[2] Previously H. tvaerminnensis was wrongly identified as Octosporea bayeri Jírovec, 1936, a parasite of D. magna described in Czech Republic which was never found again.

[7][8] While its host D. magna is found all over the northern hemisphere, the two Hamiltosporidium species seem to have a limited geographic distribution.

[9] All stages of vegetative reproduction (merogony) are enclosed by a thick plasma membrane, which is in direct contact with the cytoplasma of the host cell.

The onset of the sporogony is the production of a sporophorous vesicle that is connected to the plasma membrane by tubules.

In advanced stages of the infection spores are found in the whole body cavity of host animals, which leads to a clearly visible whitish coloration.

The infection leads to reduction in the host fitness by reducing life expectancy, fecundity and competitive ability for resources among D.

[11][12] In H. tvaerminnensis horizontal transmission occurs after the host's death, when spores from decaying cadaver suspend in the water.

[13] This means that the parasite is hardly lost in a clone lineage and also survives inside the resting eggs of its host.

Because of its combined vertical and horizontal transmission strategies, H. tvaerminnensis can reach prevalence of up to 100% in asexual populations in nature as well as in the laboratory.