Nosema apis
Encyclopedia
Nosema apis is a microsporidia
n, a small, unicellular parasite that mainly affects honey bee
s. It causes nosemosis, also called nosema, which is the most widespread of adult honey bee diseases. The dormant stage of Nosema apis is a long lived spore
which is resistant to temperature extremes and dehydration and cannot be killed by freezing the contaminated comb. Nosemosis is a listed disease with the Office International des Epizooties
(OIE).
, which are now classified as fungi or fungi-related. Nosema apis has a resistant spore that withstands temperature extremes and dehydration. In 1996, a similar microsporidian parasite of the eastern honey bee
(Apis cerana) was discovered in Asia, which was named Nosema ceranae
. There is little known about the symptoms and the course of the disease.
Chinese researchers found Nosema ceranae in spring 2005 in Taiwan
for the first time, and it has now been seen on Western honey bees. Spanish bee researchers (Higes et al.) reported that the new pathogen was discovered in 2005 in Spain
and was observed to have a notably higher virulence than the western version. The disease caused by Nosema ceranae in Western honey bees in Spain is related to heavier disease patterns deviating from the previously typical findings (unusually heavy intestine injuries in the bees, no diarrhea
, preferential affliction of older collecting bees. Bees die far away from the dwellings, as when they leave they are too weak to return. This leads to collapse of the bee colony). It was observed within a few years that there had been a strongly increased propagation of Nosema and their occurrence was happening all year round due to the higher resistance of Nosema ceranae. A higher reinfection rate of the bee colonies is assumed, since the pathogen survives longer in the external environment.
The two pathogen types cannot be differentiated with usual routine investigations, but can be distinguished only with the assistance of molecular-genetic methods such as polymerase chain reaction
.
Spanish researchers regard with alarm the insurgence of Nosema ceranae in Spain, which has now replaced Nosema apis. Because of this newly emergent parasite, the pathogen is assumed to be related to the substantial bee mortality observed in Spain since autumn 2004. They conjecture a similar cause of increased bee colony losses reported in other European countries, such as those expreinced in France
since end of the 1990s and in Germany
in 2002 and 2003.
In the samples of examined in German laboratories in the winter of 2005/2006, the new pathogen was present in eight of ten examined bee hives examined (CVUA Freiburg), with the distribution varying from state to state. The bees with the classical pathogen Nosema apis came from Thuringia
and Bavaria
, whereas Nosema ceranae prevailed in Baden-Wuerttemberg, Bavaria and North Rhine-Westphalia
. There were also reports from Switzerland
(July 2006) and from several regions of Italy
(September 2006) where Nosema ceranae were found in bee colonies with increased mortality.
German scientists ask themselves whether Nosema ceranae was already present in Europe and simply had not yet been differentiated Nosema apis. It is possible the current disease processes are more extreme when a Nosema affliction occurs because the colonies are already weakened by the Varroa mite or other factors that make them more susceptible. There are however signs that the disease process of Nosema has changed, and that the disease arises now all year round.
The investigation of 131 bee colonies from Bavaria within the framework of a dissertation supports the thesis of a causal participation between bee viruses, which were transferred by arthropod
s (for instance the Varroa mite), and the periodically arising mass losses of life in the hives. Since only comparatively few of these colonies were afflicted with microsporidians (evidence showed 14.5% of the cases were afflicted with microsporidian spores, with half of the cases by Nosema apis and/or Nosema ceranae), a correlation between microsporidian affliction and virus infection could not be determined. The question of whether the colonies were dying rather from the "new" version of Nosema, which (possibly) possesses a higher pathogenicity, or due to virus diseases connected with varroa affliction, is internationally controversially continued to be discussed among scientists and beekeepers.
. It arises mostly in the spring after periods of bad weather, although it may also be a winter disease that is only noticed in the spring when beekeepers first inspect their hives. The female worker bees are most strongly afflicted, less so the drones. The queen bee is rarely infected since afflicted bees rarely participate in feeding the queen. The most notable symptom is dysentery
. This appears as yellow stripes on the outside of the hive and in severe cases, inside the hive. Bees may be unable to fly ("crawling") due to disjointed wings.
