Schistosoma japonicum

Introduction

  • Schistosoma japonicum is found in China, Japan, the Philippines, and Indonesia. It causes disease of the bowel with the eggs being passed out in the feces.
  • It differs form S. mansoni and S. haematobium in that it is a zoonosis in which a large number of mammals serve as reservoir hosts; cats, dogs and cattle playing major roles in the transmission of the disease.
  • The life cycle is not very different from that of S. mansoni, the intermediate hosts are from the subspecies Oncomelania hupensis. Sexual maturity is reached in about four weeks and eggs may be seen in the feces as quickly as five weeks.
  • The worms live coupled together in the superior, mesenteric veins and deposit 1500–3500 eggs per day in the vessels of the intestinal wall. The eggs infiltrate through the tissues and are passed in the feces.

Morphology

  • The adult worms are longer and narrower than the S. mansoni worms. The ova are about 55-85μm by 40-60μm, oval with a minute lateral spine or knob.

Clinical Disease

  • The main lesions are again due to the eggs, occurring in the intestine and liver. The eggs which are sequesters in the intestine mucosa or submucosa initiate granulomatous reactions, resulting in the formation of pseudotubercles.

Schistosoma japonicum egg

Due to the number of eggs released by the females the infection is more severe than one with S. mansoni. This is also due to the parasite being less well adapted to man, therefore, the circumoval granuloma is very large. The initial illness can be prolonged and sometimes fatal.

Laboratory Diagnosis

Microscopy
Laboratory confirmation of S. japonicum infection can be made by finding the eggs in the feces after an iodine stained, formol-ether concentration method. When eggs cannot be found in the feces, a rectal biopsy can be examined.

 

Share This Post

Related Articles

Leave a Reply

You must be Logged in to post comment.

© 2021 Medical Laboratories. All rights reserved. Site Admin · Entries RSS · Comments RSS
Powered by WordPress · Powered by Medical Labs