Lecture Notes in Medical Technology: Lecture #9: THE INTESTINAL FLUKES

****** FASCIOLOPSIS BUSKI ******

Common name: Giant intestinal fluke

Disease: Fasciolopsiasis, Fasciolopsis edema

Morphology:

1. Adult is large, fleshy or broadly ovate or more often appears as elongatedly ovoidal, measuring from 20 – 75mm. The integument is spinose and there no cephalic cone. The oral sucker is about 0.5 mm and the ventral sucker is 2–3 mm. The intestinal ceca are unbranched and have characteristic indentations. It has a pair of highly dendritic testes which are found one after the other in the posterior half of the fluke. The branched ovary lies to the right of the midline & opposite it is the coiled uterus.

2. Ova is almost identical with those of the ova of F. hepatica. They measure from 130–150u x 80–85u. They are operculated & unembryonated when laid. The yolk granules are evenly distributed throughout the egg. In F. hepatica, there is clumping of yolk granules.

1^st Intermediate Host: Segmentina

2^nd Intermediate Host: Trapa natans, Trapa bicornis,

Eleocharis tuberosa (water chestnut)

Life cycle

****** ECHINOSTOMA ILOCANUM ******

Common name: Garrison’s Fluke

Synonyms: Fascioletta ilocanum, Euparydium ilocanum

Morphology:

1. Adult measures 2.5–6.5mm. It is attenuated posteriorly and the anterior portion is provided with a circumoral disc surrounded by spines which is diagnostic of this parasite. The oral sucker is situated at the center of the oral disc and the ventral sucker is located at the anterior 5^th of the body. The integument is surrounded by plaque–like scales; the testes is deeply lobed and lie one behind the other in the 3^rd fourth of the body with the lobed ovary situated in front of the anterior testes. The vitellaria are medium–sized follicles situated in lateral fields. The uterine coils fill the intercecal field between the anterior testes and the ventral sucker.

2. Ova is straw–colored, operculated and immature when laid, measuring about 83–116u. They are broadly ovoidal in shape with the presence of a distinct germ ball.

1^st Intermediate Host: Gyraulus convexiusculus (planorbid snail)

2^nd Intermediate Host: Pila conica or Pila luzonica

Life cycle

THE HETEROPHYIDS GROUP OF INTESTINAL FLUKES

General characteristics

1. Smallest but considered as the deadliest of all trematodes

2. Pyriform in shape measuring from 1–2 mm.

3. Rounded posteriorly and attenuated anteriorly with their cuticle surrounded by fine scale–like spines.

4. Provided with oral, ventral and genital suckers.

5. With gonotyl surrounding lip of the genital sucker which is surrounded by spines.

6. They are endemic in the Philippines.

7. Diagnosis is based on the recovery of eggs in stool

****** HETEROPHYES HETEROPHYES ******

Common name: Heterophyiasis

Morphology:

1. Adult measures from 1–2 mm, pyriform in shape and inhabit the small intestine of man and fish eating mammals. The oral sucker is small, the ventral sucker is about 3x the size of the oral sucker, thick walled and muscular and is situated in the anterior 3^rd of the body, the genital sucker is situated at the left posterior border of the ventral sucker and is provided with multidigitate spines. They have 2 oval testes arranged obliquely at the sub–caudal region, small oval ovary lies at the anterior portion of the posterior 3^rd of the body. There are 14 large polygonal vitelline follicles at the lateral portions of the worms.

2. Ova measures 28–30u, ovoidal, operculated and embryonated when laid. Hatching takes place only upon ingestion of the ova by the intermediate host.

1^st Intermediate Host: Pironella, Crithidia

2^nd Intermediate Host: Freshwater fish, mullet and tilapia

Life cycle

****** METAGONIMUS YOKOGAWAI ******

Common name: Yokogawai’s fluke

Disease: Metagonimiasis

Morphology:

1. Adult characteristic is almost similar to H. heterophyes except for the fusion of the ventrogenital suckers and deflected towards on side of the body; a pair of testes, one bigger than the other.