Pussjuka / kyssjuka /Kissing Disease / Epstein-barr virus / EBV
GiantMicrobes är mjukdjur som ser ut som små, små mikrober - bara det att de är förstorade sådär en miljon gånger. De ger bokstavligen ett ansikte åt förkylningen, fotsvampen, hostan, den dåliga andedräkten eller vägglusen. Varje GIGANTmicrobe är mellan ca 38-50 cm. Med följer ett foto på hur den riktiga mikroben ser ut samt en kort information på engelska.
Ursprungligen skapade i USA att användas i undervisningssyfte, har GIANTmicrobes nu blivit storsäljare i museishoppar, apotek, bokhandlar och designbutiker världen över.
GIANTmicrobes är ett roligt verktyg i undervisningen om hälsa och sjukdomar, men även en uppskattad gåva som passar alla åldrar. Definitivt roligare än ett krya-på-dig kort till en sjuk vän.
Pussjuka / kyssjuka /Kissing Disease / Epstein-barr virus / EBV
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Körtelfeber, infektiös mononukleos, mononukleos eller kyssjuka, är en infektionssjukdom vars främsta symptom är halsont, hög feber och svullna lymfkörtlar i hals, armhålor och ljumskar. Sjukdomen orsakas av Epstein-Barrvirus (EBV), även kallat humant herpesvirus 4, som sprids mellan människor genom direktkontakt, främst via saliv. Sjukdomen är spridd över hela världen och de flesta människor utsätts för det orsakande viruset någon gång men sjukdomen utvecklas främst hos ungdomar i åldern 10–25 år. Mindre barn som smittas med viruset får ofta inga sjukdomssymtom. Sjukdomen är oftast ofarlig och infektionen brukar läka ut själv. Inkubationstiden är 4–6 veckor. Sjukdomen brukar vara i två till tre veckor, ibland upp mot en månad. Trötthet en längre tid efteråt är vanligt, ibland i flera månader.
Det finns inget vaccin mot sjukdomen. Efter infektion utvecklas en immunitet som gör att man är skyddad mot ytterligare insjuknande. Dock finns information som tyder på att det orsakande viruset som är ett herpesvirus kan finns kvar latent i kroppen och att sjukdomen åter kan bryta ut om personen fått nedsatt immunförsvar.
Körtelfeber orsakas av Epstein-Barrvirus vilket smittar genom framförallt saliv. På grund av dess tendens att smitta via saliv och att det är känt att kyssar är ett av de sätt som viruset kan spridas på, kallas sjukdomen på engelska bland annatkissing disease. Viruset kan även smitta via kontaktsmitta vid otillräcklig handhygien.
Körtelfeber orsakas av ett virus och är därför inte möjlig att behandla med antibiotika. Istället brukar symptomen behandlas till exempel med hjälp av febernedsättande medel för att underlätta sjukdomstiden. Receptfria febernedsättande medel finns att tillgå och det rekommenderas att dricka mer än vanligt när man har feber. Antiinflammatoriska läkemedel har också en visad effekt mot halsont med körtelfeber och det finns receptfria och receptbelagda läkemedel av denna typ som kan lindra besvären i halsen och medföra enklare förtäring av både mat och dryck. Sjukvården bör alltid uppsökas för rådgivning och behandling om man mår dåligt och har feber som inte går ner, svårigheter att svälja eller om man fått diagnosen körtelfeber och får ont i magen.
Latent EBV in B cells can be reactivated to switch to lytic replication. This is known to happen in vivo, but what triggers it is not known precisely. In vitro, latent EBV in B cells can be reactivated by stimulating the B cell receptor, so reactivation in vivo probably takes place when latently infected B cells respond to unrelated infections. In vitro, latent EBV in B cells can also be reactivated by treating the cells with sodium butyrate or TPA.
Transformation of B-lymphocytes
When EBV infects B cells in vitro, lymphoblastoid cell lines eventually emerge that are capable of indefinite growth. The growth transformation of these cell lines is the consequence of viral protein expression.
