Changes

The nucleocapsid protein is used as the antigen of choice in serological assays. Blood samples can be used to detect the virus during the early phase using virus propagation, antigen detection and RT-PCR.  

The nucleocapsid protein is used as the antigen of choice in serological assays. Blood samples can be used to detect the virus during the early phase using virus propagation, antigen detection and RT-PCR.  

<br><br>

<br><br>

During the acute stages ELISA or EIA can be used to confirm the presence of IgM antibody to the virus, which allows recent infections to be diagnosed. ELISA’s based on recombinant RVF virus proteins have been developed which negates the need for biosecure facilities and are used in a number of species.<ref name="vaccine"/>.Cross reactions may occur with other ''phleboviruses''<ref name="vaccine"/>  

During the acute stages '''[[ELISA]]''' or '''EIA''' can be used to confirm the presence of IgM antibody to the virus, which allows recent infections to be diagnosed. ELISA’s based on recombinant RVF virus proteins have been developed which negates the need for biosecure facilities and are used in a number of species.<ref name="vaccine"/>.Cross reactions may occur with other ''phleboviruses''<ref name="vaccine"/>  

<br><br>

<br><br>

RT-PCR is the standard method used in most laboratories as it has a high sensitivity. This is useful for rapid diagnosis and can also be used to detect RVF virus in mosquito pools.<ref name="oie" />

'''RT-[[PCR]]''' is the standard method used in most laboratories as it has a high sensitivity. This is useful for rapid diagnosis and can also be used to detect RVF virus in mosquito pools.<ref name="oie" />

<br><br>

<br><br>

Virus neutralisation tests (VNT) are very specific and sensitive and can be performed in a biosecure laboratory. They are also the prescribed test for international trade, though it cannot differentiate between vaccinated and infected animals.<ref name="oie" /> It is the only method to detect functional antibodies though a low level of cross reaction to some other ''phleboviruses'' has been observed.<ref name="vaccine"/> Plaque reduction neutralisation assays are the most commonly used VNTs and involve incubating the virus and heat inactivated serum allowing the virus to infect. 4-6 days later the presence of cytopathic plaques is observed.

'''Virus neutralisation tests '''(VNT) are very specific and sensitive and can be performed in a biosecure laboratory. They are also the prescribed test for international trade, though it cannot differentiate between vaccinated and infected animals.<ref name="oie" /> It is the only method to detect functional antibodies though a low level of cross reaction to some other ''phleboviruses'' has been observed.<ref name="vaccine"/> Plaque reduction neutralisation assays are the most commonly used VNTs and involve incubating the virus and heat inactivated serum allowing the virus to infect. Four to six days later the presence of cytopathic plaques is observed.

<br><br>  

<br><br>  

Haemagglutination inhibition (HI) and complement fixation assays are available but show extensive cross reactivity with other ''phlebovirus'' species.<ref name="vaccine"/>  HI assays are used in non endemic areas but animals previously infected with other ''phleboviruses'' may show a positive result.<ref name="oie" /> Immunofluorescence can also be used.

'''[[Agglutination|Haemagglutination inhibition]]''' (HI) and complement fixation assays are available but show extensive cross reactivity with other ''phlebovirus'' species.<ref name="vaccine"/>  HI assays are used in non endemic areas but animals previously infected with other ''phleboviruses'' may show a positive result.<ref name="oie" /> '''[[Immunofluorescence]]''' can also be used.

<br><br>

<br><br>

Definitive confirmation can be carried out by virus isolation, however due to the zoonotic risk this can only be carried out in biosecure facilities.<ref name="oie" />

Definitive confirmation can be carried out by '''virus isolation''', however due to the zoonotic risk this can only be carried out in biosecure facilities.<ref name="oie" />

<br><br>

<br><br>

Histopathology on tissue samples will show cytopathology and immunostaining can be used to identify RVF antigen in cells. On post mortem during the viraemic stage, widespread petechiae and ecchymoses on serous surfaces and organs will be seen and  present in the body cavities. In older animals, the liver is enlarged and inflamed, with many foci of necrosis which are bronzed and jaundiced. The gall bladder may also be distended and haemorrhagic. Lymph nodes are enlarged and their germinal centres may be necrotic on closer examination. Extensive subcapsular haemorrhage in the spleen is usual. Renal changes include oedema and congestion. Epicardial and endocardial haemorrhages are often present on the heart.<ref>[http://www.fao.org/docrep/006/Y4611E/y4611e05.htm FAO Signs of Rift Valley Fever] accessed June 23, 2013</ref>

'''Histopathology''' on tissue samples will show cytopathology and immunostaining can be used to identify RVF antigen in cells. On post mortem during the viraemic stage, widespread petechiae and ecchymoses on serous surfaces and organs will be seen and  present in the body cavities. In older animals, the liver is enlarged and inflamed, with many foci of necrosis which are bronzed and jaundiced. The gall bladder may also be distended and haemorrhagic. Lymph nodes are enlarged and their germinal centres may be necrotic on closer examination. Extensive subcapsular haemorrhage in the spleen is usual. Renal changes include oedema and congestion. Epicardial and endocardial haemorrhages are often present on the heart.<ref>[http://www.fao.org/docrep/006/Y4611E/y4611e05.htm FAO Signs of Rift Valley Fever] accessed June 23, 2013</ref>

==Treatment==

==Treatment==