Polychromophilus murinus are obligate intracellular parasites that infect Vespertilionid bats. The parasite is transmitted via several species of Nyceribiidae (vector). "P. murinus" plays a malarial-like role in a variety of Vespertillionid bat species, with a wide geological distribution. It follows a typical haemosporidian life cycle, with mature gametocytes of the parasite taking over the bat hosts red blood cells as the key sign of infection. "P. murinus" is recorded in Europe, Asia, and Madagascar, and one recording in Panama. There are no climatic or seasonal variables in relation to infection, but has sporadic periods of infection intensity in bat species. There is not a large or known pathogenic effect on the bat host; while it does burst red blood cells, there is a lower degree of infection compared to other malarial species, so it does not cause anemia. Fever is a possible sign of pathology, but since bats are heterotherms, it is argued whether fever is possible. Overall, there is no form of pathology agreed upon caused by "P. murinus" and no current treatment. 
Phylogenetics / taxonomy.
"Polychromophilus" parasites are a monophyletic clade with two genetically distinct subclades, "P. melanipherus", and "P. murinus". Chumnandee et al. quote previous works on other distinct subclades under "Polychromophilus: P. adami, P. corradetti," and "P. deanei." It should be noted however that these three species have limited and dated information. Another study on these three species by Rasoanoro et al. shows "Polychromophilus" sp. parasites in a range of bat hosts, while there were several unidentified genetically distinct species under the genus, a connection to "P. adami, P. corradetti", or "P. deanei" was not noted. 
"Polychromophilus's" most recent common ancestor is the avian/reptilian "Plasmodium", showing a distant relationship between "Polychromophilus" to "Plasmodium" and mammalian "Hepatocystis".
"Polychromophilus murinus" is one genus under many of the family Plasmodiidae, which consists of five species: 
Hosts / vectors.
Bats.
"Polychromophilus murinus" is reported to infect the family Vespertilionidae. The bat species below are recorded across different studies of where "P. murinus" was found, within different geological contexts. 
Species found with infection.
"Eptesicus serotinus", "Kerivoula hardwickii", "Laephotis capensis", "Myotis bechsteinii", "Myotis blythii", "Myotis crypticus", "Myotis daubentonii", "Myotis goudoti", "Myotis Myotis", "Myotis nattereri", "Myotis nigricans" ", Myotis siligorensis", "Neoromicia grandidieri", "Nyctalus noctula", "Scotophilus robustus", "Vespertilio murinus" 
Bat flies.
The family Nyceribiidae are wingless, permanent, obligate ectoparasitic bat flies. Bat flies are vectors for "Polychromophilus" parasites. Various species of Nyceribiidae are highly host-specific, although some infect multiple bat hosts, observations show a small amount of non-primary host infections. The bat flies listed below have been found to carry "P. murinus" to bat hosts, these species of bat fly can carry other "Polychromophilus" species as well. 
Species found with infection.
"Basilia nana", "Basilia nattereri" ", Nycteribia kolenatti" ", Nycteribia latreilii" ", Nycrteribia pediculuaria" ", Nycteribia vexata" ", Nycteribia schmidtlii", "Penicillidia dufourii" 
Bat fly reproduction in relation to bats.
Bat flies reproduce via viviparious puparity, the female bat flies lay the final larval stage onto the roost wall, and this 3rd instar larvae will develop into a puparium quickly, followed by three to four weeks of pupal development. The now-adult bat fly will exit the chrysalis when it senses a juvenile bat host nearby, introducing "Polychromophilus murinus" at early development.
Life cycle.
The Nycterbiidae species carry "Polychromophilus murinus" sporozoites through the salivary glands until they get a blood meal from the bat host. The sporozoites are then injected into the bat host while blood-feeding; in the host schizogony occurs in various organs (exo-erythrocytic) of the reticuloendothelial system. This results in merozoites being released, that then invade erythrocytes, developing into sexual gametocytes when in the red blood cells, a key sign of infection by "P. murinus" "." These gametocytes are taken back up by the bat fly, which then under-go sexual reproduction (gametogony), producing an oocyst, which will then develop sporozoites on the gut wall of the vector. Effectively restarting the life cycle, these sporozoites will migrate to the salivary glands, then to a bat host during feeding.
Vertical transmission of "Polychromophilus murinus" does not take place in either bat fly puparia or bat pups. Rather, it is exclusively directly transmitted from the bat flies blood feeding. 
