**16. Classification**

#### **Taxonomy**

*Plasmodium* belong to the family plasmodium, order Haemosporidia and phylum Apicomplexa. There are currently 450 recognized species in this order. Many species of this order are undergoing reexamination of their taxonomy with DNA analysis. It seems likely that many of these species will be re-assigned after these studies have been completed. For this reason the entire order is outlined here.[38,39]

Order Haemoporida

Family Haemoproteidae


• Subgenus *Haemoproteus*

#### Family Garniidae

18 Malaria Parasites

It is thought that *Leucocytozoon* evolved from a parasite that spread through the orofaecal route and which infected intestinal wall. At some point parasites evolved the ability to infect the liver. This pattern is seen in the genus *Cryptosporidium*, to which *Plasmodium* is distantly related. At some later point this ancestor developed the ability to infect blood cell and to survive and infect mosquitoes. Once vector transmission was firmly established, the

Molecular evidence suggests that a reptile – specifically a squamte – was the first vertebrate host of *Plasmodium.* Birds were the second vertebrate hosts with mammals being the most

Leukocytes, hepatocytes and most spleen cells actively phagocytes particulate matter, which makes the parasite's entry into the cell easier. The mechanism of entry of *Plasmodium* species into erythrocytes is still very unclear, as it takes place in less than 30 seconds. It is not yet known if this mechanism evolved before mosquitoes became the main vectors for

The genus *Plasmodium* evolved (presumably from its *Leucocytozoon* ancestor) about 130 million years ago, a period that is coincidental with the rapid spread of the angiosperms (flowering plants). This expansion in the angiosperms is thought to be due to at least one gene duplication event. It seems probable that the increase in the number of flowers led to

Mosquitoes evolved in what is now South America about 230 million years ago. There are over 3500 species recognized, but to date their evolution has not been well worked out, so a number of gaps in our knowledge of the evolution of *Plasmodium* remain. There is evidence of a recent expansion of *Anopheles gambiae* and *Anopheles arabiensis* populations in the late

The reason why a relatively limited number of mosquitoes should be such successful vectors of multiple diseases is not yet known. It has been shown that, among the most common disease – spreading mosquitoes, the symbiont bacterium *Wolbachia* are not normally present. It has been shown that infection with *Wolbachia* can reduce the ability of some viruses and

*Plasmodium* belong to the family plasmodium, order Haemosporidia and phylum Apicomplexa. There are currently 450 recognized species in this order. Many species of this order are undergoing reexamination of their taxonomy with DNA analysis. It seems likely that many of these species will be re-assigned after these studies have been completed. For

an increase in the number of mosquitoes and their contact with vertebrates.[36]

*Plasmodium* to infect the mosquito, and that this effect is *Wolbachia*-strain specific.

previous orofecal route of transmission was lost.

recent group of vertebrates infected.

transmission of *Plasmodium*.[35]

Pleistocene in Nigeria.[37]

**16. Classification** 

Order Haemoporida

Family Haemoproteidae • Genus *Haemoproteus* • Subgenus *Parahaemoproteus*

this reason the entire order is outlined here.[38,39]

**Taxonomy** 


#### Family Leucocytozoidae


#### Family Plasmodiidae

	- Subgenus *Asiamoeba* Telford 1988
	- Subgenus *Bennettinia* Valkiunas 1997
	- Subgenus *Carinamoeba* Garnham 1996
	- Subgenus *Giovannolaia* Corradetti, Garnham & Laird 1963
	- Subgenus *Haemamoebe* Grassi & Feletti 1890
	- Subgenus *Huffia* Garnham & Laird 1963
	- Subgenus *Lucertaemoba* Telford 1988
	- Subgenus *Laverania* Bray 1963
	- Subgenus *Novyella* Corradtti, Garnham & Laird 1963
	- Subgenus *Ophidiella* Garnham 1966
	- Subgenus *Plasmodium* Bray 1963 emend, Garnham 1964
	- Subgenus *paraplasmodium* Telford 1988
	- Subgenus *Sauramoeba* Garnham 1966
	- Subgenus *Vinekeia* Garnham 1964

The eleven 'Asian' species included here form a clade with *P.* vivax being clearly closely related as are *P. knowsell* and *P. coatneyi;* similarly *P. brazilium* and *P. malaria* are related. *P. hylobati* and *P. inui* are closely related. *P. gonderi* appear to be more closely related to *P. vivax* than *P. malaria.*

*P. coatneyi* and *P. inui* appear to be closely related to *P. vivax.[38]* 

Biology of Malaria Parasites 21

The remaining groupings are based on the morphology of the parasites. Revision to this system are likely to occur in the future as more species are subject to analysis of their DNA. The four subgenera *Giovannolaia, Haemamoeba, Huffia* and *Novyella* were created by Corradetti *et al.* for the known avian malaria species. A fifth – *Bannettinia* – was created in 1997 by Valkiunas. The relationship between the subgenera are the matter of current investigation. Marinsen *et al.* 's recent (2006) paper outlines what is currently (2007) known. The subgenera *Haemamoeba, Huffia,* and *Bennettinia* appear to be monophyletic. *Novyella* appear to be well defined with occasional exceptions. The subgenus *Giovannolaia* need

*P. juxtanucleare* is currently (2007) the only known member of the subgenus *Bennettinia.*

*Nyssorhynchus* is an extinct subgenus of *Plasmodium.* It has one known member – *Plasmodium* 

Unlike the mammalian and bird malaria those species (more than 90 currently known) that

In 1966 Garnham classified those with large schizonts as *Sauramoeba,* those with small schizont as *Carinamoeba* and the single then known species infecting snakes *(Plasmodium wenyoni)* as Ophidiella. He was aware of the arbitrariness of this system and that it might not prove to be biologically valid. This scheme was used as the basis for the currently

These species have since been divided in to 8 genera –*Asiamoeba, Carinamoeba, Fallisia Garnia*, *Lacertamoeba,* and *Paraplasmodium* and *Sauramoeba.* Three of these genera *(Asiamoeba, Lacertamoeba* and *Plaraplasmodium)* were created by Telford in 1988. Another species *(Billbraya australis)* described in 1990 by Paperna and landau and is the only known species in this genus. This species may turn out to be another subgenus of lizard infecting

With the exception of *P. elongatum* the exoerythrocytic stage occur in the endothelial cells and those of the macrophage - lymphoid system. The exoerthrocytic stage of *P. elongatum*

The various subgenera are first distinguished on the basis of the morphology of the mature gametocytes. Those of subgenus *Haemamoeba* are round oval while those of the subgenera *Giovannolaia, Hiffia* and *Novyella* are elongated. These latter genera are distinguished on the basis of the size of the schizont: *Giovannolaia* and *Huffia* have large schizonts while those of

Species in the *subgenus Bennettinia* have the following characteristics:

Species in the subgenus *Giovannolaia* have the following characteristics:

**19. Bird infecting species** 

**20. Reptile infecting species** 

parasite the blood forming celss.

The type species is *Plasmodium juxtanucleare.* 

*Novyella* are small.[52]

infect reptiles have been more difficult to classify.

revision.[49,50]

*dominium*[51].

accepted system.[52]

*Plasmodium.*

*P. ovale* is more closely related to *P. malaria* than to *P. vivax.*

Within the 'Asian' clade are three unnamed potential species. One infect each of the two chimpanzee subspecies included in the study *(Pan troglodytes troglodytes* and *pan troglodytes schweinfurthii).* These appear to be related to the *P. vivax P. simium* clade.

Two unnamed potential species infect the bonbo *(Pan paniscus)* and these are related to the *P. malaria P. brazillium* calde.
