Cystoisospora belli

A fully mature (sporulated) oocyst of genus Isospora is a spindle-shaped body that has two sporocysts that contain four sporozoites each. The oocysts of Cystoisospora belli are long and oval shaped. They measure between 20 and 33 micrometers in length and between 10 and 19 micrometers wide. == Life cycle ==

• An oocyst with one sporoblast is released in stool of infected person • After the oocyst has been released, the sporoblast matures further and divides into two • After the sporoblasts divide they create a cyst wall and become sporocysts • The sporocysts each divide twice, resulting in four sporozoites • Transmission occurs when these mature oocysts are ingested • The sporocysts excyst in the small intestine where sporozoites are released • The sporozoites then invade epithelial cells and schizogony is initiated • When the schizonts burst, merozoites are released and continue to invade more epithelial cells • Trophozoites develop into schizonts, containing many merozoites • After about one week, development of male and female gametocytes begin in the merozoites • Fertilization results in the development of oocysts, which are released in the stool The sporulation time of this parasite's egg is usually 1–4 days, and the entire life cycle takes about 9–10 days. The infective stage found in stool is the mature oocyst. == Symptoms ==

Immune competent individuals are usually asymptomatic to this parasite's infection. But clinical symptoms such as mild diarrhea, abdominal discomfort, and low grade fever for approximately one week has been observed in some individuals. == Diagnosis and treatment ==

Cystoisospora belli is diagnosed by identification of the oocyst through examining a stool sample under a microscope. The diagnostic stage is the immature oocyst that contains a spherical mass of protoplasm. In other words, the oocyst that is diagnosed in the stool sample is unsporulated, and contains only one sporoblast. == Transmission and prevention ==

Cystoisospora belli does not require an intermediate host and currently is only known to transmit from person to person. The method of transmission is ingesting food or water that has been contaminated with feces from someone who is infected. == History ==

Isospora belli was discovered by Rudolf Virchow in 1860 and was named by Charles Morley Wenyon in 1923. The parasite is now known as Cystoisospora belli. ==References==