Heterophyes heterophyes is a small parasitic fluke that lives in the intestinal villi of humans. Its first intermediate hosts are snails found in Asia and the Middle East. Adults are 1-2 mm long with testes, an ovary, and spines covering their body. Eggs are yellow-brown, 27-30 by 15-17 micrometers. Infection is acquired by eating raw or undercooked fish containing the encysted metacercariae stage. Most people are asymptomatic but large infections can cause diarrhea, abdominal pain, and malnutrition. Diagnosis is by finding eggs in stool. Treatment is with praziquantel.

1. CASMER JUBELAG BSN 1-O

2. Heterophyes heterophyes is a small parasitic fluke. The adult parasite lives in the
intestinal villi of humans (the definitive host). The first intermediate host of
Heterophyes heterophyes are snails, Cerithidia species and Pironella species which
are found in Asia and the Middle East respectively.

3. Adults, Male & Female: It measures 1-2 mm in length. The testes are large
and paired, and are situated near a small ovary. The surface of the worm is
covered with minute spines. The body is covered by scales. Adults reside
in the small intestine of the definitive host.
The female fluke ovary is located near the end of the body.
Ova: The egg is ovoid, operculate, elongate and light brown (almost yellow)
in color. The egg contains the embryo (miracidium).
It measures 27 - 30µm by 15 – 17µm.

5. Finding eggs (colored yellow-brown
and measuring about 30 μm by 15
μm) in the feces.
Acquired by eating infected raw or undercooked
fish from freshwater or brackish water containing
metacercariae (encysted stage). After ingestion,
metacercariae excyst and attach to the mucosa
of the small intestine.

6. Heterophyiasis.
It is the infection with the intestinal fluke Heterophyes heterophyes,
which is acquired by eating infected raw or undercooked fish from
freshwater or brackish water. Mullets, gobies, perches, and Tilapia
are important fish intermediate hosts. Adult trematodes parasitize
the small intestine and cause mucosal inflammation.

7. Most people are asymptomatic but when large numbers
of flukes are present, the clinical picture is one of
intermittent diarrhea with mucus, abdominal tenderness,
and discomfort. Occasionally, the flukes penetrate the
intestinal wall and form granulomas in the peritoneal
cavity. Rarely eggs can gain access to the lymphatics
and then the blood stream, embolizing to cause
granulomatous lesions in brain, heart, lungs, spleen,
and liver, where they may incite serious disease.
Onset of symptoms is typically about 9
days after ingestion of contaminated fish
and can include anorexia, nausea,
abdominal pain, malabsorption, weight
loss, dyspepsia, and diarrhea.
Eosinophilia may be present.

8. The diagnosis is based on the
microscopic identification of eggs in the
stool. However, the eggs are
indistinguishable from those of
Heterophyes heterophyes and those of
Clonorchis and Opisthorchis.

9. Treatment consists of praziquantel, 75 mg/kg in
one day divided in three doses.
Prevention and Control:
Avoid eating raw or undercooked fish that may
contain these intestinal flukes.

10. Echinostoma species are a group of trematodes that
can be acquired by eating raw or undercooked
freshwater mollusks or fish infected with
metacercariae. The ingested metacercariae excyst in
the intestine, attach to the small intestinal mucosa,
and develop into adults.
Examples of Echinostoma species are the
following: Echinostoma hortense, Echinostoma
cinetorchis & Echinostoma revolutum

11. Adult, Male and Female: Adults of Echinostoma species are much longer than wide and measure about 2-
10 mm long by 1-2 mm wide, depending on the species. The oral sucker is surrounded by a collar of spines,
the number of which varies among species. The oral and ventral suckers are located fairly close to one
another. A single ovary is situated near the large, paired testes. Adults reside in the small intestine of the
definitive host.
Ova: It measures 80–135 µm long by 55–80 µm wide.
They have an inconspicuous operculum and the abopercular end is often thickened.

13. Presence of spines around the oral
sucker, forming a specific shape
known as collar spines. The number
and arrangement of these spines is
the basis of genus identification.
Acquired by eating raw or undercooked freshwater
mollusks or fish infected with metacercariae.
The ingested metacercariae excyst in the intestine,
attach to the small intestinal mucosa, and develop
into adults.

14. Echinostomiasis.
It is a food-borne infection caused by an
intestinal trematodes belonging to the
family Echinostomatidae.
They infect the gastrointestinal tract of
humans. Patients are usually
asymptomatic.

15. Echinostoma species produce no
symptoms in most people, but can cause
epigastric pain, abdominal cramps, and
diarrhea. However, with heavy infections,
the worms can produce catarrhal
inflammation with mild ulceration and the
patient may experience abdominal pain,
anorexia, nausea, vomiting, diarrhea and
weight loss.
Adults begin to produce and release many
self-fertilized eggs ten days after infecting the
definitive host. The eggs hatch in fresh water in
nine to twelve days. Exposure to light
stimulates hatching.

16. The diagnosis is based in finding of
eggs in wet mounts of stool. Eggs are
broadly-oval, unembryonated when
shed in stool, and have an
inconspicuous operculum.

17. In human infections, praziquantel is the drug of choice
for echinostomiasis. Mebendazole and albendazole
have also been shown to have an effect against
echinostomiasis.
Eating raw or improperly cooked freshwater fish and
fresh or brackish water snails should be avoided to
prevent echinostome metacercarial infections.

18. CASMER JUBELAG BSN 1-O