FASCIOLOPSIS BUSKI

Fasciolopsis buski is known scientifically as thelargest intestinal fluke in humans.Infection occursprimarily in Asia and the Indian subcontinent,especially in area where humans raise pigs and consume freshwater plants, so this helminth is also named as “giant Asian intestinal fluke”.This giant parasite has even been described as “meat worm”

or “reddish worm” in traditional Chinese medical book.

Introduction

I. Morphology(1) Adult

• Long elliptic, flesh-colored, looks like

a slice of raw meat

• The size: 20-75×8-20×0.5-3mm

• The ventral sucker (filler-like

/ infundibular ) is larger and near by the

much smaller oral sucker

• Two coral-liked(珊瑚 ) testes are located

in the posterior half of the body

No seminal receptacle

ventral sucker is 3-4 times larger than oral sucker

uterus

cecum

vitellaria

oral sucker

ovary

testes

(2) Egg

The thinner shell with an operculum (not so obvious)

encloses an ovum and 20-40 yolk cells

Slightly yellow in color

130-140×80-85µm (the largest helminth egg)

Oval / long elliptic in shape

The first intermediate host： Segmentina

water caltropwater caltrop 水红菱水红菱 茭白 cane shoot

Water chestnut荸荠

Aquatic plant vectorThe second intermediate host：

II. Life cycle

1.Site of inhabitation: small intestine,

2. Infective stage: metacercaria,

3. Infective route and mode: eating raw water

plants with metacercariae,

4. Intermediate hosts: Planorbis snail,

5. Reservoir hosts: pig,

6. Life span: 1-4 years,

7. Egg output: 15,000/worm/day.

Adolescent Adult Eggs

Duodenum In Human Body 3 months are discharged

man eats metacercariae in feces

on raw water plants ────────────────────────────Metacercaria Eggs get into water encystations on the In Water 25-30℃ surface of water plants 2-3 months 3-4weeks

Miracidia hatch out invadesMany cercaria asexual reproduction Planorbis snail Many daughter rediae Many mother rediae Sporocysts

III. Pathology and Symptomatology

1.The enteritis due to worms’ adhesion

manifests abdominal discomfort and

diarrhea.

2. Malnutrition results from the worms

sharing food with the host and diarrhea.

IV. Diagnosis

Stool examination:

1. Direct fecal smear,

2. Water sedimentation method

V. Treatment and Prevention

1. The treatment of the patients, carriers and pigs

Drug of choice is praziquantel. Other effective

drugs include hexachloroparaxylene, bithionol (bitin).

The drug for pig is dipterex (敌百虫 ).

2. Prevention

(1) Health education

(2) Deal with night soil.

(3) Avoid feeding pigs on raw water plants

VI. EpidemiologyThis disease is prevalent in Southeast

Asia,China, Japan, Korea, Thailand, Burma, Kampuch

ea, Vietnam, Bangladesh, Philippines,Indonesia, Malay

a and India

. In China it is found in 18 provinces, city and

autonomic region except north and west regions.

The prevalence of fasciolopiasis is relative to grow

ing water plants and feeding pigs

on water plants.

Thank you !