The Lung Fluke

8/14/2019 The Lung Fluke

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The Lung FlukeParagonimus westermani

By:Glazelle D. Pago


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Common name: Oriental Lung fluke


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I. ParagonimusThese worms reproductive organs

stand side by side. Adult worms usually

live in the lungs of man and carnivores

causing paragonimiasis, so they arealso called lung flukes. It is essentially

a zoonosis.


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Paragonimus westermani

This worm was first found in a

tigers lung in India in 1877. It is the

main kind of lung flukes infecting

man.


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II Morphology of adult Paragonimuswestermani


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Morphology


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Morphology of the Egg

Paragonimus westermani eggs range from 80 to

118 by 48 microns. They are golden brown in color,with ovoid in shape, with a thick shell, and oftenasymmetrical with one end slightly flattened.

The thick and asymmetric shell with a distinct

operculum encloses an ovum surrounded by morethan 10 yolk cells.


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Egg of P.westermani


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Microcercouscercaria

It is covered of spines;ellipsoidal with small

tailHas a stylet at the dorsal side of theoralsucker 2nd larval stage developing from the

mirasidium inside the snail host( 1st

intermediate host:Antemalania asperata)and infects crustacean(mountain crab:Sundathelphusa philippina) as 2 nd intermediate host


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Metacercaria

Round and encysted larva

Infective stageMeasures from 381-457 um


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III.Life Cycle


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IV Pathology and Symptomalogy

Adults inhabit lungs, although other organs arealso involved.

1. Pathological lesions may be classified into 4stages: (1)Invading and migrating stage: Afterexcystation the adolescents penetrate theintestinal wall and migrate to the lungs.

(2) Suppurative stage. The bleeding and infiltrationof neutrophils and eosinophils surroundingworms form a capsule, abscess.


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(3) Cystic stage, 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, which looks likesesame 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, the worms are dead or escape from the cyst. The

exudate and pus are expelled or absorbed and replaced by fibrous-scar


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General symptoms

Symptoms are difficulty inbreathing, coughing, and bloody

sputum.


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V Diagnosis

Chest x-ray and finding a ringshallowed opacityDetection of the characteristics of eggs in sputum, or stool


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VI Treatment and Prevention

1.Treatment: Drug of choice is

praziquantel.Other effective drugs include

hexachloroparaxylol, bithionol (bitin).

2. Prevention:

Health education,

Avoid eating raw fresh water crabs and

crayfishes.


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VII Prevention And Control

Eating sufficiently cooked crab and meatSafe food preparation will help reduce theinfectivity of foodChange in dietary habits of the populationthrough health education and promotion


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VII Epideomology This disease is prevalent in Far East, Africa

and South America. There are endemic foci

in 22 provinces in Northeast, East and

Southwest of China. Its prevalence is

related to eating raw crabs and crayfishes

and the natural foci.

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The Lung Fluke