Further symptoms include increased girth of the abdomen, missing sting reflex, and early supersedure of the queen. If the queen is infected, her ovaries degenerate and ovum production drops due to atrophy of the ova, after which she is likely to be superseded. The disease pattern described by Higes et al.. in Spain for Nosema ceranae is slightly different than with Nosema apis. The changes in the digestive system were substantially more serious than with Nosema apis, related to particularly heavy and spacious cell lesions. On the other hand, classical symptoms were missing from Nosema ceranae, such as diarrhea, crawling, large numbers of dead bees in the apiary etc. Bees tend to die away from the apiary, which causes a reduction in food gathered and can eventually lead to colony collapse. Ritter (CVUA Freiburg) reports symptoms can arise throughout the year from Nosema ceranae, in contrast to Nosema apis. In the winter some colonies died within a short time and the bees lay dead in the box (in Spain, hives usually remained empty). Whether these features are related to the new form of Nosema cannot be conclusively proven.
, and the epithelial cells of the ventriculus are infected when the vegetative stage is introduced by way of the hollow polar filament
. Once inside a cell, the vegetative stage increases in size and multiplies, effecting an apparent concurrent reduction of RNA synthesis in the host cell. In 6–10 days the infected host epithelial cell becomes filled with new spores. Epithelial cells are normally shed into the ventriculus where they burst – releasing digestive enzyme
s. When infected cells are shed similarly, they release 30–50 million infective spores when they burst.
of the oocyte
s. Queens that become infected by the parasite during the brood rearing season are superseded by the bees.
The seasonal trend of typical infections exhibits low levels during summer, a small peak in autumn, and a slow rise of infection during winter. It is more common during times of confinement like winter and spring. In the spring the level of infection increases rapidly as brood rearing starts and while flight possibilities are still limited. Colonies in northern climates are more seriously affected than colonies in the south because of the increased amount of time bees are confined in the hive. Nosema, if left untreated, can cause queen supersedure, winter kills, reduced honey yields, and dwindling populations.
or on PCR analysis of infected tissue. No specific outward sign of disease may be present, although in dissection
s the ventriculus
often appears whitish and swollen in late stages of infection. The disease is easily detected in samples of whole bees macerated in water. The fluid is examined under a light microscope at 250–500 x magnification where the characteristic Nosema spores can be observed. Though the spores of N. apis and N. ceranae have slight morphological and ultrastructural differences, they cannot be reliably differentiated via light microscopy. PCR analysis or electron microscopy of spores are the only reliable ways to differentiate between the two types of Nosema infection, given genetic variation and variation in the number of sporular polar filament
coils between the two species.
, the causative agent of Stone Brood) inhibits the spores reproducing in the ventriculus, but does not kill the spores. A disinfection of the honeycombs and utensils is recommended for an extensive disease outbreak.
The spores are sensitive to chemicals such as acetic acid
and Formalin, and physical radiation: ultrasonic
and gamma radiation. A natural treatment product called Protofil, made of plant extractions, vitamins, and microelements, was presented at the International Federation of Beekeepers' Association – Apimondia 2004 as a preventative remedy. Other possible natural treatments include HoneyBHealthy, ApiHerb, Vita Feed Gold, Vitafeed Green, Nozevit, and possibly thymol.
Heat treatment in 49 °C (120.2 °F) for 24 hours can be used to kill the spores on contaminated equipment.
), Nosema trichoplusiae (moth Trichoplusia ni), Nosema furnacalis (Ostrinia furnacalis), Nosema necatrix (cutworm moth Mythimna unipuncta
), Nosema locustae (grasshoppers
) and Nosema pyrrhocoridis (Firebug
).
The mark craze (Pébrine disease), caused by Nosema bombycis is one of the most important parasitic diseases of the silk moth.
Other pathogens similar to Nosema cause diseases in mammals. In veterinary practice the term "Nosema" is sometimes used to refer to Encephalitozoonosis
, a disease common in rabbits, in which the brain is infected with the intracellular parasitic microsporidian Encephalitozoon cuniculi
. The term arises from the fact that encephalitozoon were formerly classified as members of the genus Nosema.
