Parasites

15 important questions on Parasites

What is the life cycle of echinococcosis granulosus?

The tapeworm cycles between dogs and sheeps. In sheeps the liver gets infected and in dogs the worm is present in the gut. It can eventually infect humans, when eggs are ingested (food/water/soil). The eggs are released via the dog's stool. Dogs can only be infected after eating sheep liver, which happens only in countries in wich sheeps and dogs live closely together.

What is the life cycle of echinococcosis multilocularis?

The tapeworm cycles between fox and mouse. In the fox the tapeworm is present in the gut and in the mouse the liver is infected. Humans can get infected after ingesting eggs that are released by the fox's stool.

What are negative effects of a helminth infection?

  • Susceptible to infections due to reduced immunity
  • Tumors, probably of reduced anti-tumor immunity
  • Reduced vaccine efficacy due to reduced immune response
  • Higher grades + faster learning
  • Never study anything twice
  • 100% sure, 100% understanding
Discover Study Smart

What are positive effects of a helminth infection?

  • Prevents allergies/asthma
  • Prevents auto-immune diseases
    • Reduced incidence of inflammatory bowel diseases

Which three types of parasites are there?

- helminths
- protozoa
- arthropods (exoskeleton, spider/tyke)

How is Schistosomaisis treated?

With praziquantel

What are CAA and CCA?

Circulating anodic antigen and circulating cathodic antigens. This are antigens secreted by the worms. They are degraded very quickly, so presence indicates an active infection.
After 4-6 weeks CAA and CCA can be detected

How is malaria treated?

With drugs that kill the parasite, some parasites are drug resistant.

Why is it difficult to design a vaccine against parasites?

- difficult life cycle
  • they develop quickly to other stages which makes it difficult to generate a proper immune response towards one life stage
- lack of complete understanding of the types of immune response needed for proper protection
- parasites are very good at evading the immune system

Why is it difficult to design a vaccine against hiv?

- HIV mutates rapidly
- no complete understanding of the immune response
- limited investments

Which type of immune response is provoked by parasites?

First a Th1 response, which is quickly changed to a Th2 response. After 2-3 months Th2 response is downregulated to a Treg response.

Explain antigenic diversity and antigenic variation

Diversity = different alleles for one gene between a specie
Variation =  multiple copies of one gene in an organism

Explain the life cycle of Cysticercosis

This is a tapeworm. Two species: solilum (pork) and saginata (cattle). People get infected when they eat meat that is not well coocked.

Worms have both female and male organs (hemaphrodite) and they release small peaces of their tail that are excreted via the stool. These small pieces break open in the environment, which releases eggs.

Explain the life cycle of dracunculiasis

This parasite lives in the water and when humans drink unfiltered water they get infected. The copepod dies and larvae are released and penetrate the stomach and intestine, where they mature and reproduce. Fertilized female worms travel to surface of the skin and discharge the larvae. Larvae are consumed by a copepod.

Through wich mechanism does pathology occur in malaria and schisto?

M: merozoites cause fever (immune response) and anemia because RBCs rupture. Merozoites can also cause organ failure when they get stuck in the organs or brain. The merozoites also produce products that bind to RBC, this causes the RBC to attach to the endothelial and this causes narrowing of the vessel.

S: eggs can get stuck in capillaries and cause an immune response.
Secreted products (CCA and CAA) also provoke an immune response
The cercariae reside several days in the skin, which causes an inflammatory reaction -> skin rash

The question on the page originate from the summary of the following study material:

  • A unique study and practice tool
  • Never study anything twice again
  • Get the grades you hope for
  • 100% sure, 100% understanding
Remember faster, study better. Scientifically proven.
Trustpilot Logo