EBNA-2, EBNA-3C and LMP-1 are essential for transformation, while EBNA-LP and the EBERs are not.
It is postulated that following natural infection with EBV, the virus executes some or all of its repertoire of gene expression programs to establish a persistent infection. Given the initial absence of host immunity, the lytic cycle produces large amounts of virus to infect other (presumably) B-lymphocytes within the host.
The latent programs reprogram and subvert infected B-lymphocytes to proliferate and bring infected cells to the sites at which the virus presumably persists. Eventually, when host immunity develops, the virus persists by turning off most (or possibly all) of its genes, only occasionally reactivating to produce fresh virions. A balance is eventually struck between occasional viral reactivation and host immune surveillance removing cells that activate viral gene expression.
The site of persistence of EBV may be bone marrow. EBV-positive patients who have had their own bone marrow replaced with bone marrow from an EBV-negative donor are found to be EBV-negative after transplantation.
The Epstein–Barr virus is named after Michael Anthony Epstein, a professor emeritus at the University of Bristol, and Yvonne Barr (born 1932 in London), a 1966 Ph.D graduate from the University of London, who together discovered and documented the virus. In 1961, Epstein, a pathologist and expert electron microscopist, attended a lecture on "The Commonest Children's Cancer in Tropical Africa—A Hitherto Unrecognised Syndrome." This lecture, by Denis Parsons Burkitt, a surgeon practicing in Uganda, was the description of the "endemic variant" (pediatric form) of the disease that bears his name. In 1963, a specimen was sent from Uganda to Middlesex Hospital to be cultured. Virus particles were identified in the cultured cells, and the results were published in The Lancet in 1964 by Epstein, Bert Achong, and Barr. Cell lines were sent to Werner and Gertrude Henle at the Children's Hospital of Philadelphia who developed serological markers. In 1967, a technician in their laboratory developed mononucleosis and they were able to compare a stored serum sample, showing that antibodies to the virus developed. In 1968, they discovered that EBV can directly immortalize B cells after infection, mimicking some forms of EBV-related infections, and confirmed the link between the virus and infectious mononucleosis.
A relatively complex virus, EBV is not yet fully understood. Laboratories around the world continue to study the virus and develop new ways to treat the diseases it causes. One popular way of studying EBV in vitro is to use bacterial artificial chromosomes. Epstein–Barr virus and its sister virus KSHV can be maintained and manipulated in the laboratory in continual latency. While many viruses are assumed to have this property during infection of their natural host, they do not have an easily managed system for studying this part of the viral lifecycle. Genomic studies of EBV have been able to explore lytic reactivation and regulation of the latent viral episome.
Epstein–Barr virus infection
|Classification and external resources|
Epstein–Barr can cause infectious mononucleosis, also known as 'glandular fever', 'Mono' and 'Pfeiffer's disease'. Infectious mononucleosis is caused when a person is first exposed to the virus during or after adolescence. Though once deemed "The Kissing Disease," recent research has shown that transmission of Mono not only occurs from exchanging saliva, but also from contact with the airborne virus. It is predominantly found in the developing world, and most children in the developing world are found to have already been infected by around 18 months of age. Infection of children can occur when adults mouth feed or pre-chew food before giving it to the child. EBV antibody tests turn up almost universally positive. In the United States roughly half of five-year-olds have been infected,.
The strongest evidence linking EBV and cancer formation is found in Burkitt's lymphoma and nasopharyngeal carcinoma. Additionally, it has been postulated to be a trigger for a subset of chronic fatigue syndrome patients as well as multiple sclerosis and other autoimmune diseases.
