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parasites

parasites

classification of parasites

protozoa:

  • NB. unicellular or acellular animals (eucaryotic);
  • sarcomastigophora (motile elements)
  • ciliophora (cilia)
    • Balantidium
  • sporozoa (non-motile, alternate sexual/asexual cycles)
    • Plasmodium - see malaria
    • Toxoplasma - mainly through contact with cats, a potential issue during pregnancy see toxoplasmosis
    • Pneumocystis - Pneumocystis carinii is a significant cause of pneumonia in the immunocompromised such as those with HIV / AIDS

metazoa (helminths):

  • NB. multicellular animals (worms, insects, etc.);

flat worms:

  • monogeneans:
    • very small parasitic flatworms mainly found on skin or gills of fish, and also in the urinary bladder and rectum of cold-blooded vertebrates.
    • none infect birds, and only one (Oculotrema hippopotami) infects mammals, parasitizing the eye of the hippopotamus.
  • Trematodes (flukes) - watersnails eat eggs → cerceriae;
    • Schistosoma (invade skin if swim→adults in venous complexes) - see schistosomiasis
    • Fasciola (aquatic plant ingested→adults in liver)
    • Opistorchis (raw fish ingested→adults in liver)
    • Paragonimus (raw crustaceae ingested→adults in lung)
  • Cestodes (tapeworms)
    • Taenia
      • saginata (rare beef ingested → adult in GIT)
      • solium (rare pork ingested→adult GIT→cysticerci tissues)
    • Echinococcus (dog faeces ingested→hydatid cysts liver, etc) - see echinococcosis (hydatids)
    • Hymenolepis

Round worms (Nematodes):

  • No intermediate host
    • Direct infection
      • Enterobius (pinworm) - a major problem with school children
    • Soil maturation needed
      • Trichuris (whipworm) (caecum);
      • Ascaris (adult small bowel→larvae lungs)
      • Ancylostoma & Necator (hookworms) (skin→lung→duodenum)
      • Strongloides (skin→lung→GIT) - see strongyloidiasis
      • Toxocara
  • Intermediate host needed
    • Trichinella (rare pork→jejunal mucosa)
    • Anisakis (raw fish → GIT)
    • Dracunculus (ingested water flea → GIT → skin)
    • Angiostrongylus (eat snails→liver→heart/lungs/CNS) ⇒ angiostrongyliasis
      • most common cause of eosinophilic meningitis in SE Asia and Pacific Basin
    • filariae cause filariasis
      • Onchocerca volvulus (biting black fly)(skin itch→LN→“river blindness” see onchocerciasis / river blindness)
      • Onchocercidae Loa Loa (biting deer flies and yellow flies) ⇒ Calabar swellings, itching, swelling in the eye
      • Wuchereria bancrofti (mosquitoes)(adult in lymph→pre-larvae blood/lung ⇒ elephantiasis)
      • Brugia (mosquitoes)(as for Wuchereria)
      • Dirofilaria (mosquitoes)(die readily in man→granuloma lung)
      • Mansonella

ectoparasites

parasites.txt · Last modified: 2022/05/11 22:02 by gary1

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