Introduction to Parasites Flashcards
(34 cards)
Define parasite
A parasite is 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 three main clases of parasites?
Arthropods
Helminths
Protozoa
Discuss the lifecycle of Arthropods
Four distinct stages in the life cycle: egg, larva, pupa, and adult.
Adults lay eggs from which larvae hatch.
The larval forms grow and shed their skins (moult) several times, each time to accommodate their increases in size.
Eventually a hard-cased structure called a pupa is formed, which may have the capacity to survive winter.
The pupa hatches into the adult parasite, the final stage of metamorphosis.
Name the important characteristics of an arthropod
They possess an exoskeleton.
They have jointed appendages.
Their body is segmented.
They are bilaterally symmetrical.
They possess an open circulatory system.
Describe helminths
The helminths are invertebrates characterized by elongated, flat or round bodies.
What are examples of helminths?
Parasitic worms - many intestinal
Ringworm
Hookworm
Whipworm
What are the different types of helminths?
Nematodes - Round worm
Cestodes - Tapeworms
Trematodes - Flatworms
What is the life cycle of helminths?
Eggs
Larvae
Adults
What is the diagnosis of nematodes?
Press adhesive sellotape against perianal region
What is the lifecycle of Ascaris lumbricoides - nematode?
Ingested eggs hatch in the intestine, larvae carried by circulation to the lungs, swallowed again, adult worms develop in and inhabit small intestine
What are the various methods of ingesting a tapeworm?
Larval cysts ingested in meat, ingest eggs in dog faeces
Where is there a high incidence of Schistosomiasis?
A disease caused by parasitic worms.
Near fresh water, snail is important in the life cycle intermediate host
What accompanies a helminth infection?
Eosinophilia
Elevated IgE
What is a protozoa?
Protozoa are single celled organisms.
What is the mode of protozoa transmission?
Intestinal parasites - fecal - oral route
Blood parasites - arthropod vector
What is the mode of protozoa transmission?
Intestinal parasites - fecal - oral route
Blood parasites - arthropod vector
What is the species responsible for malaria (a type of protozoa)?
Plasmodium falciparum
What is the vector for malaria?
Anopheles mosquito
What is the life cycle of malaria?
Sporozoites are injected under the skin by the mosquito, they travel through blood and enter the liver, they mature in the liver and re-enter the circulation as merozoites.
Merozoites invade red cells, multiply and lyse cells
What is the diagnosis of amoebic dysentery?
Cysts in formed stool - microscopy
Diarrhoea with blood and pus
What type of disease is Amoebic Dysentery responsible for?
Intestinal and extra-intestinal infections
Liver abscess in late disease
What infection is caused by the bite of sandflies?
Leishmaniasis
What is cutaneous or muco-cutaneous leishmaniasis characterised by?
Skin or mucosal ulceration
What is Viceral leishmaniasis caused by?
Fever weight loss and hepato-splenomegaly
