45 Schistosomiasis

Joe Jarvis 21/09/18

This is a flatworm/fluke/trematodes (different)

  • S. haematobium
  • mansoni
  • japonicum
  • intercalatum
  • mekongi

Haematobium vs everything else, urine vs gut/hepatic

45.0.1 Life Cycle

Insert life cycle

Depending on type, adults either go to venous plexus around bladder or gut.

45.0.2 Epi

200 million case world wide

115 million in urine. 80 million mansoni. rest else

Primarily african disease, some sout east asia and middle east and south america

Age distribution is not even. Primarily active disease in v young. Less so in adulthood.

Children are being v heavily exposed. In and out of water all the time. So heavy worm burden

45.0.3 Pathogenesis

Snails: LEARN SNAIL TYPES

Cercariae come out of snail

45.0.4 Clinical features

45.0.4.1 ALL SCHISTO

First thing you get is a rash called “swimmers itch”. Few hours to days after being exposed. Can also happen with avian schisto (can cause itch but not schistosomiasis)

Then in skin become schistosomulum, then off to lungs, then off to liver into portal vein

Then they start laying eggs, that’s when you get katayama fever.

  • Fever
  • Urticaria
  • Cough
  • Wheeze
  • Eosinophilia

This is an immunological reaction to eggs. A self limiting illness.

45.0.4.2 HAEMOTOBIUM

These worms go to perivesical venous plexis. Eggs go through bladder wall and out in urine.

Disease is due to the eggs and the immune response to them.

You will get haematuria

Eventually you can get ureteric obstruction (as scarred ureters). You can get bladder wall calcification.

What about eggs that stay in the bladder:

  • Granulomas
  • Calcified bladder
  • Bladder Cancer (you get squamous cell, rather than transitional cell)
  • Hydroureter
  • Hydronephrosis

You can also get eggs on uterine cervix, vagina, vulva

Men can get it on seminal vesicles, prostate.

Women with genital schisto, have 3x increased risk of having HIV. They’ve inflammation at cervix, making it easier for virus to get across.

45.0.4.3 MANSONI

These worms go to the venous plexus of the gut. The eggs here get embolised in the portal circulation. This causes inflammation in peri-portal spaces, causing peroportal fibroses.

“Symmers pipestem” periportal fibrosis

Cause horrendous portal hypertension.

The liver tissue itself is relatively unaffected. Slightly less risk of bleeding, but you still get loads of oesophageal varices.

Eggs can also cause minor haemorrhage in bowel mucosa. You can get a colitis in the colon. But no increased risk of cancer

Eggs can cause portal hypertension with all its complications.

There is also an association between gut schistosoma and HIV infection.

45.0.4.4 ECTOPIC Schistosomiasis

Eggs embolise to pulmonary arterioles. Cause cor pulmonale.

Also to cntral nervous system, or spine (can cause transverse myelitis)

THink of schisto in transverse myelitis and the issues go away.

45.0.5 Diagnosis

Find the parasite eggs in either urine or stool. (45% sens)

Serological assays (ELISA 96% sens for mansoni, 92% haematobium). But no use for early or acute infection as it takes 6 weeks to seroconvert

Eosinphilia in acute infection

Radiological tests

45.0.5.1 Case Definitions

TAKE WHO CASE DEFINITIONS FROM SLIDE

45.0.5.2 Eggs

Spine - Terminal Spine

Mansoni - Lateral Spine

Japonicum - Curved Spine

45.0.6 Treatment

Praziquantel 40-60mg/kg as a single dose orally

Active against all schistosome species. But only against adult forms. You need to wait at least 6 weeks!

After treatment 70-100% of patients cease to excrete eggs. 95% reduction in egg load

45.0.6.1 Katayama fever

  • Steroids for inflammation
  • Some praziquantel
  • Retreat again in 6 weeks for adult worms

45.0.6.2 Asymptomatic infection

  • Praziquantel (If exposure within 3 months, retreat after 6 weeks)

45.0.6.3 Symptomatic infection

Still praziquantel

45.0.7 Neruoschistosomiasis

3 day praziquantel course under steroid cover

45.0.8 Prevent/Control

  • Kill Snails
  • Clean Water Supply
  • Better Toilets
  • Treat Infected