatic system
成虫 微丝蚴 腊肠期幼虫 丝状蚴( 淋巴系统 ) ( 血液 ) ( 蚊胸肌 ) ( 蚊下唇 )
蚊叮
吸血
在蚊体内的发育 , Development in the mosquito: The microfilariae ingested by the mosquito along with its blood meal migrate to its muscles.
After 6 to 14 days of development, the larva force their way out of muscles, migrate to the proboscis (labium).
During the blood meal the developed larva emerge from proboscis onto the skin of the new host.
# some factors effected the development of larva in mosquito vectorW.bancrofti: Culex 淡色库蚊 , 致倦库蚊B.malayi Anopheles, Aedes 中华按蚊 , 嗜人按蚊 , 东乡伊蚊
在人体内的发育 Development in the human
On penetrating the skin through the bite wound, the larva pass to the
lymphatic vessels and nodes
After copulation, the female produces microfilariae in about 3 months
infection
The microfilariae migrate from the parent worm the through the walls
of the lymphatics to the neighboring small blood vessels or are carried
in the lymphatic circulation to the bloodstream
Microfilariae appear in the greatest number in the peripheral blood
between 8 pm and 4 am
nocturnal periodicity-------- the microfilariae, present in very
small numbers or often undetectablein the peripheral circulation
during the daytime, then appear in the greatest density at night,
when absent from the peripheral circulation the microfilariae
are found in the capillaries of the lung
夜现周期性 (nocturnal periodicity)
微丝蚴白昼滞留于肺血管内,夜晚则出现在外周血液的现象。
Microfilariae of Wuchereria bancrofti
Nocturnal periodicity of microfilariae
W.bancrofti B.malayi
Location
nocturnal
periodicity
reservoir host
deep or near surface
lymphatic system
10 pm—2 am
-
near surface
lymphatic system
8 pm—4 am
+
Differential characteristics of microfilariae between W.bancrofti and B.malayi (2)
致病 (Pathogenicity) 丝虫病主要是由成虫引起的
Filarial symptoms are caused mainly by the adult worms,
living as well as dead and degenerating
Microfilariae cause less pathology, although they have been associated
with tropical pulmonary eosinopholia granulomas of the spleen, and
allergic reactions following their destruction by drugs
Clinically, the disease can be divided into incubation, acute,
and chronic phase
Incubation phase: 1. asymptomatic and may last for a year or more 2. may include low-grade fever caused by lymphatic inflammation Acute phase: an allergic response to the products of dying and degenerating adult worms ------ lymphangitis, funiculititis, orchitis, epididymitis filarial fever
Chronic phase: repeated lymphangitis granuloma fibrosis obstruction of lymph vessels lymph varices rupture of lymphatic proliferation of connective tissues elephantiasis elephantiasis hydrocele testis W.bancrofti chyluria
淋巴 ( 结 ) 管炎 增生性肉芽肿 纤维化 ( 纤维组织增生 )
1. 淋巴液肿
(1) 象皮肿 (elephantiasis)
(2) 睾丸鞘膜积液
2. 乳糜尿
管道阻塞压力↑ 曲张破裂液体外溢
诊断
( 一 ) 病原诊断
1. 血检
2. 体液和尿液检查微丝蚴 Examination of blood thick blood film-----detected microfilariae lysed blood check -----concentrated Examination of aspiration ( induction) 3. 成虫检查 直接或以活检 Detection of adult worm ( 二 ) 血清学检查
( 三 ) 其他 mAb, ELISA, PCR
流行因素 Epidemiology
( 一 ) 分布:
世界性分布 W.bancrofti is worldwide distributed
B.malayi is restricted to Asia
( 二 ) 流行环节
1. 传染源 Source of infection: patients, infected persons
2. 传播媒介 :蚊是主要传播媒介,主要蚊媒如下:
Transmission: mosquito Culex Anopheles, Aedes
班氏丝虫 马来丝虫
W.bancrofti: B.malayi
淡色库蚊
致倦库蚊
嗜人按蚊
中华按蚊
东乡伊蚊
3. 易感人群
4. 影响因素
防治原则 Treatment & Prevention
( 一 ) 普查普治
海群生 diethylcarbamzine (DEC) hetragan 治疗Diethylcarbamazine(hetrazan) is the first choice in treatment of filarial worm. A single-dose treatment of ivermectin plus Diethylcarbamazine has also proven highly effective, producing a 99 % reduction in the number of microfilariae
( 二 ) 防蚊灭蚊
( 三 ) 加强监测 Mass treatment coupled with the use of screens, insect repellents and insecticides has proven effective in the filarial control
Onchocerca volvulus
Onchocerciasis is considered by WHO the world’s second leading infectious cause of human blindness
Adult worms are found in fibrous nodules called onchocercomas in the subcutaneous connective tissues and viscera of humans
Adult worms may cause minor pathological alterations
When microfilariae invade the cornea, cause inflammation of the sclera, cornea, iris and retina, lead to impaired vision or the total blindness known as “ river blindness”
The presence of microfilariae in the connective of the skin, produces severe dermatitis
Worldwide, there are estimated to be 20 million (20000000) cases of onchocerciasis, approximately 96 % of the cases are in tropical Africa
Microscopically demonostration of microfilariae in dermal lymph of skin biopsyis proof of infection, or identification of adults in skin nodules
Ivemectin, administered in a single dose, the most effective treatment, Diethylcarbamazine(hetrazan) also, however, the drug does not affect adult worms------surgical
Loa loa
Loasis is limited to the African
The parasite usually cause no serious damage to the host
Adult worm in subcutaeous tissue, in eye, Calabar swelling
Microfilariae can be seen in unstained fresh prepared blood
Diethylcarbamazine(hetrazan) is the first choice in treatment of filarial worm.
Trichinella spiralis
旋毛虫 (Trichinella spiralis) 成虫寄生在小肠下部的肠壁,
幼虫寄生在人体横纹肌中,引起旋毛虫病 (Trichinellosis) ,
为人兽共患病。
食源性寄生虫病,特点:地区性、群体性、食源性、季节性
Trichinellosis is the disease among human and animal, a zoonosis.
The infection is endemic in many areas of the world where raw or undercooked meat, mainly pork is consumed.
形态 Morphology
成虫 Adult small & slender male: 1.5 mm X 0.04 mm female: 3.5 mm X 0.06 mm deposited larva
幼虫 Larva enveloped, 0.25-0.5 mm X 0.21-0.42 mm
生活史 Life cycle
成虫和幼虫均寄生在同一宿主体内
完成生活史需更换宿主
Human infection results from consumption of meat, most communly poorly cooked pork, containing encapsulated larva.
Life Cycle of Trichinella spiralis
交配4-6d
肠淋巴管或静脉 心 肺 全身各处
( 囊包 )
食入
脱囊
幼虫2-3days
成虫 幼虫 幼虫
4-6 days lymphatic vessels heart lung spread
Adult Larva Larva
another 2-3 days
LarvaLarvae can survive only in the skeltal muscle & become encysted in 2 to 3 weeks
致病 Pathogenicity
Trichinellosis, mainly result from larval invasio of muscle & othertissues and the hperimmune reaction of the host to the metabolic by-products and secretions of the larvae
1. 侵入期 肠道症状Invasion stage: due to penetration of adult female & larva into the mucosa & submucosa, begins 24 hrsafter infection and lasts for 1 to 7 days asymptomatic or transient gastrointestipational complaints
2. 幼虫移行期 全身症状、肌肉症状等一系列严重症状
Migration stage: begins about 1 week after infection and lasts after female worm die(4-6 wks) triad of myalgia palpebral edema eosinophilia fever
3. 成囊期Encystment stage:
诊断 Laboratory diagnosis
病原诊断 组织活检
免疫诊断
皮内试验、环蚴沉淀试验、皂土絮状试验、 ELISA 。
最近也将检测急性期的循环抗原作为手段之一。
•A parasitologic diagnosis is made by means of biopsy or at autopsy
•Serologic tests EIA dot immunobinding to detect circulating parasitic antigen
流行和防治 Epidemiology, treatment, prevention
主要预防措施:不食生肉
mebendazole 对成、幼虫均有效
This infection is much less common in Africa and Asia than in Europe and America.
The drug of choice is Mebendazole, which can kill both the larva and adult worms. ( albendazole is also effective)
No raw or undercooked meat