Cell structure.
Gametocytes are large round to oval-shaped with a maximal diameter of 6-8 μm. Mature gametocytes within the bat host will take up majority of the red blood cell space, leaving only the edge of the red blood cell visible. Pigmentation granules are of similar shape to mouse droppings and are of irregular size and amount, typically occurring in clusters. Like many genuses under Plasmodiidae, there are hemozoin pigment grains which are scattered within the cytoplasm. On average between 14 - 25 dark pigments are in the cytoplasm. Female macrogametocytes have a round and well-bordered nucleus in a dense cytoplasm, while male microgametocytes are more oval-shaped with a lighter colored cytoplasm, and a diffuse, random, ill-defined nucleus; a distingushing characteristic of male microgametocytes of "P. murinus". 
Distribution.
"Polychromophilus murinus" has a sporadic infection rate, meaning there are unsteady increases and flat trends across different years and seasons. The most notable infection rates studied were during July - August of 2010, with a period of increase over the summer season, but this trend did not continue the next year. "P. murinus" infections have been recorded across Europe, Asia, Madagascar, and Panama.
Geological prevalence.
"Polychromophilus murinus" is geologically prevalent in Europe, Asia, Madagascar, and one recording in Panama. The parasite shows very little phylogeographical structure, due to its broad dispersal. Since there is a larger distribution in Europe of "P. murinus", there are a far greater number of bats to have been infected in this geological range than compared to Asia, Madagascar, or Panama.
European countries recorded with infection: Belgium, Bulgaria, France, Georgia, Germany, Hungary, Italy, Luxembourg, Netherlands, Romania, Russia, Slovenia, Spain, Switzerland, Turkey, the United Kingdom, Ukraine.
Bat species recorded in Europe with "P. murinus:"
Bat fly species recorded in Europe with "P. murinus": 
Asian countries recorded with infection : Cambodia, Thailand
Bat species recorded in Asia with "P. murinus":
Bat fly species recorded in Asia with "P. murinus":
Madagascar and Panama
In Madagascar, the recorded bat species that has been infected with "P. murinus" are "Myotis goudoti" and "Scotophilus robustus," both infected by Nycteribiid flies. Within Panama, there one bat species recorded to have been infected; "Myotis nigricans" by a Nycteribiid fly. 
Susceptibility.
As the bat hosts and bat fly vectors reproduce nearby each other in the roosts, there is a high level of exposure of "Polychromophilus murinus", especially with the young bat pups, as the bat fly adults primarily target them. This continues the "P. murinus" life cycle establishing infection in newly emerging bat flies, but with targeting of young bat pups, there is an increasing tolerance over time to further infections. Observed by the absence of pathological symptoms in adults in conjunction with the parasites' ability to remain in bat populations throughout the year. The parasite easily remains in bat populations as bat flies are long-lived insects and capable of overwintering while maintaining a "P. murinus" infection. On this note, luckily, cross and co-infections between "Polychromophilus sp." in the same bat host has not been recorded.
Biological prevalence.
There is no observed difference in effect or prevalence between the sexes of bat hosts, but, the condition and age of the bat hosts seem to have a correlation with parasitemia. Adult bats had an increased rate of infection with increasing body condition, while juvenile bats had a strong negative relationship with body condition and parasitemia. Bat hosts with lower body conditions had higher parasitemia, meaning that juvenile bats hold a higher chance of parasitemia and a higher infection load than adult bats. 
Pathology.
Effect / symptoms.
The physiological effect of infection found to be caused by "Polychromophilus murinus" has only been found to be weight loss, with debate over fever, as bats are heterotherms. Since there is no asexual multiplication (erythrocytic schizogony) occurring in the bat host, the erythrocytes destroyed by "P. murinus" during an infection are lower compared to other malarial species. Meaning, the bat hosts do not experience anemia unless undergoing an extreme case of infection. Due, however, to the little research done in this area of pathology and "P. murinus's" appearances being ubiquitous, it is hard to state that the parasite is unknown if it is detrimental, beneficial, or neutral in its infection. 
"Polychromophilus murinus" in relation to humans.
"Polychromophilus murinus" is not zoonotic, and is not considered to have any effect on humans. There has been an attempt in studying "P. murinus" infection on humans by injecting infected bat blood into a human subject and while a fever developed, it is thought that it was due to contamination from the injection and surrounding pathogens.
Treatment.
There is no known treatment for "P. murinus".