Intro to endoparasites Flashcards
What is a parasite?
-an organism that lives on or in another living organism (host) -obtaining from it part or all of its nutrition or needs of existence -and imposing some degree of damage on host
What are microparasites?
-bacteria, viruses and fungi
Parasites are:
-Eukaryotic (defined nucleus and membrane bound organelles) -more evolutionary advanced organisms -have complex lifecycles
How have parasites evolved?
-co-evolved with their hosts over millions of years -longer evolutionary association = less damage to host -dangerous if infect wrong host
What parasites are host specific?
-Eimeria
What parasites can infest a wide range of host species?
-Sarcoptes scabiei
What can be their effect?
-chronic morbidity/ production losses
What are the parasite groups?
-Endoparasites (Protozoa, Helminths) -Ectoparasites
What are Protozoan parasites?
-single celled -microscopic -motile -often invade host cells
What are the 2 groups of protozoan parasites?
-Excavata -Trypanosoma spp. -Leishmania spp. -Giardia spp. -Trichomonas spp. -ALveolata -APICOMPLEXA
What are the 2 groups of Helminths?
-Phylum Platyhelminthes -Class Trematoda (fluke) -Class Cestoda (tapeworm) -Phylum Nematoda (roundworms)
Describe the features of helminths
-complex multicellular organisms -2mm-20m -do not multiply in mammalian hosts -usually cause chronic infection and disease
What are Trematodes?
- all in subclass Digenea -‘Digenetic’- means there are 2 or more generations in different hosts to complete the lifecycle
Describe the general adult morphology of a helminth
-2 suckers -blind-ended gut (no anus) -all hermaphrodite apart from schistosomes
Describe Cestodes
-segmented adults -1cm-20m -always parasitic -hermaphrodite
Describe cestode pathogensis
-adult worms rarely pathogenic -juveniles usually pathogenic (cysts in muscles, organs, tissues, eyes, brain)
How long are adult tapeworms?
-1cm-20m long
Describe Nematode adult morphology
-all are dioecious
Describe parasite lifecycles
-if only 1 host lifecycle is DIRECT -if 2+ hosts lifecycle is INDIRECT
What is the DEFINITIVE HOST?
-host in which the adult reaches maturity (+sexually reproduces)
What is the INTERMEDIATE HOST?
-host harbouring developing stages
What is pathogenesis?
-the biological mechanisms leading to a disease state
What is parasite pathogenesis?
-how a parasite infection causes disease
What are the features of parasitic diseases?
-usually long term and chronic -mortality usually only occurs after long period of sickness -disease severity often depends on parasite burden -pathology may simply be a side effect of infection/ OR an adaptive strategy to enhance parasite transmission
What is trypanotolerant?
-survive in tsetse-trypanosome infested areas
Which species are trypanotolerant?
-N’Dama cattle -Djallonke sheep -West African Dwarf goats
Does Bos indicus or taurus show more resistance?
-Bos indicus
Name other host factors
-Immunosuppression -Co-infections -Nutritional status
How do parasites cause disease?
-cause trauma to host cells, tissues and organs -change cell growth patterns- necrosis, hyperplasia, hypertrophy, metaplasia -divert host resources -produce toxins -induce host immune responses -transmit other infections -enable secondary infections to establish
Can parasites be good for the host?
-Hygiene hypothesis: -exposure to a wide range of pathogens crucial for a proper immune response -as sanitation improves, exposure to pathogens declines -results in increased immune disregulation with concomitant rise in allergies and autoimmunity
What is this structure?
-Apicomplexa
What is this?
-tapeworm
What is this?
-roundworm
What is this?
-fluke
What is this?
-fluke
What is this?
-tapeworm
What is this?
-adult tapeworm
What is this?
- adult nematode
- females have vulva
- both have anus and mouth
Describe the general lifecycle of trematodes
Describe the general lifecycle of cestodes
