Platyhelminths Flashcards
What are the groups of Platyhelminths?
- Turbelleria
- Cestodes aka Tapeworms
- Trematodes aka Flukes
- Monogenea
What is the immune response of Helminths?
- Helminths induce the development of effected Th2 cells
- Th2 are characterised by: IL-4, IL-5, IL-9, IL-13 and IL21 and the absense of IFNgamma and IL-17
- Naive CD4+ T cells can differentiate into several types of effector and regulatory cells during helminth infection
- Specific cytokines and TF contribute to differentiation and expansion of cell populations which determiknes wether it provides host protection or pathological inflammation
- Exposure to IL-12 procued by APDC induces Th1 differentiation –> IFNgamma = unable to clear parasites
Strong Th2 response= increase resistance and immunity against parasite infections
What is the “old frineds hypothesis” in regard to helminth infection?
Refers to the microbes that have evolved alongside the mammalian system, and be involved in host immune defence
- Species that co-exist in environment with humans
- Species which inhabit skin, gut, respiratory tract of humans and surrounding animals
- Organisms (viruses and helminths) that reside in a chronic carrier state in humans, and tolerated by immune system
What is ShK and how does it work?
What is it used for?
Potent Kv1.3 channel inhibitor from sea anemone (Stichodactyla helianthus)
Suppresses T-cell mediators in autoimmune diseases and organ rejection
Shk related peptides in parasitic worms (hookworm) and filarial worms (Brugia malayi)
- block human Kv1.3 channel in T-cells
- suppress IFNgamma production in human T lymphocytes
- potential for use in human autoimmune therapy
Tell me about the Monogenea, Diplozoon paradoxum
- Monogenic fluke which shows complete monogamy
- It cannot develop further unitl it encounters another one
- When they encounter another they fuse by attaching sucker to dorsal papilla on one another
- Fusion stimulates maturation
- Gonads then appear which then allow cross-fertilisation
What is the competition with trematodes?
Co-infections of different parasite species within the same host like a snail can cause competitions between rediae and sporocysts (rediae are dominant to sporocysts as have mouths and are therefore able to feed)
What are the Tissue flukes (trematode) groups?
Fascioliasics (affects humans)
Fasciola hepatica
Fasciola gigantica
Fasciolopsis buski
Paragonimus westermani
What is Coracidia?
The oncosphere of a tapeworm at the time of hatching while it is still surrounded by embryophore
Whats an oncophere?
Has 6 hooks and is the earliest differentiated stage of a tapeworm
What are examples of monogenea?
Diplozoon paradoxum
Gyrodactylus salaris
Oculotrema hippopotami (the only mammalian one)
What is the subgroups of the Turbellaria platyhelminths?
Rhabditophora –> Neodermata –> Monogenea mono, Eucestodes and Digenea
What are the different blood flukes (trematodes)?
Schistosomes –> Intestinal and Urogenital
Intestinal= Schistosoma mansoni, S. Japanicum, S. mekongi, S. guineensis
Urogenital= S. haematobium
What are the controls and preventions for infection by Cestodes i.e. Taenia solium
Prevention for cysticercosis
- wash hands reguarly
- Wash fruit and veg
- When travelling dring bottled, filtered water
- Cook meat well
- Don’t thaw
- Freeze well
What is the pathogenesis for cestodes?
Treatment?
Swallowed tape worm eggs –> Eggs get into tissue like the muscle and brain –> cysts form (called Cysticerci)
Treatment: anti-parasitic drugs in combination with anti-inflammatory drugs
What is the prevention and control for blood flukes i.e., schistosomiasis?
- If in area where it is common then avoid swimming in fresh water
- Drink safe water
- Boil water
- Vigarous towel drying if do go into fresh water
