Paragonimiasis

Intruduction  A kind of chronic disease caused by paragonimus westermani, paragonimus szechuanensis and several other related species  Adult worm of paragonimus westermani inhabit lungs of the final host, causing cough, chest pain, rusty sputum and hemoptysis  paragonimus szechuanensis cause subcutaneous nodules and masses  Infected by eating raw crayfish and freshwater crab

Etiology

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

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

Epidemiology  Source of infection: humans mammals and other worm carriers, 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 1 st and 2 nd intermediate host 3.The habit of eating the freshwater crayfish and crab  Susceptibility: every one is susceptive

Character of Epidemic  Widely distributed: Asia, Africa, America in our country, more than 21 provinces are involved in the infection  It mainly occurs in summer and autumn  North:the type of crayfish epidemic South:the type of freshwater crab epidemic

Pathogenesis and Pathogen

Process Caused by 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 skjabin include :subcutaneous nodules mass, exudative pleurisy, liver lesion, and eosinophilia. The typical lesion are eosinophilous granulomas

Process Caused by 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  All these causing space occupying lesion

Process Caused by Eggs  The reaction is slight

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

Clinical Manifestation  Incubation period: 3-6 months  The onset is insidious, most slight and moderate infections are asymptoms  In severe infection, the clinical manifestations are complex

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

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

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

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

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

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

Differential Diagnosis  Tuberculosis : tubercular pleurisy or peritonitis  Brain tumor and other brain parasitosis  Viral hepatitis

Prognosis  Because the species, the location and the degree of infection are different, the prognosis is difference.  The prognosis are usually good  The prognosis of cerebrospinal type is bad

Treatment

Pathogen 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

Heteropathy Treatment  Cough, chest pain: antitussive, analgestics  Epilepsy: valium or luminal  Intracranial hypertension: dehydrating agent  Space occupying lesion: surgery operation

Prevention  Control of the source of infection: Treat the patients and domestic animal at the same time.  Cut off the route of transmission: