TREMATODES Helminthes

In general:  They are flat worms  Provided with suckers as organs of attachment  Usually as leaf shape  Commonly known as Flukes  No body cavity  Male and Female systems are together with Schistosomes as an exception.

1- Liver Fluke (Fasciola):  Adult: with shoulders  Egg: oval in shape and it’s operculated, it’s immature.  Hosts: Man : definitive host, Snail: first intermediate host, Vegetations: second intermediate host.  Habitat: bile duct.  Infective stage: Encysted Metacercaria.  Complication: bile duct obstruction (Jaundice).

Diagnosis:  High eosinophilia  Stool examination: egg in stool  Serology  CT scan or Ultrasound.

We have to differentiate between true fascioliasis and false fascioliasis  The two conditions release eggs of Fasciola.  False Fasciola: results from eating infected liver of animals as Fasciola may affect sheep, buffalo. In this condition, the patient release eggs in the stool, but without infection with fasciola.  To differentiate between true and false Fasciola: we forbid the patient from eating animal liver for three days, then we repeat stool examination. If eggs disappear, it is false fascioliasis, but if eggs still present in the stool, it is true fascioliasis.

2- Fasiolopsis buski (Intestinal Fluke):  Adult without shoulders.  Habitat: small intestine.  Egg: oval in shape with small operculum, immature.  Infective stage: Encysted Metacercaria  Hosts: Man: Definitive host, Snail: first Intermediate host, Chest nut: second intermediate host.  Complication: may lead to intestinal obstruction in the case of presence of large number of worms.

Diagnosis:  Stool Examination: egg in stool  Serology

3- Paragonimus (Lung Fluke):  Adult: oval in shape with 2 suckers.  Egg: small, oval, operculated, immature.  Infective stage: Encysted Metacercaria  Hosts: Man: Definitive host, Snail: first intermediate host, Crap fish: second intermediate host.  Can lead to Pneumonia and lung abscesses.

Diagnosis:  Sputum Examination.  Stool examination in some cases (specially in children) when swallowed.

4- Schistosoma (Blood Fluke):  Have 3 species can be easily differentiated by their egg shape.  Adult: differs from other trematodes in being separate sex.  Eggs for all species are mature.  A- Haematobium:  Habitat: blood vessels around the UB.  Egg: Yellowish, mature with terminal spine.  Diagnosed by Urine examination.

 B- Mansoni:  Habitat: Inferior vein of large intestine  Egg: large, yellowish with lateral spine  Diagnosed by : stool examination.  C- Japonicum:  Habitat: Superior veins in small intestine  Egg: small, rounded with small lateral spine.  Diagnosed by: stool examination.

Mansoni

Japonicum

S. Japonicum is the most dangerous species:  It is serious. Starts by katayama fever which is manifested by fever, hepatosplenomegaly and lymphadenopathy.  Severe complications are in the form of cerebral and spinal cord affection leading to epilepsy and hemiplegia.