Burkitt's lymphoma is a type of Non-Hodgkin's lymphoma and is most common in equatorial Africa and is co-existent with the presence of malaria. Malaria infection causes reduced immune surveillance of B cells immortalized by EBV, resulting in an excessive number of B cells and an increased likelihood of an unchecked mutation. Repeated mutations can lead to loss of cell-cycle control, causing excessive proliferation observed as Burkitt's lymphoma. Burkitt's lymphoma commonly affects the jaw bone, forming a huge tumor mass. It responds quickly to chemotherapy treatment, namely cyclophosphamide, but recurrence is common.
Other B cell lymphomas arise in immunocompromised patients such as those with AIDS or who have undergone organ transplantation with associated immunosuppression (Post-Transplant Lymphoproliferative Disorder (PTLPD)). Smooth muscle tumors are also associated with the virus in malignant patients.
Nasopharyngeal carcinoma is a cancer found in the upper respiratory tract, most commonly in the nasopharynx, and is linked to the EBV virus. It is found predominantly in Southern China and Africa, due to both genetic and environmental factors. It is much more common in people of Chinese ancestry (genetic), but is also linked to the Chinese diet of a high amount of smoked fish, which contain nitrosamines, well known carcinogens (environmental).
Symptoms of infectious mononucleosis are fever, sore throat, and swollen lymph glands. Sometimes, a swollen spleen or liver involvement may develop. Heart problems or involvement of the central nervous system occurs only rarely, and infectious mononucleosis is almost never fatal. There are no known associations between active EBV infection and problems during pregnancy, such as miscarriages or birth defects. Although the symptoms of infectious mononucleosis usually resolve in 1 or 2 months, EBV remains dormant or latent in a few cells in the throat and blood for the rest of the person's life. Periodically, the virus can reactivate and is commonly found in the saliva of infected persons. Reactivated and post-latent virus may pass the placental barrier in (also seropositive) pregnant women via macrophages and therefore can infect the fetus. Also re-infection of prior seropositive individuals may occur. In contrast, reactivation in adults usually occurs without symptoms of illness.
EBV also establishes a lifelong dormant infection in some cells of the body's immune system. A late event in a very few carriers of this virus is the emergence of Burkitt's lymphoma and nasopharyngeal carcinoma, two rare cancers. EBV appears to play an important role in these malignancies, but is probably not the sole cause of disease.
Most individuals exposed to people with infectious mononucleosis have previously been infected with EBV and are not at risk for infectious mononucleosis. In addition, transmission of EBV requires intimate contact with the saliva (found in the mouth) of an infected person. Transmission of this virus through the air or blood does not normally occur. The incubation period, or the time from infection to appearance of symptoms, ranges from 4 to 6 weeks. Persons with infectious mononucleosis may be able to spread the infection to others for a period of weeks. However, no special precautions or isolation procedures are recommended, since the virus is also found frequently in the saliva of healthy people. In fact, many healthy people can carry and spread the virus intermittently for life. These people are usually the primary reservoir for person-to-person transmission. For this reason, transmission of the virus is almost impossible to prevent.
The clinical diagnosis of infectious mononucleosis is suggested on the basis of the symptoms of fever, sore throat, swollen lymph glands, and the age of the patient. Usually, laboratory tests are needed for confirmation. Serologic results for persons with infectious mononucleosis include an elevated white blood cell count, an increased percentage of certain atypical white blood cells, and a positive reaction to a "mono spot" test.
There is no specific treatment for infectious mononucleosis, other than treating the symptoms. No antiviral drugs or vaccines are available. Some physicians have prescribed a 5-day course of steroids to control the swelling of the throat and tonsils. The use of steroids has also been reported to decrease the overall length and severity of illness, but these reports have not been published.
It is important to note that symptoms related to infectious mononucleosis caused by EBV infection seldom last for more than 4 months. When such an illness lasts more than 6 months, it is frequently called chronic EBV infection. However, valid laboratory evidence for continued active EBV infection is seldom found in these patients. The illness should be investigated further to determine if it meets the criteria for chronic fatigue syndrome, or CFS. This process includes ruling out other causes of chronic illness or fatigue.