APICOMPLEXA Protozoa characterized by the presence of an apical complex which allows the organism to invade host cells

Very well adapted to be intracellular in majority of their life stages. Reproduction both sexual and asexual. Haploid most of their lives, only zygote is diploid. Three major groups: gregarines coccidia piroplasmas

Developmental Stages of Coccidians Sporogony, sporocysts are usually made outside body and directly ingested by new host. Coccidian are usually distinguished by the number of sporocysts within the oocyst Merogony, merozoites Gamogony, gametocytes

Intestinal Coccidia Eimeria tenella Kingdom Protista Subkigdom Protozoa Phylum: Apicomplexa Class: Coccidia Order: Eimeriida Family: Eimeriidae Genus: Eimeria Species: tenella

Lives and multiplies within epithelial cells of the intestine ingestion Few days Unsporulated oocyst In feces, uninfective Sporulated oocyst In feces, infective Excystation Asexual reproduction merozoites

5.5 days 7 days sporozoite Micro- and macro-gametes 1st gen. merozoites 5.5 days 2nd gen. merozoites 7 days 3rd gen. merozoites

Look at slides 97 and 98. You should see the different stages in the intestine of a bird. Identify the epithelial cells of the intestine with the 4X lens, then zoom in. Slide 97 is a 5.5 day old infection, you should be able to see 2nd and 3rd generation of merozoites within the intestinal cells, and bursting out of them, some will be within cysts. On slide 98 you will see a 7 day old infection in which you should be able to recognize micro- and macro-gametes.

Intestinal Coccidia Toxoplasma gondii Kingdom Protista Subkigdom Protozoa Phylum: Apicomplexa Class: Sporozoasida Order: Eucoccidiorida Family: Sarcocystidae Genus: Toxoplasma Species: gondii

Toxoplasma gondii has very low host specificity, and it will probably infect almost any mammal. An obligate intracellular parasite . Definitive hosts are cats, which are infected by eating rodent intermediate hosts

Next host inhales the oocyst human, cat, cattle, sheep Life cycle sporulated Next host inhales the oocyst human, cat, cattle, sheep unsporulated Intestinal phase in cats only tachyzoites Extraintestinal phase

New host: cat and/or human Ingestion of raw meat Bradyzoite, in brain tissue New host: cat and/or human sporulated Inhalation of oocysts unsporulated

Examine slide 100. You should see bradyzoite or a tissue cyst full of bradyzoites

Ultraestructure of Toxoplasma gondii