1. Paragonimiasis

2. Introduction
A kind of chronic disease caused by paragonimus westermani.
Adult worm of paragonimus westermani inhabit lungs of the final host, causing cough, chest pain, rusty sputum and hemoptysis
Infected by eating raw crayfish and freshwater crab

3. Morphology
Adult worm: they are monoecious, the reproductive organs are parallel, have two suckers
Eggs: golden brown, ovate, operculate, the size is ×48-60m
Metacercariae: round or ovate. Diameter m, 1-3 layers of cyst wall

5. Life Cycle
Man with adult worm to mature passing eggs into water 2-3months 21 days eating miracidi Metacercaria first intermediate host(special snail) second intermediate host 3 months (crayfish and freshwater crab) cercaria

7. Epidemiology
Source of infection: humans mammals which can produce eggs
Route of transmission:
1.The presence of the final host:patients and the infected mammals
2.The presence of a large amount of 1st and 2nd intermediate host
3.The habit of eating the freshwater crayfish and crab
Susceptibility: every one is susceptive

8. Pathogenesis

9. Juvenile Worms
Metacercariae excyst in duodenum, and into abdominal cavity, the migrate cause mechanical lesions
Penetrate diaphragms into pleural cavity to cause lung cyst
The pathological change caused by pagumogonimus include :subcutaneous nodules mass, exudative pleurisy , liver lesion, and eosinophilia. The typical lesion are eosinophilous granulomas

10. Adult Worms Inhabit lungs
Migrate through lacerated foramen into cranial cavity, invade into the brain
Invade into greater psoas muscle
Migrate through intervertabral foramen into epidural cavity

11. Process Caused by Eggs
The reaction is slight

12. Basic Pathological Lesion
The process are divided into three stages:
Abscess stage: the worms migrate from intestine to lung, result in hemorrhage necrosis of the tissue, macrophages, eosinophils and neutrophile are aggregated causing eosinophilous abscess
Cyst stage:the worms provoke a granuloma reaction that gradually proceed to develop fibroid encapsulation
Fibrosis and scar stage:the internal material are excreted or absorbed, consequently proliferation of the fibrous tissues

13. Clinical Manifestations
Systemic symptoms: chills, slight fever, weakness, headache, chest pain, night sweat. Some patients have urticaria and asthma. Eosinophilia is common
Respiratory symptoms: the involvement of the lung are characterized by: rusty sputum, chest pain, coughing, hymoptysis, expectoration, hydrothorax, eggs can be found in the sputum
Abdominal symptoms: general abdominal pain, diarrhea, nausea, vomit, and hepatomegaly.asites, intestinal adherence and obstruction occur in severe infection

14. Clinical Manifestation
Nervous system symptoms: the symptoms are complicated due to the variation of the location of the worms:
Brain: Intracranial hypertension
Damage of the brain tissue
Abnormal stimulation of brain tissue:
Inflammation
Spine: dyscinesia and sensory disturbance below the ridden area of the spine

15. Clinical Manifestation
Subcutaneous nodules and masses: at any part of the body, mainly abdomen, chest and backside. Always migratory
Other symptoms:
Differentiation of manifestation between paragonimus westermani and pagumogonimus skjabin are on page 227 of our textbook

16. Laboratory Findings
General examination: in blood routine test, WBC raise to G/l, and more than 80% may be eosinophils. ESR fasten
Pathogen examination:
Sputum:eggs, eosinophils and Charcot-Leyden crystal may be found. The positive rate of finding eggs can reach 90%
Stool: the eggs come from sputum swallowed, the positive rate is 15-40%
Biopsy of subcutaneous nodules and masses: typical eosinophilous granuloma with eggs, larvae and adult worm

17. Laboratory Findings Immunological test: ELISA
Intracutaneous test
ELISA
Dot-ELISA and Weston blot
IHA and RIA etc.
X-ray
Chest examination: CT
Brain vascular and spine photography

18. Diagnosis Epidemiologic date:
history of eating raw or pickled freshwater crab or crayfish
Clinical manifestation:
cough, rusty sputum,
migratory subcutaneous nodules and masses
epilepsy, headache and paralysis
Laboratory findings:
Finding eggs or worms
Immunological test

19. Treatment
Praziquantel is the best choice of drug for the therapy of paragonimiasis
Dose:25mg/kg, three times a day, for 2-3 days, the brain type need 2 times therapy, the interval is 7 days
The other drugs for choice include: mebendazole:efficient for p.skijabini
bithionol

20. Prevention Control of the source of infection:
Treat the patients and domestic animal at the same time.
Health education
Avoid eating raw fresh water crabs and crayfishes.
Avoid sputum and stool getting into water.