Plasmodium hermani
Encyclopedia
Plasmodium hermani is a parasite of the genus Plasmodium
subgenus Huffia
.
Like all Plasmodium species P. hermani has both vertebrate
and insect
hosts. The vertebrate hosts for this parasite are bird
s.
The presence and degree of pigmentation vary with maturity of the host cell. Host cell nuclei may be displaced, but are not distorted, except slightly by pressure from the parasite. The asexual stages parasitize all cells in the erythrocyte series. In heavy infections the parasites occur predominantly in erythroblasts and their precursors.
Schizonts are rounded with 6–14 nuclei arranged peripherally as a rosette. Infected cells are often rounded and enlarged.
Gametocytes are elongate and slender with irregular margins and are found exclusively in erythrocytes. The pigment is dispersed in black granules throughout the cytoplasm. The host cells may be somewhat distorted in shape by lateral hypertrophy.
by
Mature gametocytes of P. durae also exhibits the following characteristics which are not found those of P. hermani
Plasmodium hermani resembles Plasmodium elongatum in
It can be distinguished from Plasmodium elongatum by
Note: Cx. nigripalpus appears to be the main natural vector.
Infection of turkeys causes anaemia, splenomegaly and decreased growth but is not normally fatal.
Plasmodium
Plasmodium is a genus of parasitic protists. Infection by these organisms is known as malaria. The genus Plasmodium was described in 1885 by Ettore Marchiafava and Angelo Celli. Currently over 200 species of this genus are recognized and new species continue to be described.Of the over 200 known...
subgenus Huffia
Huffia
Huffia is a subgenus of the genus Plasmodium - all of which are parasitic protozoa. The subgenus was created in 1963 by Corradetti et al....
.
Like all Plasmodium species P. hermani has both vertebrate
Vertebrate
Vertebrates are animals that are members of the subphylum Vertebrata . Vertebrates are the largest group of chordates, with currently about 58,000 species described. Vertebrates include the jawless fishes, bony fishes, sharks and rays, amphibians, reptiles, mammals, and birds...
and insect
Insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...
hosts. The vertebrate hosts for this parasite are bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
s.
Description
This species was first described in 1975 by Telford and Forrester in a wild turkeyThe presence and degree of pigmentation vary with maturity of the host cell. Host cell nuclei may be displaced, but are not distorted, except slightly by pressure from the parasite. The asexual stages parasitize all cells in the erythrocyte series. In heavy infections the parasites occur predominantly in erythroblasts and their precursors.
Schizonts are rounded with 6–14 nuclei arranged peripherally as a rosette. Infected cells are often rounded and enlarged.
Gametocytes are elongate and slender with irregular margins and are found exclusively in erythrocytes. The pigment is dispersed in black granules throughout the cytoplasm. The host cells may be somewhat distorted in shape by lateral hypertrophy.
Differential diagnosis
Plasmodium hermani can be distinguished from Plasmodium duraePlasmodium durae
Plasmodium durae is a parasite of the genus Plasmodium subgenus Giovannolaia.Like all Plasmodium species P. durae has both vertebrate and insect hosts...
by
- low level (< 6%) parasitemia
- nonlethal in turkey poults
- absence of phanerozoites in capillary endothelium of the brainBrainThe brain is the center of the nervous system in all vertebrate and most invertebrate animals—only a few primitive invertebrates such as sponges, jellyfish, sea squirts and starfishes do not have one. It is located in the head, usually close to primary sensory apparatus such as vision, hearing,...
and viscera - inability to infect chicks (Gallus domesticus)
Mature gametocytes of P. durae also exhibits the following characteristics which are not found those of P. hermani
- tend to lie obliquely within the host cell
- displace the nucleus to one pole of the cell
- possess one or more clumps of clear pigment granules
Plasmodium hermani resembles Plasmodium elongatum in
- schizogony in all types of erythrocyte precursors
- concentration of schizonts in heavy infections in bone marrow and spleen
- gametocyte morphology
- gametocytes occurring in erythrocytes only
It can be distinguished from Plasmodium elongatum by
- its lack of infectivity to passeriform and anseriform hosts
- by the strong immune response which develops in infected birds
Vectors
- Culex nigripalpus
- Culex restuans
- Culex salinarius
- Wyeomyia vanduzeei
Note: Cx. nigripalpus appears to be the main natural vector.
Clinical features and host pathology
This species infects knots (Calidris canutus), bobwhites (Colinus virginianus) and turkeys (Meleagris gallopavo).Infection of turkeys causes anaemia, splenomegaly and decreased growth but is not normally fatal.