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24 Cards in this Set
- Front
- Back
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What is parasitism?
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The activity of an organism that spends any portion of its life in direct contact with a host species at the EXPENSE of the host
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What are the two groups of parasites?
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Protozoa and helminths
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What can helminths be divided into?
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Platyhelminthes (flatworms) and nematodes (round worms)
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What is a DALY?
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A disability adjusted life year. Some parasites don't cause many deaths but have severe DALYs - e.g. causing blindness
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Give three examples of protozoa (5)
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Malaria
• Trichomonas vaginalis • Trypanosomiasis • Leishmaniasis • Toxoplasmosis |
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Give two examples of helminths
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Lice and fleas
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How can parasites be transmitted? (4)
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Environmental (direct contact)
Via consumption Via direct invasion Insect vectors |
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What does trypanosome induce?
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Cardiac failure
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What is Toxoplasmosis?
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A parasitic disease caused by the protozoan Toxoplasma gondii
Infected by eating infected meat, by ingestion of feces of a cat that has itself recently been infected May cause some ?behavioural changes/role in schizophrenia |
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Give five examples of protozoa
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• Malaria
• Trichomonas vaginalis • Trypanosomiasis • Leishmaniasis • Toxoplasmosis |
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What are the four species of malaria?
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– Plasmodium falciparum
– Plasmodium vivax – Plasmodium ovale – Plasmodium malariae Falciparum malaria responsible for most deaths and severe disease |
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Where does the sexual cycle of taxoplasmosis occur?
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Sexual cycle only occurs in cats but all vertebrates are
susceptible |
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What does reactivation of a toxoplasma cyst indicate?
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Immunosuppression; HIV or transplantation
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What are the three species of Trichomonas and where are they found? What does Trichomonas cause?
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T. hominis caecum / large intestine
– T. tenax mouth – T. vaginalis ♀vagina, urethra ♂urethra, seminal vesicles & prostate T. vaginalis results in inflammation and discharge and affects ~180 million women |
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What does Trypanosomiasis cause?
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Chagas disease
• Cardiac failure • Loss of nervous control of gut Fever, malaise, anorexia. Invasion of CNS results in sleeping sickness phase of disease • Both sub species demonstrate variable surface coats associated with avoidance of host immune response |
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What does Lieshmaniaisis cause?
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Cutaneous diseases, deeper tissue may be
implicated Simple cutaneous lesion localises at site of bite resulting in a granulomatous response • Epidermis fragile and prone to further physical damage, ulceration and secondary infection |
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What are diseases caused by larval cestodes?
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Larvae in organs results in disease
– Spirometra spp. Invasion of deep tissues – Taenia solium cysticercosis, invasion of range of tissue but prediliction for brain – Echinococcus granulosus, hydatid disease, liver and lung infections |
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How do cestodes cause disease? Give examples
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Due to worms in the gut
– Diphyllobrothrium latum; lumen of small intestine – Taenia saginata; beef tapeworm, lumen of small intestine, 5-20 m long. 60 million cases worldwide – Taenia solium; pork tapeworm, small intestine – Hymenolepis nana; dwarf tapeworm, small intestine, 40 mm long. >2000 worms per infection – Disease associated with competition for nutrients & physical blockage |
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What do Digeneans cause? What is their appearance?
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Swimmers itch. Flattened, oral sucker, ventral sucker
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What do the different Schistosomiasis cause? Where are they found?
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Schistosoma mansoni intestinal disease
– Schistosoma haematobium urinary didease – Schistosoma japonicum intestinal disease – Schistosoma intercalatum intestinal disease, restricted foci in Africa • Located in the lumen of blood vessels • Female permanently in ventral groove of male; gynaecophoral canal • Adaptations to evasion of host immunity • Pathology associated with granulomatous lesions |
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What are the intestinal nematodes? What's its life cycle?
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Intestinal nematodes
• Ascaris lumbricoides • Hookworms – Ancyclostoma duodenale / Necator americanus Life cycle: Egg –L1- L2- L3- L4-adult |
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How are Filariasis spread? What do they cause?
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Require larval passage through insect
vector • 4 major species – Lymphatic disease: • Wucheria bancrofti, Brugia malayi – Blindness: • Onchocerca volvulus, Loa loa |
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What do Lymphatic filariasis cause in juveniles and in adults?
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Adults; afferent lymphtic vessels
Juveniles; blood dwelling, sheathed microfilariae Inflammation and immune responses to worms – Lymphatic inflammation, pain, fever – Elephantiasis • Chronic lymphoedema • Fibrous infiltration • Thickening of the skin |
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What does Onchoceriasis cause?
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River blindness
– Onchodermatitis – Both result from immune response to microfilariae – Unsheathed microfilariae found in skin leading to nodular formation – Skin changes; increased pigmentation, loss of elasticity, hanging groin, pouches under eye – High vector density 30% blindness |