Microsporidia
The microsporidia constitute a phylum of spore-forming unicellular parasites. They were once thought to be protists but are now known to be fungi. Loosely 1500 of the probably more than one million species are named now. Microsporidia are restricted to animal hosts, and all major groups of animals...
n, a small, unicellular parasite that mainly affects honey bee
Honey bee
Honey bees are a subset of bees in the genus Apis, primarily distinguished by the production and storage of honey and the construction of perennial, colonial nests out of wax. Honey bees are the only extant members of the tribe Apini, all in the genus Apis...
s. It causes nosemosis, also called nosema, which is the most widespread of adult honey bee diseases. The dormant stage of Nosema apis is a long lived spore
Spore
In biology, a spore is a reproductive structure that is adapted for dispersal and surviving for extended periods of time in unfavorable conditions. Spores form part of the life cycles of many bacteria, plants, algae, fungi and some protozoa. According to scientist Dr...
which is resistant to temperature extremes and dehydration and cannot be killed by freezing the contaminated comb. Nosemosis is a listed disease with the Office International des Epizooties
Office international des épizooties
The World Organisation for Animal Health is the intergovernmental organisation responsible for improving animal health worldwide and was created by an international agreement as the International Office of Epizootics on 25 January 1924...
(OIE).
Pathogen
Until recently Nosema apis had been considered to be a single-celled protozoan pathogen of the Western honey bee (Apis mellifera). Nosema apis is a unicellular parasite of the class MicrosporidiaMicrosporidia
The microsporidia constitute a phylum of spore-forming unicellular parasites. They were once thought to be protists but are now known to be fungi. Loosely 1500 of the probably more than one million species are named now. Microsporidia are restricted to animal hosts, and all major groups of animals...
, which are now classified as fungi or fungi-related. Nosema apis has a resistant spore that withstands temperature extremes and dehydration. In 1996, a similar microsporidian parasite of the eastern honey bee
Apis cerana
Apis cerana, or the Asiatic honey bee , is a species of honey bee found in southern and southeastern Asia, such as China, India, Japan, Malaysia, Nepal, Bangladesh and Papua New Guinea. This species is the sister species of Apis koschevnikovi, and both are in the same subgenus as the Western honey...
(Apis cerana) was discovered in Asia, which was named Nosema ceranae
Nosema ceranae
Nosema ceranae is a microsporidian, a small, unicellular parasite that mainly affects Apis cerana, the Asiatic honey bee. It may cause nosemosis, also called nosema...
. There is little known about the symptoms and the course of the disease.
Chinese researchers found Nosema ceranae in spring 2005 in Taiwan
Taiwan
Taiwan , also known, especially in the past, as Formosa , is the largest island of the same-named island group of East Asia in the western Pacific Ocean and located off the southeastern coast of mainland China. The island forms over 99% of the current territory of the Republic of China following...
for the first time, and it has now been seen on Western honey bees. Spanish bee researchers (Higes et al.) reported that the new pathogen was discovered in 2005 in Spain
Spain
Spain , officially the Kingdom of Spain languages]] under the European Charter for Regional or Minority Languages. In each of these, Spain's official name is as follows:;;;;;;), is a country and member state of the European Union located in southwestern Europe on the Iberian Peninsula...
and was observed to have a notably higher virulence than the western version. The disease caused by Nosema ceranae in Western honey bees in Spain is related to heavier disease patterns deviating from the previously typical findings (unusually heavy intestine injuries in the bees, no diarrhea
Diarrhea
Diarrhea , also spelled diarrhoea, is the condition of having three or more loose or liquid bowel movements per day. It is a common cause of death in developing countries and the second most common cause of infant deaths worldwide. The loss of fluids through diarrhea can cause dehydration and...
, preferential affliction of older collecting bees. Bees die far away from the dwellings, as when they leave they are too weak to return. This leads to collapse of the bee colony). It was observed within a few years that there had been a strongly increased propagation of Nosema and their occurrence was happening all year round due to the higher resistance of Nosema ceranae. A higher reinfection rate of the bee colonies is assumed, since the pathogen survives longer in the external environment.
The two pathogen types cannot be differentiated with usual routine investigations, but can be distinguished only with the assistance of molecular-genetic methods such as polymerase chain reaction
Polymerase chain reaction
The polymerase chain reaction is a scientific technique in molecular biology to amplify a single or a few copies of a piece of DNA across several orders of magnitude, generating thousands to millions of copies of a particular DNA sequence....
.
Spanish researchers regard with alarm the insurgence of Nosema ceranae in Spain, which has now replaced Nosema apis. Because of this newly emergent parasite, the pathogen is assumed to be related to the substantial bee mortality observed in Spain since autumn 2004. They conjecture a similar cause of increased bee colony losses reported in other European countries, such as those expreinced in France
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
since end of the 1990s and in Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
in 2002 and 2003.
