[4] With this direct waterborne transmission, the parasite easily infects other hosts, so their prevalence is typically high and can reach up to 100% in natural populations.

[3][6] In comparison with other endoparasites of Daphnia spp., O. colligata is rather avirulent and does not drive infected host populations to extinction.

Therefore, the host needs to be dissected and its gut epithelium examined under a phase contrast microscope, to confirm infection.

O. colligata lives in epithelial gut cells in a large parasitophorous vacuole, which is formed by the host at the time of infection.

When these epithelium cells with parasitophorous vacuoles are shed in the gut, the parasite spores leave the host together with the faeces.

[1] The immature presporal stages, which are called merozoites, have a round or ovoid shape and measure 2.8 μm in diameter.

[1] Electron-dense secretions create a thick layer on the surface and tubular material (63-65 nm in diameter) is produced.

This pairwise structure leads to the interpretation of two sporoblast mother cells, which have failed to separate during the first division of the sporont.

The spore wall is significantly thinner at the anterior pole, where also the polar filament is attached to an anchoring disc.

The specific name colligata is derived from the Latin verb colligo, bind together, which refers to the connected sporoblasts and spores.