Parasitology Flashcards
What is a parasite ?
A parasite is an organism which lives on /or in a host organism and it gets its food from or at the expense of its host
For e.g some parasites live on the skin
What are the three groups of parasites ?
Protozoa
Helminths
Ectoparasites
Define Protozoa
Protozoa are microscopic single celled organisms that can be free -living or parasitic in nature
They can multiply in humans which causes serious infections to develop from a single organism
Outline the different protozoa transmission routes
Transmission :
Protozoa living in the human intestine can be transmitted by the faecal-oral route
Protozoa living in blood or tissues are transmitted by an arthropod vector
(e.g. mosquitos-malaria))
What are the different types of protozoa and how are they classified ?
Types of protozoa are classified by their mode of movement :
Amoeba - Entamoeba
These project pseudopodia
Flagellates -Giardia,Leishmania
These have flaggellar movement
Ciliates - Balantidium
These have hundreds of cilia and beat in unison to propel through the water
Sporozoa -Organisms whose adult stage is not motile
Plasmodium, Cryptosporidium
What are some medically important protozoa infections?
Entamoeba histolytic amoebic dysentary
This causes ulcers in the large intestine.
Large ulcer which digs under the epithelial into the mucosa.
They are in the epithelial sub mucosa layers.
Giardia lamblia- Cause diarrhoea with blood
Trichomonas vaginalis-
Causes infections in the genital tract
malaria -Plasmodium spp.)
Toxoplasma gondii
Cryptosporidum
Leishmania spp.
Trypansoma cruzi
Trypanosoma brucei (gambiense /rhodiense )
What are helminths infections ?
Helminths are large multicellular organisms (Worms) generally visible to the naked eye in adult stages
In adult form , they cannot multiply in humans. The parasite burden depends on amount of exposure to environment
The most common intestinal worm infection is Ascaris Lumbricoides.
What are the three categories of worms which infect humans ?
- Nematodes (round worms)
- Trematodes(flukes)
- The male is the larger parasite
- Cestodes (Tape worms )-very long parasites
What are some medically important helminths?
Nematodes
Soil-transmitted helminths
- Ascaris lumbricoides
- Trichuris trichiura
- Hookworm spp.
- Enterobius vermicularis
Filarial parasites
- Wuchereria bancrofti
- Loa loa (eyeworm infection)
- Onchocerca volvulus( blinding eye infection)
- Dracunculus medinensis
Others:
- Toxocara canis/cati
- Trichinella spiralis
What are some medically important helminths-Trematodes and Cestodes
Trematodes
- Schistosoma mansoni/haematobium/japonicum
- Clonorchis sinesis
- Fasciola hepatic
- Paragonimus spp.
Cestodes
- Taenia saginata
- Taenia solium
What are ectoparasites?
These are blood sucking arthropods such as ticks,fleas lice and mites that attach or burrow into the skin and remain there for a long period of time (Weeks-months)
Outline some medically important ectoparasites
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What is schistosomiasis?
People wash/swim in water contaminated by which will invade the skin and end up in portal venous system or bladder venous system.In the bladder they mate and the eggs are mushed through mucosa into the urine and released through urination
What are some determinants of parasite infections ?
Depends on mode of transmission and opportunities for transmission
Faeco-oral :
Household sanitation
Access to clean water
Personal hygiene behavious
Food :
Animal Husbandry
Surveillance
Regulations and government controls
Outline the life cycle of Trypansoma cruzi
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