Presented by

ABID HUSSAIN

Abdul Wasey

Metagonimus is a genus of family Heterophyidae.

Cause disease Metagonimiasis.

Metagonimiasis was discovered by Katsurasa in 1911-1913 when he first observed eggs of M. yokagawai in feces .

M. takahashii was described later first by Suzuki in 1930

M. Miyatai was describe in 1984 by Saito

All three species are hermaphrodite.

Smallest intestinal fluke

ClassificationKingdom Animalia

Phylum Platyhelminthes

Class Trematoda

Order Opisthorchiida

Family Heterophyidae

Genus Metagonimus

species Metagonimus yokogawai

Metagonimiasis infections are endemic or

potentially endemic in following countries

including

Japan, Korea, China, Taiwan, the Balkans,

Spain, Indonesia, the Philippines , Russia,

India and Pakistan

Metagonimus yokagawai also called

the Japanese fluke

Metagonimus Takahashii

Metagonimus miyatai

Transmission requires two intermediate hosts,

The first of which is snails, most commonly of

species Thiara granifera.

Infection is acquired through the secondary

intermediate host, fish, that haven’t been

thoroughly cooked. Metacercariae encyst under

the scales or in the flesh of fish

Definitive hosts include humans and various fish-

eating mammals, primarily dogs, cats, and pigs.

Fish-eating birds may also be infected with

metagonimiasis

Eggs are very small. Eggs have a

smooth, hard shell that is transparent and

yellow-brown in color, ovoid egg shape.

They are about 26-28 μm length and 15-

17μm width.

The egg also has a very slight opercular

shoulder

leaf-shaped.

It is one of the smallest intestinal flukes, its ventral sucker is deflected to the right of its midline and is closely associated with the opening of the genital pore.

The testes are large and diagonal to each other

Ovary is anterior to the testes and the uterus is filled with eggs. The uterus is the largest organ in the body.

The size of the adult fluke is 2.5 mm length by .75 mm width.

oral sucker (OS), pharynx (PH), intestine

(IN), genitoacetabulum (GA), ovary

(OV), the large, paired testes (TE), and

eggs within the uterus (EG).

Life cycleAdults release fully embryonated eggs each with a fully-developed miracidium, and eggs are passed in the host’s feces

After ingestion by a suitable snail (first intermediate host), the eggs hatch and release miracidia which penetrate the snail’s intestine

The miracidia undergo several developmental stages in the snail, i.e. sporocysts , rediae , and cercariae. Many cercariae are produced from each rediae. The cercariae are released from the snail

It is encyst as Metacercariae in the tissues of fish (second intermediate host)

The definitive host becomes infected by ingesting undercooked or salted fish containing Metacercariae

After ingestion, the Metacercariae excyst, attach to the mucosa of the small intestine and mature into adults

Pathogenesis

It cause Metagonimiasis

Site of infection is small intestine

The incubation period is around 14 days

Infestation may persist for more than one

year

Sign and Symptoms

Diarrhea

Abdominal pain

Nausea

lethargy

anorexia

Fatigue

malaise

seizures, neurologic deficits

Diagnosis

Fecal test

Serological test(Elisa)

Avoid eating uncooked food in endemic area

Prevent fecal contamination of fish ponds.

Education regarding method of transmission

Snail control

Avoid feeding raw fish to cats and dogs in endemic area.

Praziquantel(drug of choice)

Tetrachloroethylene

bithionol

Niclosamide

Nicoflan