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Ebola: The terror

The name itself spells terror.The virus is one of two members of a family of RNA viruses called the Filoviridae. It is string shaped with a little hook or loop at one end which has been named after a river in the Democratic Republic of Congo. The first strain appeared in the Democrtic Reublic of Congo in 1976 and four subtypes are known till date namely Ebola Zaire, Ebola Sudan, Ebola Reston and Ebola Tai( Ebola Ivory Coast).According to a WHO report ,320 cases have been reported till date in Uganda in the Gulu district with 102 cases of death . The exact origin, locations, and natural habitat (known as the "natural reservoir") of Ebola virus remain unknown. However, on the basis of available evidence and the nature of similar viruses, researchers believe that the virus is zoonotic (animal-borne) and is normally maintained in an animal host that is native to the African continent.Contamination is usually through blood or other body fluids from the infected .Liver cells are infected first together with those of the reticuloendothelial system and capillaries are eventually attacked. The capillaries start to leak fluids and plasma proteins. Some patients experience intravascular coagulation, and subsequent loss of normal clotting capability. This eventually leads to shock because of low water volume in the body. This also causes a general interruption of tissue oxygenation causing critical organ failure. Clinical shock, once present, is usually impossible to reverse.

Diagnosing Ebola haemolytic fever in an individual who has been infected only a few days is difficult because early symptoms, such as red and itchy eyes and a skin rash, are nonspecific to the virus and are seen in other patients with diseases that occur much more frequently. If a person has the constellation of symptoms described in the table above, and infection with Ebola virus is suspected, several laboratory tests should be done promptly. These include a blood film examination for malaria and a blood culture. If the suspected patient has bloody diarrhea, a stool culture should also be performed.

Antigen-capture enzyme-linked immunosorbent assay (ELISA) testing, IgG ELISA, polymerase chain reaction (PCR), and virus isolation can be used to diagnose a case of Ebola HF within a few days of the onset of symptoms. Persons tested later in the course of the disease or after recovery can be tested for IgM and IgG antibodies; the disease can also be diagnosed retrospectively in deceased patients by using immunohistochemistry testing, virus isolation, or PCR.

Beware : There has been a reported case of accidental infection in Great Britain where a laboratory technologist became infected after accidentally hurting himself with an infected needle.

Article compiled by H. Ramuth

Brief notes on HLA : Human Leucocytes Antigen

The Human Leucocyte Antigens are essential actors in the immune response. These are molecules which are particular to each and every individual and which are normally found at the surface of our cells. Apart from identical twins, there is only a very slander chance for two human beings to possess identical HLA systems.It is usually this diversity in the HLA system which is responsible for the rejections obtained in transplantations .Indeed if one introduces in his organism cells possessing HLA different from those of the body, these are immediately recognised and destroyed by killer cells ( T Lymphocytes ) of the immune system. Grafted tissues suffer necrosis and the implant is rejected.

How do HLA molecules function in a normal immune response ?

If one cell of the organism is infected by a virus for example, the cell will transpose some of the virus fragments ( or remains ) at its surface. There will therefore be viral fragments as well as HLA at the surface of the cell. These two molecules will be recognised by the killer T lymphocytes and treated as foreigh to the body and will subsequently be destroyed. The HLA ( more precisely the HLA-A and HLA-B ) is therefore essential in the immune response against viral infection.

Moreover, lymphocytes responsible for the whole immune system response will recognise pathogens ( eg bacteria ) only when the latter’s fragments are presented to them at the surface of specialised cells ( macrophages mostly ) in association with HLA molecules ( HLA-DR ) . Hence , the HLA system which permits self recognition plays a key role in the body against infections.

Article compiled by H.Ramuth