Haemogregarina

Haemogregarina is a genus of haemoprotozoans, parasitic mainly on cold-blooded vertebrates. They are unicellular organisms which are parasitic in the red blood cells.

History

It was described in 1885 by Danilewsky from the European pond turtle (Emys orbicularis).

General description

These parasites are generally considered non-pathogenic, and have been described in the red blood cells of desert tortoises. They are elongate to fusiform oval organisms found in the red blood cells. Although the size varies, they are larger than the cell’s nucleus. The organism stains a basophilic colour and has a surrounding clear zone.

Taxonomy

Four genera are recognised in this family.

Karyolysus
Haemogregarina
Hepatozoon
Cyrilia

The genera are distinguished on the basis of the sporogony in the invertebrate vector. However in many cases the vector is not known and the species have been allocated to the genus Haemogregarina sensu lato pending identification. This somewhat unsatisfactory situation may be improved by DNA sequence analysis in the near future. For this reason the species listed here may subsequently be moved to a new genus or even new family.

Genus Haemogregarina infects lower vertebrates (fish and reptiles) as intermediate hosts and leeches (as definitive hosts).

The following species are recognised:^[1]

References