see also:

• microbiology
• zoonoses
• Antihelminths
• the febrile returned traveller
• could some helminths be good for you?

• NB. unicellular or acellular animals (eucaryotic);
• sarcomastigophora (motile elements)
  • amoebae (pseudopods)
    • Entamoeba (anaerobe) - causes amoebiasis
    • Naegleria (aerobe) - may cause meningitis from thermal baths
    • Hartmanella (aerobe) - may cause meningitis from thermal baths
  • flagellates (flagella)
    • intestinal
      • Trichomonas eg. Trichomonas vaginalis - a cause of sexually transmitted infections (STDs/STIs)
      • Giardia may cause gastroenteritis, see giardiasis
    • visceral/blood
      • Trypanosoma - Trypanosoma brucei causes sleeping sickness; Trypanosoma cruzi causes Chagas disease
      • Leishmania - may cause cutaneous lesions from sandfly bites
• 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

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

• 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

• 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

• insects that attach or burrow into the skin and remain there for relatively long periods of time (e.g., weeks to months) such as:
  • ticks in Australia
  • fleas
  • lice
  • scabies and other mites