Parasitology Flashcards
What is a parasite?
An organism that lives on or in a host organism and gets its food from or at the expense of its host
What are the different types of hosts for parasites?
- Intermediate – host in which larval or asexual stages develop
- Definitive – host in which adult or sexual stage occurs
When are vectors mechanical?
○ Mechanical when no development of parasite in vector
When are vectors biological?
○ Biological when some stages of life cycle occur within the vector
What are the 3 classes of parasites?
- Protozoa
- Helminths
- Ectoparasites
What are protozoa?
• Microscopic, single celled organisms that can be free-living or parasitic in nature
What are protozoa able to do in humans??
• Able to multiply in humans allowing serious infection to develop from single organism
§Not all parasites can multiply in humans but protozoa can
What are the ways protozoa can be transmitted?
○ Protozoa living in the human intestine can be transmitted by the fecal-oral route
○ Protozoa living in blood or tissues are transmitted by an arthropod vector
What are protozoa classified by and what are they?
• Protozoa are classified by modes of movement
○ Amoeba e.g. Entamoeba
§ Has pseudopodia and moves around by pushing them out
○ Flagellates e.g. Giarda, Leishmania
○ Ciliates e.g. Balantidium
○ Sprozoa – organisms whose adult stage is not motile e.g. plasmodium, cryptosporidium
What does entamoeba histolytica cause?
○ Causes amoebic dysentery
What does a loss of epithelia due to entamoeba histolytica cause?
○ Loss of epithelia so causes ulcer formation
What does giardia lamblia cause?
○ Cause diarrhoea
What happens to the villi of the small intestine due to giardia lamblia?
○ Blunting of villi in small intestine
What does trichomonas vaginalis cause?
causes vaginal discharge
What is toxoplasma gondii an infection from?
○ Infection from cat faeces
What is cryptosporidium a common cause of?
○ Common cause of epidemic diarrhoea worldwide
What is cryptosporidium a major cause of?
○ Major cause of moderate-severe diarrhoea in developing countries
What can cryptosporidium do to growth?
Can cause growth stunting
What are soil transmitted helminths?
○ Ascaris lumbricoides
○ Trichuris trichiura
○ Hookworm spp
○ Enterobius vermicularis