Trematodes of Medical

Importance

Zbigniew Pokora

Fasciola hepatica

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Eggs of Flukes

A. Opisthorchis felineus

(the cat liver fluke)

B. Clonorchis sinensis

(the Chinese liver fluke)

C. Paragonimus westermani

(the Oriental lung fluke)

D. Hetrophyes heterophyes

E. Dicrocoelium dendriticum

(the lancet fluke)

F. Fasciola heptica

(the sheep liver fluke)

G. Fasciolopsis buski

Liver Flukes

A. Opisthorchis felineus

(the cat liver fluke)

B. Dicrocoelium dendriticum

(the lancet fluke)

C. Fasciola hepatica

(the common sheep liver fluke)

D. Clonorchis sinensis

(the Chinese liver fluke)

Intestinal Flukes

In the upper line comparison of size is presented, in the lower one – more important morphological features

A. Fasciolopsis buski

B. Heterophyes heterophyes

C. Metagonimus yokogawai

D. Echinostoma ilocanum

Other Flukes Occasionally Parasitizing the Human Alimentary Tract

Trematode Geographic

distribution

Habitat of adult

worms

Mode of infection

Gastrodiscoides

hominis

India (Assam,

Bengal, Bihar,

Orissa), Vietnam,

the Philippines,

Kazakstan

large intestine

(caecum,

ascending colon)

?

(complete life

cycle is unknown)

Watsonius

watsoni*

Africa small intestine probably by

ingestion of

vegetation on

which

matacercariae have

encysted

Plagiorchis

philippinensis**

Southeast Asia the

Philippines)

small intestine probably by

ingestion of grubs

of certain insects

believed to be

second hosts of the

trematode

Spelotrema

brevicaecca

Southeast Asia

(the Philippines)

small intestine probably by

ingestion of

metacercariae

encysted in flesh

of crabs, being

second hosts of the

trematode

Dicrocoelium

dendriticum

cosmopolitan biliary passages ingestion of

metacercariae

encysted in ants

Troglotrema

salmincola

North America small and large

intestine

ingestion of

metacercariae

encysted in flesh

of infected fish

(salmon

poisoning)***

* Only once was found in human subject at the autopsy of an emaciated West

African Negro who died of a severe diarrhoea.

** Other fluke of this genus occurs in Java (P. javensis). It was obtained as a

single specimen at postmortem of a native Javanese who had harboured a heavy

infection of Echinostoma ilocanum.

*** The fluke per se is apparently not clinically important, but an associated

disease-producing agent, a rickettsia (Neorickettsia helmintheca) produces

severe, frequently fatal symptoms.

Medically Important Flukes of the Genus Paragonimus Parasite (etiologic factor

of disease)

Snails being main hosts

for parthenogenetic

generation of the

trematode

Geographic distribution

Paragonimus

heterotremus

Tricula gregoriana

(Prosobranchia:

Hydrobiidae)

Southeast Asia

Paragonimus

hueitungensis

Tricula cristella

(Prosobranchia:

Hydrobiidae)

China

Paragonimus miyazakii Bithynella spp.

(Prosobranchia:

Hydrobiidae)

Japan

Paragonimus skrjabini Assiminea lutea

(Prosobranchia:

Assimineidae),

Tricula gregoriana

(Prosobranchia:

Hydrobiidae)

China

Paragonimus westermani Semisulcospira libertina

(Prosobranchia:

Pleuroceridae),

Thiara spp., Brotia spp.

(Prosobranchia:

Thiaridae)

Southeast Asia

Paragonimus africanus Potadoma freethii

(Prosobranchia:

Pleuroceridae)

Paragonimus

uterobilateralis

?

Central Africa

Paragonimus

caliensis

Aroapyrgus colobiensis

(Prosobranchia:

Hydrobiidae)

Paragonimus

ecuadoriensis

?

South America

Paragonimus mexicanus Aroapyrgus costaricensis

(Prosobranchia:

Hydrobiidae)

Central and South

America

Paragonimus kellicotti Pomatiopsis lapidaria

(Prosobranchia:

Hydrobiidae)

North America