ParagonimiasisParagonimiasis

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

EtiologyEtiology

Morphology

Adult worm: they are monoecious, the reproductive organs are parallel, have two suckers

Eggs: golden brown, ovate, operculate, the size is 80-120×48-60m

Metacercariae: round or ovate. Diameter 300-400 m, 1-3 layers of cyst wall

Life Cycle

Man with adult worm to mature passing eggs into water2-3months 21 dayseating 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 1st and 2nd

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 Pathogenesis and Pathogenand 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 cra

nial cavity, invade into the brain Invade into greater psoas muscle Migrate through intervertabral foramen int

o 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 lu

ng, 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 mod

erate infections are asymptoms In severe infection, the clinical manifestati

ons are complex

Clinical Manifestations Systemic symptoms: chills, slight fever, weaknes

s, 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 p

aragonimus westermani and pagumogonimus skjabin are on page 227 of our textbook

Laboratory Findings

General examination: in blood routine test, WBC raise to 10-40 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 cray

fish 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

TreatmentTreatment

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 age

nt 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: