人体寄生虫学课件：Paragonimus westermani (卫氏并殖吸虫）

1、患者男性，37岁，因“低热，干咳伴胸痛2周，加剧3天”入院。近二周来出现刺激性咳嗽，夜间较剧，初为干咳，以后有咳痰，量不多，每日约3050毫升，痰为铁锈色且带腥味，伴轻度胸痛。摄胸片显示“右侧中下肺野见密度不均匀、边界模糊的圆形浸润阴影，双侧胸腔少量积液”。入院查体：神清，体温37.6，右下肺呼吸音略低，左下肺可闻及少量湿啰音。心率84次分，齐有力。腹平软，右上腹压痛，无反跳痛，肝脾肋下未扪及。双下肢无浮肿。患者入院诊断为肺部感染。给予抗炎治疗，当天体温有所下降。同时查外周血象示WBC22.6109L，N25%，E50%.治疗一周后症状与体征仍未缓解，复查血象示：WBC 16.3109L，E6

2、0%。因发现其E明显增高，故查患者痰液，直接涂片找到典型的肺吸虫卵。追问病史患者入院前二个月与朋友曾生吃大量醉蟹，最后确诊为肺吸虫病。故予吡喹酮4片tid 治疗三天。两周后患者症状、体征明显好转出院，另与其共食的朋友也因发热待查住入他院，临床表现及体征与其类似，最后也确诊为肺吸虫病。 These worms reproductive organs stand side by side. Adult worms usually live in the lungs of man and carnivores causing paragonimiasis, so they are also call

3、ed lung flukes. The paragonimiasis is a zoonosis. In china, there are two species of lung flukes of medical importance: Paragonimus westermani (卫氏并殖吸虫）, Paragonimus skrjabini (斯氏狸殖吸虫). Paragonimus westermani (卫氏并殖吸虫） This worm was first found in a tigers lung in India in 1877. It is the main kind of

4、 lung flukes infecting man. I. morphology 1. Adult: The body is elliptic, dorsally it is convex, ventrally it is flattened, reddish-brown in color, about 7.5-124-6mm ( length: width=2:1). It looks like half a peanut from side view. The sizes of two suckers are sub-equal. An oral sucker is situated a

5、nteriorly and a ventral sucker located in the central position of the body. Two testes, the ovary and the uterus are situated side by side. The vitellaria are well developed. The excretory bladder extends forward to the level of pharynx. The digestive tract is divided into two ceca. Schematic diagra

6、m Adult of Paragonimus westermani A adult of Paragonimus westermaniA adult of P. westermani 2. Egg is irregularly elliptic, golden yellow in color, 80-11048-60 in size. The shell is uneven in thickness. The thick and asymmetric shell with a distinct operculum encloses an ovum surrounded by more than

7、 10 yolk cells. eggsEgg of P. westermaniEgg of P. westermaniEgg of P. westermaniII. Life cycle 1. Infective stage: metacercaria 2. Infective route: by mouth 3. Site of inhabitation: lungs 4. Intermediate hosts: 1st int. host is melania snail(川卷螺). 2nd int. hosts are crab and crayfish. 5. Reservoir h

8、osts: carnivores such as tiger, lion, wolf, fox, dog, leopard, cat and so on. 6. Life span: 5-6 years Melania sailsCrayfish and crabCrayfish and crab小龙虾 蝲蛄 蝲蛄（东北黑鳌虾）和小龙虾（克氏原鳌虾）是不同的动物，蝲蛄是中国东北原产的，小龙虾原产地在北美，经日本进入中国。 蝲蛄对水质要求极高，生活在东北的山间河流里，被污染的水中不能存活。 小龙虾则在南方的河沟等水里，对水质要求不高。活体蝲蛄是青褐色，活体小龙虾是偏红色的。蝲蛄的鳌和背部表面比较

9、光滑，小龙虾的则有凹凸斑点。蝲蛄的个体要比小龙虾小很多。蝲蛄 小龙虾 penetrate the diaphragm layadolescents adults in lungs eggs penetrate Migrate to the lungs intestinal wallAdolescents excystation DischargedDuodenum In Human Body in sputum man eats raw crab or or in feces crayfish with metacercaria_metacercariae Eggs get into wate

10、r invade crab In Water 25-28 and crayfish 3-4weeks Miracidia hatch invadesCercariae Melania snail Escape asexual reproductionCercariae Daughter rediae Mother rediae SporocystsIII. Pathology and Symptomatology Adults inhabit lungs, although other organs are also involved. 1. Pathological lesions may

11、be classified into 4 stages: (1) Invading and migrating stage (侵入移行期): After excystation the adolescents penetrate the intestinal wall and migrate between organs in abdominal cavity for 1-3 weeks, then penetrate diaphragm to the lungs. (2) Suppurative stage (脓肿期). The bleeding and infiltration of ne

12、utrophils and eosinophils surrounding worms form a capsule, abscess. (3) Cystic stage (囊肿期), the cyst wall is formed due to the progressive fibrosis of the surrounding tissue. The cystic contents are chocolate or rusty thick fluid with eggs and Charcot-Leyden crystals(夏科-雷登氏晶体）, which looks like ses

13、ame paste. The shadow of the cyst can be seen on X-ray. Patients cough out the rusty sputum when the cyst communicates with the bronchioles. (4) Fibrous-scar stage (纤维瘢痕期), the worms are dead or escape from the cyst. The exudate and pus are expelled or absorbed and replaced by fibrous-scar tissue. C

14、harcot-Leyden crystalsCharcot-Leyden crystals(夏科-雷登氏晶体）Adults of Paragonimus westermani in lungsAdults of Paragonimus westermani in lungsAdults of Paragonimus westermani in lungs2. Clinical manifestations: Paragonimiasis may be classified into 4 types : (1) Pulmonary type: the symptoms resemble pulm

15、onary tuberculosis(结核)with low fever, loss of appetite (anorexia), night sweating, chest pain, cough, loss of weight and rusty sputum. (2) Abdominal type: abdominal pain，diarrhea or dysentery with blood, mucus and ova in feces. (3) Subcutaneous type: the wandering and painless subcutaneous nodules.

16、(4) Brain type: manifests epilepsy(癫痫), hemiplegia(偏瘫), monoplegia(单瘫), aphasia(失语), visual disturbance and resembles cerebral cysticercosis(脑囊虫病).IV. Diagnosis 1. Sputum examination: (1) Alkali digestive method (10%NaOH), (2) Direct sputum smear 2. Stool examination: (1) Alkali digestion , (2) Wate

17、r sedimentation method, (3) Direct fecal smear 3. Biopsy for Subcutaneous type 4. X-ray for Pulmonary type, CT for brain type 5. Immunological tests for reference.V. Treatment and Prevention 1.Treatment: Drug of choice is praziquantel. Other effective drugs include hexachloroparaxylol (六氯对二甲苯或血防846）, bithionol (bitin 硫双二氯酚或别丁). 2. Prevention: (1) Health education, (2) Avoid eating raw fresh water crabs and crayfishes. (3