Apicomplexa

• Phylum Apicomplexa


  • uses apical complex - body flexion, gliding, undulation or longitudinal ridges
• Suborder Eimeriina


  also known as Coccidians
• Sporogony


  sexual reproduction
• Schizogony


  asexual reproduction
• Merogony


  producing merozoites (meronts)
• Gametogony


  development of male (micro) and female (macro) gametocytes (gamonts)
• Coccidia


  causes coccidiosis (problem in animal farming and in zoo)
• Coccidia


  • microscopic
  • spore-forming
  • single celled obligate intracellular protozoan
  • considered opportunistic in immunocompromised and immunodeficient individuals
  • infects intestinal tract
• Species belongs to Coccidians

  • Cryptosporidium parvum
  • Cyclospora cayetanensis
  • Cytoisospora belli
  • Sarcocystis hominis
  • Sarcocystis suihominis
  • Toxoplasma gondii
• Cryptosporidium spp


  causes Cryptosporidiasis (Diarrhea illness)
• Cryptosporidium spp


  • protozoan pathogen of Phylum Apicomplexa
  • does not require vector
  • complete its life cycle within single host
  • oocysts with 4 sporozoites
• Cryptosporidium spp that causes disease in human

  • Cryptosporidium parvum
  • Cryptosporidium hominis
• Cryptosporidium spp.


  Life cycle:

  • has spore phase (oocysts)
  • complex
• Diagnosis for Cryptosporidium spp.

  • Fecalysis
  • DFS
  • FECT
• Isospora spp.


  causes Isosporiasis, Isosporosis / Intestinal Coccidia
• Isospora spp.


  • internal parasite
  • atleast 248 species been described
  • elliptical, with sharpened ends
• Isospora spp.


  life cycle:

  • involves asexual and sexual stages
• Treatment for Isospora spp.

  • Sulfadiazide + Pyrimethamine (DOC)
  • Cotrimoxazole + Sulfamethoxazole (Alternative drug)
• Toxoplasma gondii 


  causes Toxoplasmosis
• Toxoplasma gondii

  definitive host is cat
• Life cycle of Toxoplasma gondii

  • sexual (takes only on cats)
  • asexual (any warm blooded animals - int. host = rodents are typical)
• Toxoplasma gondii

  • group of obligate intracellular parasites
  • have complex organelles
  • communicable zoonotic pathogen

  3 forms:

  • oocysts
  • trachyzoite
  • bradyzoite (tissue cysts)
• 3 Primary transmission / MOT of Toxoplasma acc. to CDC

  • Food borne transmission
  • Congenital toxoplasmosis (mother to child)
  • Zoonotic transmission
  • Organ transplant and blood transfusion
• Cyclospora cayetanensis


  • cyst forming coccidians
  • causes self-limiting diarrhea
  • has special oocysts
  • thick wall with an outer threadlike coat -> wrinkle
• MOT of Cyclospora cayetanensis

  fecal-oral
• Sarcocystis spp.


  • infect reptiles, birds, mammals
  • 130 recognized species
• Sarcocystis spp

  derived from greek work

  • sarx - flesh
  • kystis - bladder
• Sarcocystis hominis


  • rarely occuring protozoan
  • causes sarcocystis -> affectinig small bowel and muscle tissue
• Sarcocystis suihominis


  • man as definitive host
  • responsible for intestinal sarcocystis in human
• Infective stage of Cryptosporidium, Cyclospora, Isospora

  • Sporulated cysts
• Diagnostic stage of Cyrptosporidium

  Sporulated oocysts
• Diagnostic stage of Cyclospora and Isospora

  Unsporulated oocysts
• Cryptosporidium contains

  4 sporozoites
• Cyclospora contains

  • 2 sporoblast that has 2 sporozoite
• Isospora contains

  • 2 sporoblast
  • 4 sporozoites
• DOC for Cryptosporidium

  nitazoxanide
• DOC for Cyclospora and Isospora

  Cotrimoxazole