''Nosopsyllus fasciatus'', the northern rat flea, is a species of

flea Flea, the common name for the order (biology), order Siphonaptera, includes 2,500 species of small flightless insects that live as external parasites of mammals and birds. Fleas live by hematophagy, ingesting the blood of their hosts. Adult f ...

found on domestic rats and house mice. Northern rat fleas are external parasites, living by

hematophagy Hematophagy (sometimes spelled haematophagy or hematophagia) is the practice by certain animals of feeding on blood (from the Greek words αἷμα ' "blood" and φαγεῖν ' "to eat"). Since blood is a fluid tissue rich in nutritious ...

off the

blood Blood is a body fluid in the circulatory system of humans and other vertebrates that delivers necessary substances such as nutrients and oxygen to the cells, and transports metabolic waste products away from those same cells. Blood is com ...

rodent Rodents (from Latin , 'to gnaw') are mammals of the Order (biology), order Rodentia ( ), which are characterized by a single pair of continuously growing incisors in each of the upper and Mandible, lower jaws. About 40% of all mammal specie ...

s. ''N. fasciatus'' can bite humans, but they are more common parasites of rodents.Zurita, A., Callejon, R., de Rojas, M. and Cutillas, C.. 2017. Morphological and molecular study of the genus ''Nosopsyllus'' (Siphonaptera: Ceratophyllidae). ''Nosopsyllus barbarus'' (Jordan & Rothschild 1912) as a junior synonym of ''Nosopsyllus fasciatus'' (Bosc d’Antic, 1800). Insect Systematics & Evolution. 49(1): pp.81-101. Since ''N. fasciatus'' carries the agents responsible for plague and marine typhus and can bite humans, making the species of one of concern for people. Diseases that can be spread through fleas include the plague and

typhus Typhus, also known as typhus fever, is a group of infectious diseases that include epidemic typhus, scrub typhus, and murine typhus. Common symptoms include fever, headache, and a rash. Typically these begin one to two weeks after exposu ...

. The rat flea is widespread due to their relationship to rodents and other vertebrates. They can be found co-infecting their host with other parasites. It is the most widely spread of its genus, having originated in Europe, but has been transported to temperate regions worldwide. The genus, ''Nosopsyllus'', contains sixty-eight

taxa In biology, a taxon (back-formation from ''taxonomy''; : taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular name and ...

, which is then divided into four categories ''Nosopsyllus'', ''Gerbillophilus'', ''Nosinius'', and ''Penicus''.

Identification

''N. fasciatus'' characteristically look similar to other ''Nosopsyllus'' species. Like others of this genus, this species is laterally flattened, has well-developed eyes, and a rounded head. ''N. fasciatus'' has an elongated body, 3 to 4 mm in length. It has six posterior and six anterior head bristles containing three long and three short bristles. A distinguishing feature is that the dorsal bristle in the posterior row on the head is long but there is a characteristic short bristle immediately ventral to the dorsal bristle.

Distribution

''N. fasciatus'' is

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

to Europe but has a worldwide distribution because of their dependence on rodents and other

mammals A mammal () is a vertebrate animal of the class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three middle e ...

for survival.>Crooks, K.R., Garcelon, D.K., Scott, C.A., Depue, J.E., Wilcox, J.T., Kimsey, R.B. and Van Vuren, D.H.. 2004. Ectoparasites of a threatened insular endemic mammalian carnivore: the island spotted skunk. The American midland naturalist. 151(1): pp.35-41. The genus, ''Nosopsyllus'', is native to the

Palearctic Realm The Palearctic or Palaearctic is a biogeographic realm of the Earth, the largest of eight. Confined almost entirely to the Eastern Hemisphere, it stretches across Europe and Asia, north of the foothills of the Himalayas, and North Africa. The ...

but has spread through human transportation to other regions of the world. The cause of this human-facilitated spread of ''N. fasciatus'' was most likely due to the globalization of trade. Other areas populated by ''N. fasciatus'' are the United States, including some islands that have been spread from the mainland.Schwan, T.G.. 1984. ''Nosopsyllus fasciatus'' parasitizing house mice on southeast Farallon Island. California (Siphonaptera: Ceratophyllidae). Pan-Pac. Entomol. 60: pp.345-349. The cause of the spread is due to rats escaping from the mainland to the island through boats. The islands such as the San Miguel Island and

Hawaii Hawaii ( ; ) is an island U.S. state, state of the United States, in the Pacific Ocean about southwest of the U.S. mainland. One of the two Non-contiguous United States, non-contiguous U.S. states (along with Alaska), it is the only sta ...

have been inhabited by rats that carry this species. ''N. fasciatus'' is successful in spreading to new areas because it is a generalist and can colonize a new area and adapt easily.

