Enzootic leukosis in cattle
The enzootic bovine leukosis , and bovine leukemia or Bovine leukemia , is a for cattle , buffalo and water buffalo occurring leukemia .
etiology
It occurs in several forms: a sporadic without viral etiology, the cause of which is unknown and an infectious, the cause of the bovine leukemia virus (BLV, bovine leukemia virus is). The virus belongs to the Retroviridae family , genus HTLV-BLV group, and thus to the ss-RNA viruses. This form of leukemia is a B-cell leukemia or a malignant lymphoma from B cells .
Leukosis is the result of a disease similar to mononucleosis , which usually regresses. It could be caused by a superantigen because the cells have no specificity for an antigen . Only in a few animals does the disease develop into leukemia.
Leukosis occurs naturally only in cattle, buffalo and water buffalo, but can also be transmitted to sheep. The bovine leukemia virus can also be transmitted experimentally to numerous other animal species, and human cells can also be infected.
Clinical symptoms and course
Most of the time, the infected animals show hardly any clinical signs. The maximum incidence of the tumor type is between 5 and 8 years. The onset of symptoms can include decreased milk yield, difficulty swallowing, paralysis, cardiopathies and exophthalmos. This is followed by enlarged lymph nodes with a greasy cut surface. The spleen is also often enlarged.
A distinction is made between the following forms:
- Seroconversion : Despite persistent infection, the animals show no changes in the blood count and no clinical symptoms; this is also referred to as the "aleukemic form".
- Persistent lymphocytosis : Antibodies are formed in 30% of all animals. However, they show no clinical symptoms.
- Tumor development : After about 4–8 years, tumors develop in up to 10% of the animals.
Combat
Because of the economic damage will be tried in Europe, the BLV eradicate. In Germany, enzootic bovine leukosis is one of the notifiable animal diseases. The control takes place according to the regulation for the protection against the leukosis of the cattle (cattle leukosis regulation) . Herd in which reagents have been detected by means of a serological examination are subjected to a partial remediation or harvesting in order to prevent further spread. Vaccination is prohibited in Germany. However, Germany is considered to be bovine leukosis-free. Most infected cattle will not develop leukemia . Therefore, in other states z. B. in the USA and Canada waived an extermination.
literature
- Michael Rolle, Anton Mayr (ed.): Medical microbiology, infection and epidemic theory . 8th revised edition. Enke Verlag, Stuttgart 2006, ISBN 3830410603 .
