Parasitic Infections Flashcards
what is the definition of invasion?
invasion by and growth of pathogenic microorganisms
what is the definition of disease?
a disordered or incorrectly functioning organ, part, structure or system of the body resulting from the effect of genetic or developmental errors, infection, poisons, nutritional deficiency or imbalance, toxicity, or unfavourable environmental factors; illness; sickness; ailment.
what is the definition of parasite?
organism living in/on a host and is dependent on the host’s function for nutrition and may cause damage
what are the 2 major classes of parasites?
endo- and ectoparasites
endoparasites split into Protozoa and Metazoa (helminths)
what is the main difference between an endo- and ectoparasite?
ectoparasite lives on the surface of the host whereas endoparasite lives inside the body of the host.
what are the major parasitic protozoa?
1) amoeba e.g. entamoeba histolytica
2) coccidia e.g. plasmodium
3) ciliate e.g. balantidium
4) flagellates e.g. giardia
what are the major parasitic metazoa?
roundworms
flatworms
flukes.
what are the features of parasitic protozoa?
- single-celled organisms
- eukaryotic organisms i.e. complex organelles, genome in nucleus
- varied pathogenesis
- some use insect vectors
- no eosinophilia
what are the feature of parasitic metazoa?
- multicellular organisms
- free living, have intermediate hosts and vectors.
- some just inhabit the gut (geo-helminths) whilst other invade tissues
- eosinophilia if they invade the blood
what is the main haematological difference in protozoa and metazoa infection?
protozoans will not cause eosinophilia
metazoans will cause eosinophilia
examples of protozoa:
- amoeba
- coccidia
- cilliate
- flagellate
- amoeba: entamoeba histolytica and entamoeba dispar
- coccidia: plasmodium, toxoplasma, cryptosporidium
- ciliates: Balantidum coli
- flagellate: Giardia lamblia, Trichomonas, Leishmania
what is a vector?
an organism that transmits a disease or parasite from one organism to another
name examples of vectors and the diseases they transmit?
1) Snail
– transmits schistosomiasis (Fluke, Metazoa, endoparasite).
2) Female anopheles’ mosquito
– transmits malaria (Coccidia i.e. plasmodium protozoa, endoparasite).
3) Chrysops (deer flies)
– transmits Loiasis (Roundworm, Metazoa, endoparasite).
name 2 amoeba (Protozoa) and the diseases they cause
what is the treatment?
Entamoeba histolytica and Entamoeba dispar
– cause ulcers.
(ingestion of mature cysts in food or water, or on hands. Humans are the only reservoir)
treatment: Nitroimidazole derivatives, parmomycine or diloxanide furoate
name 3 coccidia (Protozoa) and the diseases they cause
1) Plasmodium
- malaria (fever, headache, chills, emesis, myalgia, anaemia)
2) Toxoplasma
- mild disease in immunocompromised
3) Cryptosporidium
- diarrhoea, fever, nausea, emesis