Pathogenesis And Clinical Aspects Of Tropical Infe
All documents for this subject (5)
Seller
Follow
jokestynen
Content preview
FOODBORNE HELMINTHS: FASCIOLA AND TAENIA SPP. (24/02)
INTRODUCTION
• Parasites = organisms that, in order to complete their natural life cycle, must live temporarily
or permanently in or on another living organism (the host), from which they derive nutrients
• Most human parasites belong to the protozoa (unicellular) or helminths (worms)
HELMINTHS AND THEIR LIFE CYCLE
• There are 4 main types but this lecture will mainly focus on Fasciola (fluke) and T. solium
(tapeworm)
• Helminths have complex life cycles: eggs, larvae, adult worms
• Definitive host: harbors adult stage; production of eggs or larvae that leave the host via
feces, urine, etc.
• Intermediate host/environment: development of infective larvae, with or without (asexual)
multiplication; infection of host, through skin or orally, etc.
FOODBORNE HELMINTHS
• Infection with foodborne helminths can happen through fish consumption, contaminated
plants, water, eating of wild meat, …
• Consumer: stage where people get infected
• It’s mainly zoonoses: animal as food source/contaminator of food source
o But also often an important environmental factor
, • One Health approach!: Is the idea that the health of people is connected to the health of
animals and our shared environment
FASCIOLA
INTRODUCTION
• Taxonomy: it belongs to the class of the Trematoda (flukes) and
the subclass of the digenea (flukes with an indirect life cycle)
• It’s a liver fluke
• Causes disease in humans: Fasciolosis
o Historically fasciolosis was considered an animal disease
• It was added to the list of neglected tropical diseases (NTD) by
WHO in 2010
• 2.6 million are affected and >180 million at risk
• It also has an economic impact on livestock sector
TRANSMISSION
LIFE CYCLE-DEVELOPMENTAL STAGES
• Cattle and sheep are definite host: when infected
they pass yellow eggs in the feces which are
unembryonated (a)
• For embryonation they need an aquatic
environment (b)
• Miracidium (which is inside the egg) will now hatch
from the egg and actively seek a snail (c)
• Miracidia are free-living in the water will actively
penetrate the snail
• Next: Sporocyst (d)→ redia (e)→ cercaria (f)
• Cercaria are released from the snail host in the
water and will seek vegetation where they encyst and transform into metacercaria (don’t
have a tail anymore)
• Humans can become infected as definitive host: they penetrate the intestinal wall and
migrate to the liver → in the liver parenchyma juvenile F. hepatica (first stage in final host)
can be found → adult flukes in bile duct
2
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller jokestynen. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $3.93. You're not tied to anything after your purchase.