In the samples of examined in German laboratories in the winter of 2005/2006, the new pathogen was present in eight of ten examined bee hives examined (CVUA Freiburg), with the distribution varying from state to state. The bees with the classical pathogen Nosema apis came from Thuringia
Thuringia
The Free State of Thuringia is a state of Germany, located in the central part of the country.It has an area of and 2.29 million inhabitants, making it the sixth smallest by area and the fifth smallest by population of Germany's sixteen states....
and Bavaria
Bavaria
Bavaria, formally the Free State of Bavaria is a state of Germany, located in the southeast of Germany. With an area of , it is the largest state by area, forming almost 20% of the total land area of Germany...
, whereas Nosema ceranae prevailed in Baden-Wuerttemberg, Bavaria and North Rhine-Westphalia
North Rhine-Westphalia
North Rhine-Westphalia is the most populous state of Germany, with four of the country's ten largest cities. The state was formed in 1946 as a merger of the northern Rhineland and Westphalia, both formerly part of Prussia. Its capital is Düsseldorf. The state is currently run by a coalition of the...
. There were also reports from Switzerland
Switzerland
Switzerland name of one of the Swiss cantons. ; ; ; or ), in its full name the Swiss Confederation , is a federal republic consisting of 26 cantons, with Bern as the seat of the federal authorities. The country is situated in Western Europe,Or Central Europe depending on the definition....
(July 2006) and from several regions of Italy
Italy
Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...
(September 2006) where Nosema ceranae were found in bee colonies with increased mortality.
German scientists ask themselves whether Nosema ceranae was already present in Europe and simply had not yet been differentiated Nosema apis. It is possible the current disease processes are more extreme when a Nosema affliction occurs because the colonies are already weakened by the Varroa mite or other factors that make them more susceptible. There are however signs that the disease process of Nosema has changed, and that the disease arises now all year round.
The investigation of 131 bee colonies from Bavaria within the framework of a dissertation supports the thesis of a causal participation between bee viruses, which were transferred by arthropod
Arthropod
An arthropod is an invertebrate animal having an exoskeleton , a segmented body, and jointed appendages. Arthropods are members of the phylum Arthropoda , and include the insects, arachnids, crustaceans, and others...
s (for instance the Varroa mite), and the periodically arising mass losses of life in the hives. Since only comparatively few of these colonies were afflicted with microsporidians (evidence showed 14.5% of the cases were afflicted with microsporidian spores, with half of the cases by Nosema apis and/or Nosema ceranae), a correlation between microsporidian affliction and virus infection could not be determined. The question of whether the colonies were dying rather from the "new" version of Nosema, which (possibly) possesses a higher pathogenicity, or due to virus diseases connected with varroa affliction, is internationally controversially continued to be discussed among scientists and beekeepers.
Symptoms
The symptoms of Nosema are relatively nonspecific. This makes it easy to confuse with other diseases of the honeybeeDiseases of the honeybee
- Varroa mites :Varroa destructor and Varroa jacobsoni are parasitic mites that feed off the bodily fluids of adult, pupal and larval bees.Varroa mites can be seen with the naked eye as a small red or brown spot on the bee's thorax....
. It arises mostly in the spring after periods of bad weather, although it may also be a winter disease that is only noticed in the spring when beekeepers first inspect their hives. The female worker bees are most strongly afflicted, less so the drones. The queen bee is rarely infected since afflicted bees rarely participate in feeding the queen. The most notable symptom is dysentery
Dysentery
Dysentery is an inflammatory disorder of the intestine, especially of the colon, that results in severe diarrhea containing mucus and/or blood in the faeces with fever and abdominal pain. If left untreated, dysentery can be fatal.There are differences between dysentery and normal bloody diarrhoea...
. This appears as yellow stripes on the outside of the hive and in severe cases, inside the hive. Bees may be unable to fly ("crawling") due to disjointed wings.
