Editing Nosema apis (section)

== Pathology ==
[[File:Temporal-Analysis-of-the-Honey-Bee-Microbiome-Reveals-Four-Novel-Viruses-and-Seasonal-Prevalence-of-pone.0020656.s006.ogv|thumb]]
''Nosema apis'' is a single-celled parasite of the [[western honey bee]] (''Apis mellifera'').  The species is of the class [[Microsporidia]], which were previously thought to be [[protozoan]]s, but are now classified as fungi or fungi-related.<ref>{{cite journal |doi=10.1186/1471-2148-6-74 |pmid=17010206 |pmc=1599754 |year=2006 |last1=Liu |first1=Yajuan J. |title=Loss of the flagellum happened only once in the fungal lineage: Phylogenetic structure of kingdom Fungi inferred from RNA polymerase II subunit genes |journal=BMC Evolutionary Biology |volume=6 |pages=74 |last2=Hodson |first2=Matthew C. |last3=Hall |first3=Benjamin D. |doi-access=free }}</ref> Microsporidia are [[intracellular parasites]] and they infect the epithelial cells of the midgut.<ref>{{cite journal |doi=10.1016/j.jip.2009.06.017 |pmid=19909977 |title=Nosema ceranae in European honey bees (Apis mellifera) |journal=Journal of Invertebrate Pathology |volume=103 |pages=S73–S79 |year=2010 |last1=Fries |first1=Ingemar |bibcode=2010JInvP.103S..73F |s2cid=30393641 }}</ref> ''N. apis'' has a resistant spore that withstands temperature extremes and dehydration. In 1996, a similar microsporidian parasite of the [[Apis cerana|eastern honey bee]] (''Apis cerana'') was discovered in Asia, which was named ''[[Nosema ceranae]]''. Little is 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.<ref>{{cite journal |doi=10.1111/j.1550-7408.2008.00374.x |pmid=19457054 |pmc=2779023 |title=Morphological, Molecular, and Phylogenetic Characterization of ''Nosema'' ceranae, a Microsporidian Parasite Isolated from the European Honey Bee,Apis mellifera |journal=Journal of Eukaryotic Microbiology |volume=56 |issue=2 |pages=142–147 |year=2009 |last1=Chen |first1=Yanping P. |last2=Evans |first2=JAY D. |last3=Murphy |first3=Charles |last4=Gutell |first4=Robin |last5=Zuker |first5=Michael |last6=Gundensen-Rindal |first6=Dawn |last7=Pettis |first7=Jeff S. }}</ref> <!-- Spanish bee researchers (Higes et al.) reported that --> The new pathogen was discovered in 2005 in [[Spain]]<ref>Higes et al.</ref> and was observed to have a notably higher virulence than the western version. The disease caused by ''N. 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. Within a few years, a strongly increased propagation of ''Nosema'' was observed, and its occurrence was happening all year round due to the higher resistance of ''N. 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 ''N. ceranae'' in Spain, which has now replaced ''N. 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 conjectured a similar cause of increased bee colony losses reported in other European countries, such as those experienced in France since end of the 1990s and in Germany in 2002 and 2003.

In the samples examined in German laboratories in the winter of 2005/2006, the new pathogen was present in eight of 10 examined bee hives (CVUA Freiburg), with the distribution varying from state to state. The bees with the classical pathogen ''N. apis'' came from [[Thuringia]] and [[Bavaria]], whereas ''N. ceranae'' prevailed in [[Baden-Wuerttemberg]], Bavaria, and [[North Rhine-Westphalia]]. Cases were also reported from [[Switzerland]] (July 2006) and from several regions of [[Italy]] (September 2006) where ''N. ceranae'' was found in bee colonies with increased mortality.

German scientists<ref name=Ritter>Ritter, Wolfgang, (CVUA Freiburg): [http://www.imkerschule-sh.de/index.php?jahr%5B%5D=2006&imk_themen=j&n=28 Nosema ceranae. Asiatischer Nosema-Erreger festgestellt. Neu verbreitet oder erst jetzt entdeckt] (translation: Asian nosema pathogene diagnosed. Newly distributed or only lately discovered)?] ADIZ, die Biene, der Imkerfreund (Zeitschrift der Landesverbände) 3/2006, S. 7 (Online auf der Website des Landesverbandes Schleswig-Holsteinischer und Hamburger Imker e. V.).</ref> do not know whether ''N. ceranae'' was already present in Europe and simply had not yet been differentiated from ''N. apis''. The current disease processes possibly 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. However, signs indicate the disease process of ''Nosema'' has changed, and the disease arises now all year round.

The investigation of 131 bee colonies from Bavaria<!-- within the framework of a dissertation --><ref>Zohni, Dalia: ''[http://edoc.ub.uni-muenchen.de/archive/00005873/01/Zohni_Dalia.pdf Zur Epidemiologie arthropodenübertragener Virosen der Honigbiene, Apis mellifera, in Bayern] (translation: About epidemiology arthropode-transmissioned viral diseases of the honey bee, Apis mellifera in Bavaria). [[München]], Germany 2006 (Inaugural-Dissertation at the Tierärztlichen Fakultät of the [[Ludwig Maximilian University of Munich]]).</ref> 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 ''N. apis'' and/or ''N. ceranae''), a correlation between microsporidian affliction and [[latent viral infection|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 controversially continuing to be discussed internationally among scientists and beekeepers.