Protozoology lab

• Sarcodina

  Amoeboid locomotion by pseudopodia
• Entamoeba histolytica


  • The only parasite in this laboratory possessing amoeboid movement (in the trophozoite form)
  • Can cause amoebic dysentery in humans in the Tropics

  
• Entamoeba histolytica


  • Trophozoites shed in watery faeces
  • Ulcer from the intestine

  
• Mastigophora


  Locomotion by one or more flagella
• Haemoflagellate parasites

  Of the blood generally transmitted by biting insects

  
• Leishmania spp.

  • Amastigote form is found in mammalian (human and dog) macrophages and other R.E.S cells
  • Promastigotes are found in the gut of sandfly vectors

  
• Leishmania


  • Amastigotes (free)
  • Amastigotes in smear
• Trypanosoma cruzi


  • The agent for Chagas' disease is transmitted between the range of triatomid bugs and more than 100 mammalian species (reservoir hosts)
  • Causes disease in dogs and humans

  
• Trypanosoma cruzi

  • Amastigotes in cardiac muscle
  • Trypomastigotes observed in blood film from a dog
• Flagellates

  Predominantly of the Intestines
• Histomonas meleagridis


  • Causes "blackhead" in young turkeys
  • Transmitted in the egg of the poultry nematode Heterakis gallinarum, the caecal worm

  
• Histomonas meleagridis


  • Caecum from a turkey poult
  • Damaged liver from a turkey poult
• Giardia lamblia


  • Common intestinal flagellate infecting a wide range of mammals
  • Encysted form and trophozoites are detected in faeces using faecal wet smear stained with iodine
• Giardia lamblia


  • Trophozoite
  • Cyst
• Hexamita (Spironucleus)


  Hole in the head
• Ciliophora


  Locomotion by Cilia
• Balantidium coli


  • Large relative to other enteric protozoa, and characterized by a sub circular shape, cilia and a large nucleus
  • Forms resistant cysts to facilitate contaminative transmission

  
• Balantidium coli

  • Trophozoite
  • Cyst
• Apicomplexa (Sporozoa)


  Locomotion by Gliding
• Coccidia, Piroplasmidia, Haemosporidia


  Classes of Apicomplexa
• Coccidia (Eucoccidiorida)


  • Contains many genera of veterinary importance, namely Eimeria, Isospora, Cryptosporidium, Toxoplasma and Sarcocystis
  • Eimeria, Isospora, and Cryptosporidium have DIRECT life cycles
  • Toxoplasma and Sarcocystis have INDIRECT life cycles which involve an intermediate host

  
• Eimeria and Isospora

  • Genus Eimeria is of considerable veterinary importance, causing coccidiosis in mammals and birds
  • Multiplication inside the cells of the intestinal epithelium of the host, followed by release of the environmentally resistant oocysts in the faeces
  • Oocysts undergo sporogony outside the host before becoming infective
  • Diagnosis is by faecal smear and or floatation

  
• Mixed infection of Isospora and hookworms in dogs


  • Compare size of oocysts to GIN eggs

  
• Eimeria tenella infected caecum


  • Observe second generation schizonts on sub epithelium layer, and note the breakdown of the epithelial structures
  • Pathogenic for young chickens, causing caecal coccidiosis

  
• Eimeria tenella


  • Life cycle charts
  • Faecal smear with oocysts

  
• Cryptosporidium parvum


  • Common protozoal infection of a wide range of mammals, birds and reptiles
  • Recognized as an important cause of diarrhoea complex in claves, lambs piglets, puppies and foals
  • Humans can be infected, particularly those in an immune suppressed state
  • Oocysts sporulate within the host and auto-infection is possible
  • Diagnosis is achieved by performing a wet mount in a saturated sugar solution or by staining oocysts in faecal smears

  
• Cryptosporidium


  • Stained oocysts
• Toxoplasma gondii

  • Feline intestinal coccidian parasite
  • Causes abortion in sheep and is a serious zoonosis which can lead to congenital infection
  • Any bird or mammal, including humans, can act as intermediate host

  
• Toxoplasma gondii

  • Oocyst
  • Bradyzoite cyst in mouse brain
• Sarcocystis


  • Parasites have humans, domestic and wild carnivores as the final host and herbivores and swine as the intermediate host
  • May cause diarrhoea in the final host, but their importance is in causing condemnation of carcasses on account of the sarcocysts localized in skeletal muscle

  
• Sarcocystis


  • Cysts in cross section of muscle
• Hepatozoon spp.

  • Hepatozoon canis and H. americanum infect dogs
  • Acquired by ingestion of the brown dog tick, Rhipicephalus sanguineus
  • Gamonts are observed in the cytoplasm of neutrophils and monocytes in the peripheral blood
  • Schizonts are observed in the lungs, heart, skeletal muscle, liver, spleen and lymph nodes

  
• Hepatozoon spp.


  • Gamonts observed in the cytoplasm of the white blood cells in blood smear

  
• Piroplasmidia


  • Parasites of blood cells that have ticks as their vectors
  • Include the Babesia spp. and Theileria spp.

  
• Babesia


  • Invade the erythrocytes where they multiply by binary fission, destroying the red cell in the process, and releasing more parasites to invade other red cells
  • Many species that affect a wide range of domestic animals, and many are transmitted transovarially (vertically) in hard sticks
• Babesia canis


  • Large Babesia
• Babesia gibsoni


  • Small Babesia
• Haemosphoridia


  • Parasites of red and white cells as well as epithelial cells, which have blood-sucking dipteran flies as their vectors, and in which sexual reproduction occurs
  • Three genera, Plasmodium, Haemoproteus and Leucocytozoon are the cause of avian malaria
  • Plasmodium genus is also responsible for human malaria
• Plasmodium spp.


  • Transmitted by mosquitoes
• Leucocytozoon spp.


  • Transmitted by Simulium flies (blackflies)
  • Very large gametes occur in greatly distended RBC's while schizogony occurs in liver cells