Further symptoms include increased girth of the abdomen, missing sting reflex, and early supersedure of the queen. If the queen is infected, her ovaries degenerate and ovum production drops due to atrophy of the ova, after which she is likely to be superseded. The disease pattern described by Higes et al.. in Spain for Nosema ceranae is slightly different than with Nosema apis. The changes in the digestive system were substantially more serious than with Nosema apis, related to particularly heavy and spacious cell lesions. On the other hand, classical symptoms were missing from Nosema ceranae, such as diarrhea, crawling, large numbers of dead bees in the apiary etc. Bees tend to die away from the apiary, which causes a reduction in food gathered and can eventually lead to colony collapse. Ritter (CVUA Freiburg) reports symptoms can arise throughout the year from Nosema ceranae, in contrast to Nosema apis. In the winter some colonies died within a short time and the bees lay dead in the box (in Spain, hives usually remained empty). Whether these features are related to the new form of Nosema cannot be conclusively proven.
Transmission
Newly emerged bees are always free from infection. Spores must be swallowed by a bee for the infection to be initiated. Spores germinate quickly after entering the ventriculusVentriculus
Ventriculus can refer to:* Ventricle * the midgut in insects* the gizzard in birds...
, and the epithelial cells of the ventriculus are infected when the vegetative stage is introduced by way of the hollow polar filament
Polar filament
A polar filament is a structure found in the polar capsule of myxosporean organisms, and is analogous to the "penetrant" structure found in cnidocytes....
. Once inside a cell, the vegetative stage increases in size and multiplies, effecting an apparent concurrent reduction of RNA synthesis in the host cell. In 6–10 days the infected host epithelial cell becomes filled with new spores. Epithelial cells are normally shed into the ventriculus where they burst – releasing digestive enzyme
Digestive enzyme
'Digestive enzymes' are enzymes that break down polymeric macromolecules into their smaller building blocks, in order to facilitate their absorption by the body. Digestive enzymes are found in the digestive tract of animals where they aid in the digestion of food as well as inside the cells,...
s. When infected cells are shed similarly, they release 30–50 million infective spores when they burst.
Effects on the hive
Nosema spores are spread to other colony members through fecal matter. The disease impairs the digestion of pollen, thereby shortening the life of the bee. A greater proportion of worker bees become infected than drones or queens, probably due to the comb cleaning activities of young bees in which drones and queens do not participate. Nosema infected bees do not attend or feed the queen to the same extent as healthy bees, which helps the queen to escape infection. When the queen becomes infected her ovaries degenerate and her egg laying capacity is reduced due to atrophyAtrophy
Atrophy is the partial or complete wasting away of a part of the body. Causes of atrophy include mutations , poor nourishment, poor circulation, loss of hormonal support, loss of nerve supply to the target organ, disuse or lack of exercise or disease intrinsic to the tissue itself...
of the oocyte
Oocyte
An oocyte, ovocyte, or rarely ocyte, is a female gametocyte or germ cell involved in reproduction. In other words, it is an immature ovum, or egg cell. An oocyte is produced in the ovary during female gametogenesis. The female germ cells produce a primordial germ cell which undergoes a mitotic...
s. Queens that become infected by the parasite during the brood rearing season are superseded by the bees.
The seasonal trend of typical infections exhibits low levels during summer, a small peak in autumn, and a slow rise of infection during winter. It is more common during times of confinement like winter and spring. In the spring the level of infection increases rapidly as brood rearing starts and while flight possibilities are still limited. Colonies in northern climates are more seriously affected than colonies in the south because of the increased amount of time bees are confined in the hive. Nosema, if left untreated, can cause queen supersedure, winter kills, reduced honey yields, and dwindling populations.
Diagnosis
Diagnosis is dependent on microscopic examination of the ventricular (midgut) content and/or fecal matterFeces
Feces, faeces, or fæces is a waste product from an animal's digestive tract expelled through the anus or cloaca during defecation.-Etymology:...
or on PCR analysis of infected tissue. No specific outward sign of disease may be present, although in dissection
Dissection
Dissection is usually the process of disassembling and observing something to determine its internal structure and as an aid to discerning the functions and relationships of its components....
s the ventriculus
Ventriculus
Ventriculus can refer to:* Ventricle * the midgut in insects* the gizzard in birds...
often appears whitish and swollen in late stages of infection. The disease is easily detected in samples of whole bees macerated in water. The fluid is examined under a light microscope at 250–500 x magnification where the characteristic Nosema spores can be observed. Though the spores of N. apis and N. ceranae have slight morphological and ultrastructural differences, they cannot be reliably differentiated via light microscopy. PCR analysis or electron microscopy of spores are the only reliable ways to differentiate between the two types of Nosema infection, given genetic variation and variation in the number of sporular polar filament
Polar filament
A polar filament is a structure found in the polar capsule of myxosporean organisms, and is analogous to the "penetrant" structure found in cnidocytes....
coils between the two species.
