Intestinal Infections by Trematodes

Question 1

What is the disease caused by Heterophyes heterophyes?

Answer 1

Heterophyiasis

Question 2

Morphology of Heterophyes heterophyes

Answer 2

1. Adult :
   * This is the smallest trematode parasite of man
   * Pear shaped or may take different shapes.
   * In addition to oral and ventral suckers it also possess a genital sucker
2. Eggs :
   * Operculated and emberyonated (contain a fully developed miracidium)

Question 3

What is the definite host in Heterophyes heterophyes

Answer 3

1. Man

2. Fish eating animals

Question 4

First intermediate host in Heterophyes heterophyes

Answer 4

Snails of the genera Pironella

Question 5

Second intermediate host in Heterophyes heterophyes

Answer 5

• Fishes, such as the mullet and tilapia (Bolty & boury)

* Infective stage: encycted metacercaria in fishes

Question 6

Mode of transmission in the 2nd intermediate host

Answer 6

eating undercooked or freshly salted containing encysted metacercaria

Question 7

Clinical findings of Heterophyes heterophyes

Answer 7

1. Colicky pain and diarrhea

2. Egg emboli

Question 8

Explain what is the egg emboli

Answer 8

Eggs may find their way through the genital sucker and are carried in

the lymphatic and portal circulation to ectopic extra-intestinal sites

such as the brain, spinal cord and myocardium

Question 9

Laboratory diagnosis of H. heterophyes

Answer 9

Detection of the minute operculated eggs in faeces

Question 10

Morphology of Schistosoma mansoni

Answer 10

• Adult worm lives in the inferior mesenteric vein plexus

1. Adult form:
   * have their integuments studded with prominent coarse tubercles (to differentiate from Schistosoma haematobium)
2. Gravid female :
   * uterus contains very few eggs, usually 1–3 only
3. Oral and ventral suckers are prominent in males and rudimentary in females
4. Male carries the female inside gynecophoric canal
5. Eggs :
   * non operculated and yellowish brown
   * have the characteristic lateral spine more near to the rounded posterior end

Question 11

Name the disease caused by Schistosoma mansoni

Answer 11

Intestinal schistosomiasis (Intestinal bilharziasis)

Question 12

Who is the definite host in Schistosoma mansoni?

Answer 12

Humans are the only natural definitive hosts

Question 13

Who is the intermediate host in Schistosoma mansoni?

Answer 13

Fresh water snails of the genus Biomphalaria

Question 14

Mode of transmission in S.mansoni

Answer 14

1. cercaria skin penetration during water use (swimming washing, …)
2. Humans :
   a. schistosomulae mature in the liver

b. the adult worms move against the blood stream into the venules of the inferior mesenteric group in the sigmoidorectal area
c. Eggs : penetrate the gut wall, reach the colonic lumen, and are shed in feces

Question 15

Clinical manifestations of S.mansoni

Answer 15

1. Cercarial dermatitis
2. Katayama fever
3. Intestinal bilharziasis
4. eggs deposited in the gut wall
5. Ectopic lesions
6. Portal hypertension

Question 16

The pathogenicity of Cercarial dermatitis

Answer 16

Following skin penetration by cercariae, a pruritic rash may develop locally. It is self-limiting

Question 17

Pathogenicity of Katayama fever

Answer 17

• after 4-8 weeks of cercarial invasion a serum sickness like illness may happen during production of eggs by females.
• It results from egg antigen stimuli, which leads to formation of immune complexes.
• Sign and symptoms include :
• fever
• rash
• arthralgia
• lymphadenopathy
• hepatosplenomegaly
• eosinophilia

Question 18

What happens when eggs deposits in the gut due to S.mansoni ?

Answer 18

cause inflammatory reactions leading to microabscesses, egg granulomas, hyperplasia, and eventual fibrosis

Question 19

Pathogenesis of Intestinal bilharziasis

Answer 19

During the stage of egg deposition in the large intestine:

• the patients develop pain in abdomen and bloody dysentery, which may go on intermittently for many years

Question 20

In s.mansoni ; Portal hypertension may cause________

Answer 20

gastrointestinal hemorrhages

Question 21

Ecoptic lesionnin S.mansoni

Answer 21

Include :

• hepatosplenomegaly
• periportal fibrosis
• portal hypertension as some of the eggs are carried through portal circulation into liver.

Question 22

What is the result of stool microscopic examination in s.mansoni ?

Answer 22

Eggs with lateral spines may be demonstrated microscopically in stools

Question 23

What is seen in rectal biopsy of S.mansonim?

Answer 23

Proctoscopic biopsy of rectal mucosa may reveal eggs

Question 24

What is the imaging test result of S.mansoni?

Answer 24

Ultrasonography is useful to detect hepatosplenomegaly and periportal fibrosis

Question 25

What does the blood examination reveal about S.mansoni ?

Answer 25

May reveal eosinophilia

Question 26

Morphology of Schistosoma Japonicum

Answer 26

Morphologically, they are similar to the schistosomes described above except:

1. The adult male is slender and does not have tubercles
2. The gravid female, pass up to 3,500 eggs daily
3. The eggs are smaller, more spherical, no spines but a lateral small rudimentary knob

Question 27

S.Japonicum is also known as________

Answer 27

Oriental blood fluke

Question 28

Where is the adult worm of S.japonicum found ?

Answer 28

seen typically in superior mesenteric vein plexus draining the ileocecal region

Question 29

Who is the definite host of S.japonicum ?

Answer 29

Man is the definitive host

• but in endemic areas, several domestic animals and rodents act as reservoirs of infection

Question 30

Who is the intermediate host of S.japonicum ?

Answer 30

Amphibian snails of the genus Oncomelania

Question 31

Where do eggs deposit in S.japonicum ?

Answer 31

superior mesenteric venules

Question 32

How the eggs deposit in S.japonicum ?

Answer 32

They penetrate the gut wall and are passed in feces at the superior mesenteric venules

Question 33

Another name/s of the disease caused by S.japonicum

Answer 33

oriental schistosomiasis or Katayama disease

Question 34

Pathogenesis of Katyama fever

Answer 34

• similar to that in other schistosomiasis, but probably because of the :
• higher egg output ——> Katyama fever manifests more severe

Question 35

Laboratory diagnosis of S.japonicum

Answer 35

• Eggs demonstrated microscopically in stools are with lateral knob
• Similar to that of S. mansoni