INTESTINAL PARASITES (Protozoa)
SPOROZOEA Order: Eucoccidiida

SARCOCYSTIS Spp.

sarc1-ic

Sarcocystis spp.: protozoa of the genus Sarcocystis have two distinct life cycles:
carnivores are final hosts while herbivores are the intermediate hosts; omnivores,
such as humans serve as both intermediate and definitive hosts of the coccidian.
Humans may become infected by two species, S.hominis and S.suishominis.

sarc2-ic

Sarcocystis spp. (life cycle): when infective oocysts and sporocysts,
wich are excreted with faeces by the definitive hosts, are swallowed
by another susceptible host (the intermediate host),
sporozoites are released and migrate to vessels
where they develop into two generation of meronts.
Two sporulated sporocysts containing 4 sporozoites.
Sporocysts measure 15-19 by 8-10 µm.
Wet mount preparation.

sarc3-ic

Sarcocystis spp.: merozoites emerging from the second generation meronts
enter the mononucleate cells where they develop by endodyogeny.
Merozoites subsequently released enter muscle cells and neural tissue
where they develop to mature sarcocysts.
Two sporulated sporocysts containing 4 sporozoites.
Sporocysts measure 15-19 by 8-10 µm.
Wet mount preparation in relief.

 

Sarcocystis 1

Sarcocystis spp.: mature sporocyst containing four sporozoites in faeces (unstained).

sarc4-ic

Sarcocystis spp. (pathology): intermediate hosts are the most affected
by Sarcocystis in terms of disease.
20-40 days after ingestion of sporocysts and subsequent migration
of sporozoites throught the body vessels, acute lesions
(edema, hemorrhages and necrosis) develop.
Lesions are associated with maturation of second generation
of meronts within the endothelial and subendothelials cells.
Two sporulated sporocysts containing 4 sporozoites.
Sporocysts measure 15-19 by 8-10 µm.
Wet mount preparation.

sarc5-ic

Sarcocystis spp.: (pathology): the most common pathological alterations
observed are myositis, petechial hemorrhages of heart and serosae,
edema, necrosis and hemorrhages of lymph nodes.
After the acute phase cysts of Sarcocystis may be found in
various muscular tissues, generally without pathology.
Most definitive hosts do not show any clinical sign or symptoms.
In some issues mononuclear infiltration or hyperemia
have been observed in the lamina propria of the small intestine.
Two sporulated sporocysts containing 4 sporozoites.
Sporocysts measure 15-19 by 8-10 µm.
Wet mount preparation in relief.

Sarc_09-50	Sarc_06-100	Sarc_07-250

Sarc_08-250	Sarc_13-400

Sarcocystis infection is common in domestic animals.
Symptomatic disease in humans is rare; cysts are detected as incidental
findings at autopsy or in a biopsy containing muscle, performed for other
diagnostic purposes. There is no inflammatory reaction around the cysts.
Basophilic intramuscural sarcocystis.