Treatment
Treatment with the antibiotic Fumidil B (prepared from Aspergillus fumigatusAspergillus fumigatus
Aspergillus fumigatus is a fungus of the genus Aspergillus, and is one of the most common Aspergillus species to cause disease in individuals with an immunodeficiency....
, the causative agent of Stone Brood) inhibits the spores reproducing in the ventriculus, but does not kill the spores. A disinfection of the honeycombs and utensils is recommended for an extensive disease outbreak.
The spores are sensitive to chemicals such as acetic acid
Acetic acid
Acetic acid is an organic compound with the chemical formula CH3CO2H . It is a colourless liquid that when undiluted is also called glacial acetic acid. Acetic acid is the main component of vinegar , and has a distinctive sour taste and pungent smell...
and Formalin, and physical radiation: ultrasonic
Ultrasound
Ultrasound is cyclic sound pressure with a frequency greater than the upper limit of human hearing. Ultrasound is thus not separated from "normal" sound based on differences in physical properties, only the fact that humans cannot hear it. Although this limit varies from person to person, it is...
and gamma radiation. A natural treatment product called Protofil, made of plant extractions, vitamins, and microelements, was presented at the International Federation of Beekeepers' Association – Apimondia 2004 as a preventative remedy. Other possible natural treatments include HoneyBHealthy, ApiHerb, Vita Feed Gold, Vitafeed Green, Nozevit, and possibly thymol.
Heat treatment in 49 °C (120.2 °F) for 24 hours can be used to kill the spores on contaminated equipment.
Nosema in other animals
Members of the genus Nosema also afflict other species of insects. For example: Nosema vespula (European wasps), Nosema oulemae (cereal leaf beetleCereal leaf beetle
The cereal leaf beetle is a coleopter, belonging to the family of Chrysomelidae, and an agricultural pest and biological control success story. The beetle is mostly blue-black in color, with an area of deep red just behind the head...
), Nosema trichoplusiae (moth Trichoplusia ni), Nosema furnacalis (Ostrinia furnacalis), Nosema necatrix (cutworm moth Mythimna unipuncta
Mythimna unipuncta
The White-Speck is a moth of the family Noctuidae. It is found nearly world-wide, except the east-Palearctic and the Eastern and Australian regions.The wingspan is 41-48 mm. The length of the forewings varies from 18 to 21 mm....
), Nosema locustae (grasshoppers
Grasshoppers
Grasshoppers are insects of the suborder Caelifera.Grasshoppers may also refer to:* Grasshopper , a Hong Kong-based musical group* Grasshopper Club Zürich, a Swiss football club...
) and Nosema pyrrhocoridis (Firebug
Firebug
The firebug, Pyrrhocoris apterus, is a common insect of the family Pyrrhocoridae. Easily recognizable due to its striking red and black colouration, it is distributed throughout the Palaearctic from the Atlantic coast of Europe to northwest China. It has also been reported from the USA, Central...
).
The mark craze (Pébrine disease), caused by Nosema bombycis is one of the most important parasitic diseases of the silk moth.
Other pathogens similar to Nosema cause diseases in mammals. In veterinary practice the term "Nosema" is sometimes used to refer to Encephalitozoonosis
Encephalitis
Encephalitis is an acute inflammation of the brain. Encephalitis with meningitis is known as meningoencephalitis. Symptoms include headache, fever, confusion, drowsiness, and fatigue...
, a disease common in rabbits, in which the brain is infected with the intracellular parasitic microsporidian Encephalitozoon cuniculi
Encephalitozoon cuniculi
Encephalitozoon cuniculi is a eukaryotic organism belonging to the phylum Microsporidia, in the kingdom Fungi. An obligate intracellular parasite, E. cuniculi occurs in laboratory mice and rabbits, monkeys, dogs, rats, birds, guinea pigs, and other mammals including humans. At various early times...
. The term arises from the fact that encephalitozoon were formerly classified as members of the genus Nosema.