Anatomy

The rat flea has three

instar An instar (, from the Latin '' īnstar'' 'form, likeness') is a developmental stage of arthropods, such as insects, which occurs between each moult (''ecdysis'') until sexual maturity is reached. Arthropods must shed the exoskeleton in order to ...

stages in its development.>Elbel, R.E.. 1951. Comparative studies on the larvae of certain species of fleas (Siphonaptera). The Journal of Parasitology. 37(2): pp.119-128. The flea larva has two

pharynx The pharynx (: pharynges) is the part of the throat behind the human mouth, mouth and nasal cavity, and above the esophagus and trachea (the tubes going down to the stomach and the lungs respectively). It is found in vertebrates and invertebrates ...

chambers, where the posterior one is important for suction.Sharif, M.. 1937. VII-On the internal anatomy of the larva of the Rat-flea, ''Nosopsyllus fasciatus'' (Bosc). Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences. 227(547): pp.465-538. After each

moulting In biology, moulting (British English), or molting (American English), also known as sloughing, shedding, or in many invertebrates, ecdysis, is a process by which an animal casts off parts of its body to serve some beneficial purpose, either at ...

period, there is a cost of partial replacement of digestive cells for the new regenerative cells produced during this period. The larva has a two-chambered poorly-developed heart with a dorsal blood vessel.

Larval Feeding Behaviour

Larval ''N. fasciatus'' feed on adult fleas through attachment or on injured individuals.Molyneux, D.H.. 1967. Feeding Behaviour of the Larval Rat Flea ''Nosopsyllus fasciatus'' Bosc. Nature. 215(5102): pp.779-779. In the nest, larval fleas are observed to remain near adults in the debris. Larvae will attach to the posterior end of adults with their mandibles (insect mouthpart). The larva receives nutrients when the adult defecates, which contains blood within the fecal matter. The blood meal is ingested by a sucking action performed by the larvae. If the cuticle of the adult has been injured, the larvae can attack and eat the body of the injured adult. This behaviour categorizes ''N. fasciatus'' larvae as semi-predatory and displays opportunist cannibalism behaviour.

Pathology

Though the northern rat flea primarily parasitizes the Norway rat, ''Rattus norvegicus'', it has occasionally been observed feeding on humans and wild rodents. It is a vector for plague and is known to be a host of the rat tapeworm ''Hymenolepis diminuta'' in

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...

Europe Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...

, and

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

. Rodents acts as the primary host for flea species and parasitized rodents account for 25% of all mammals.

Effect on Flea

Plague transmission causes a blockage in the stomach of ''N. fasciatus''.Eskey, C.R., Prince, F.M. and Fuller, F.B.. 1951. Double infection of the rat fleas ''X. cheopis'' and ''N. fasciatus'' with Pasteurella and Salmonella. Public Health Reports. (1896-1970): pp.1318-1326. This blockage is caused by a mass formation in the proventriculus. However, a study revealed that a simultaneous ''

Salmonella ''Salmonella'' is a genus of bacillus (shape), rod-shaped, (bacillus) Gram-negative bacteria of the family Enterobacteriaceae. The two known species of ''Salmonella'' are ''Salmonella enterica'' and ''Salmonella bongori''. ''S. enterica'' ...

'' infection inhibits the formation of this blockage. However, fleas simultaneously infected by the plague and ''Salmonella'' died within 2-3 days due to bloody diarrhea.Eskey, C.R., Prince, F.M. and Fuller, F.B.. 1949. Transmission of ''Salmonella enteritidis'' by the rat fleas ''Xenopsylla cheopis'' and ''Nosopsyllus fasciatus''. Public Health Reports. 64(30): pp.933-941.

Effect on Host

Parasites are known to reduce the fitness of their host.Devevey, G. and Christe, P.. 2009. Flea infestation reduces the life span of the common vole. Parasitology. 136(11): pp.1351-1355. Therefore, parasitism by fleas can affect the population of the hosts. Studies in gerbil hosts have found that flea infestation reduced ''Gerbillus dasyurus'' body mass and immune defences. In common vole hosts, it has also been found that flea infestation reduces body mass and immune defences and also induces an iron deficiency. These effects on the host negatively impact survivability and population density.

Disease Vectors

Like other fleas, this species plays a role in spreading zoonotic diseases.Herrero-Cófreces, S., Flechoso, M.F., Rodríguez-Pastor, R., Luque-Larena, J.J. and Mougeot, F.. 2021. Patterns of flea infestation in rodents and insectivores from intensified agro-ecosystems, Northwest Spain. Parasites & Vectors. 14(1): pp.1-13. Rise in rodent outbreaks of zoonotic diseases can spread to humans, like the plague, rickettsioses, and bartonelloses. They can also transmit pathogens that cause tularemia, Q fever, trypanosomiasis, and myxomatosis. The rat flea contributes to the reemergence and cycles of some diseases, as previously mentioned. Infestation is more prevalent during the summer months and drops through the winter months. The highest infestation rate occurs during the summer because of increased activity in the mammal hosts that help spread the fleas and their disease vectors.

Gallery

File:Nosopsyllus fasciatus.jpg, A female and male rat flea ''N. fasciatus'' File:NHMUK010177300 A rat flea - Nosopsyllus Nosopsyllus fasciatus (Bosc, 1800).jpg, Close-up of a female slide-mounted ''N. fasciatus''

References

{{Taxonbar, from=Q7059249 Ceratophyllidae Parasites of rodents Insects of Europe